Home

Technical, Practical and Manufacturing Feasibility of Technologies

1. Range of Fire Incident Coverage Based on existing fire data All cooktop fire over 90 will be addressed by this fire containment system since it actuates after the detection of fire Percent of new product sales covered by this technology Less then 90 since island cooktop installation and under cabinet installation probably not be possible with the drop hood The degree of mitigation of fires addressed It extinguishes fire once it has commenced Effect of Safety System on Cooktop Performance After Actuation of System Will require significant cleaning and adjustment after actuation since fire have started already and the hood has been dropped on top of the cooktop Effect of Actuation on the Safety System Needs specialist help for adjustment of drop hood back to its position and resetting the actuation and release mechanism Potential for False Actuation None since temperature sensor has to register a relatively high temperature to actuate Can Operate Over product life w o failure safety factor of 2 Drop hood release mechanism has no data and looks problematic due to the hood is being released using gravity pull Unknown impact force hood might get damaged when it impacted the cooktop surface Can operate within reasonably foreseeable misuse conditions durability Looks problematic but no data Safety system is out of reach of user during cooktop operation but drop hood is released using gravity pull Unknown impact force hood might
2. Description Motion sensor spec area covearge determine if user is present If not depending on 2nd sensor power level heat sensor etc No user detected 1st alarm then some heat source manipulation Motion sensor detect if person is near stove specified area coverage If not will turn off electric heater after a specified pre determined time leave stove is disabled permanently until user manually reset it Add on to old stove None Manual fire extinguisher material powder in bottle User has to squirt the plastic bottle containinjNational Fireproofing Co Company None None Motion sensor determine user presence The 1st time user not detected after pre set period stovqNone disabled temporarily for a pre set period When user enters it is auto enabled The 2nd time user MANUAL FIRE EXTINGUISH AND COOKING FIRE DETERMINATION METHOD Motion sensor determine user presence For the 1st time user not detected after pre set period stove disabled temporarily for a pre set period When user enters it is auto enabled The 2nd time user leave stove is disabled permanently until user manually reset it Integrated Motion detector determined user s presence near stove for a pre set time If no user is around controller sent a signal by which to manipulate off electric heater Can use cooking modes broil manual and the rest is automated Determine cook mode auto when not in broil mode by the time required to inc
3. Fire detected by sensor then gas valve is cut off then liquid fire extinguisher is pressure released Finally alarm is activated to warn user Heat sensor diodes thermistor detect fire activate fire extingusher release and activates audible alarm which activates gas electricity shut off to heat source sensor alarm battery operated 17 JP 7132151 18A US 6044913 None None 21st Century Int l Fire Equipment amp Services Corp 18B The Guardian Ill Fire detection suppression system concealed in hood or in kitchen cabinet above range When fire detected using heat sensors diodes within hood auto shuts off fuel supply to stove gas amp electric while releasing extinguisher Optional audible alarm amp pull stations 19 JP 58050096 IR sensor is used to detect fire above cooktop on wall behind cooktop Then from inside the rangehood fire extinguisher will be released Twenty First Century MATSUSHITA ELECTRIC USE NON OPTICAL TEMP OR FIRE SENSOR 20 JP 58152575 Stove Alarm Flame sensor behind the cooktop at a level just above the cooking vessel activated a spray nozzle that releases fire extinguisher from behind the cooktop onto the pot pan on cooktop and then cut off gas valve Sensor is IR An auxiliary system using an IR temperature sensor mounted above the cooktop on the wall behind it Reacts to heat if T of cookstove gt Tthres it will turn on an alarm and some v
4. Safety System Maintenance User maintenance procedure is the same as conventional cooktop Power level sensor will most likely located away from grease and food build up under the cooktop surface Cookware Applicability All cookware can be used with cooktop at any normal environment Range of Fire Incident Coverage Based on existing fire data Probably will catch less than 40 of cooking fire incident since it only warns user that burner has been on for a certain time If user is far enough from the kitchen not to hear the alarm then the system is useless Percent of new product sales covered by this technology Will work fine with electric cooktop but needs more development work for gas burner power sensor The degree of mitigation of fires addressed Only gives warning of possible cooking fire pre ignition condition Effect of Safety System on Cooktop Performance After Actuation of System None no special clean up was necessary if alarm works as intended it alerts user to check on cooktop and fire did not occur Effect of Actuation on the Safety System User has to reset manually to turn off alarm Potential for False Actuation Potential for false negative depending on the selection of limiting power level Food oil can still get really hot with lower power setting And user might put a pot with an already hot food content Can Operate Over product life w o failure safety factor of 2 Looks good but not data It is just a simple timer and a
5. TECHNOLOGIES ELIM NATED FROM CONSIDERATION FOR VARIOUS REASONS 29 No Technology Description Company Explanation 1 JP 4080525 Fire prevention by the comparing the temperature gradient of the pan with NORITZ CORP Find patent s figure later and pre set conditions If gradient lt preset value A then actual T is compared to realize it is for oven preset Ta if less continue If more stop 2 JP 5018539 An odor sensor is used to determine what kind of food is cooked and also to Sharp Corp Find patent s figure later and 3 JP 8086445 determine if food is over heating It is connected to controller that can manipulate heat source A contact touch sensor combined with Tpan bottom sensor is used to determine if pan pot is on top of burner When pan is not on burner burner flame is either reduced or off so no cloth sleeve catch fire realize it is for oven Tokyo Gas Co Ltd Address only small of cooking fire 4 JP 4093529 5 US 5283412 A photoelectric sensor light projector and receiver is installed in downdraft cooking vent hood When smoke level in the vent is gt pre set value sensor will send signal to turn on alarm and turn off heater A device to measure pan or content temperature during induction heating independent of cooking vessel diameter surface configuration heat conductor w current measurement Matsushita Electric Ind Corp Optical sensor easily soiled by grease amp not accessibl
6. The current sensor approach is not technically feasible due to lack of reliability and durability The Japanese sensor technology is a reasonable starting point for a development effort but it is currently applied only to open burner gas systems a product class that is rapidly decreasing in US market share In addition some type of self check algorithm would need to be developed to implement a fail safe system The benefit of this approach is that it would impose significantly less constraint on consumer behavior than any of the systems that require attended cooking It is potentially less problematic to implement than the fire extinguishing systems However it would take an extensive development effort of 2 3 years to develop the contact temperature sensor and robust cooking algorithms This approach is currently not feasible for glass ceramic smoothtop cooktops In these systems pot temperature need to be inferred from glass temperature or from the temperature in the region below the glass The variations in contact between pots and the glass ceramic surface make the temperature difference between the glass and the pot too variable The thermal inertia of the glass ceramic is a problem as well to have appropriate response time to avoid a potential cooking fire 4 56 References TTT Prepared By Prepared For for Ctrl Sys For Preventing A TC based cooking fire solution developed for gas ranges using 1 off 1 Food Ignition on Gas R
7. 1600 Temperature F D10 1000 800 600 400 200 100ml Oil Test in Stainless Steel Pan on Rinnai Range 200 400 600 800 1000 1200 Time s PC pan contents PBC pan bottom center PBE pan bottom edge 1400 1600 Temperature F D11 1000 800 600 400 200 100ml Oil Test in Aluminum Pan on Rinnai Range 200 400 PC pan contents 600 800 Time s PBC pan bottom center 1000 1200 PBE pan bottom edge 1400 1600 100ml Oil Test in Cast Iron Pan on Rinnai Range 1000 800 600 Temperature F 400 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge D12 Oil Ignition Test on Rinnai Uncontrolled Burner in Stainless Steel Pan 1000 ignition 700s Tee 800 600 Temperature F 400 200 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge D13 Oil Ignition Test on Rinnai Uncontrolled Burner in Aluminum Pan 1000 burner firing rate increased slightly es Vere pret 1 COC ONO aA Sg Nace mon PBE XW 600 Lf s S PC PBG a ae a ignition 400 1380s 200 0 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge D14 Oil Ignition Test on Rinnai Uncontrolled Burne
8. A pan contact temperature sensor monitors the temperature of the pan When the pan bottom temperature exceeds a threshold limit the controller will decrease the heat input unless the motion detector senses the presence of the cook near the cooktop If a person is detected system might give a warning alarm to alert of the cook of a possible near fire condition ALARM PAN 2orteom TEMPERATURE SENSO MOTION l TME TIME INPUT PONER b PFPVED No Momo AND T gt T Peano Figure 4 11 Prevent Unattended Cooking Warning and Control Motion T sensor 4 13 Prevent Unattended Cooking Warning and Control Motion Power Sensor Tech Class 12 This approach to prevent unattended cooking actuates only when the power level of the heat source surpasses a pre set level e g Medium High When the system actuates the motion sensor monitors the presence of a user near the cooktop When no user is detected after a pre set duration the alarm is sounded If there is no response to the alarm e g the user activates a re set button the controller will reduce the heat input to the burner or element ALARM POWER LEVEL SENSop MOTION POWER amp REDUCED FPM HH LENEL IF Ne Mono DETECTED Figure 4 12 Prevent Unattended Cooking Warning and Control Motion Power sensor 4 14 Prevent Unattended Cooking Warning and Control Power Level Se
9. No patent found that specifically address this type of technology on gas cooktop although it does not seem difficult to do Components system availability Most parts are available off the shelf or has been manufactured at high volume at low cost Installation No added effort than installing conventional range Serviceability Some training or new equipment is necessary for servicing the sensor PREVENT UNATTENDED COOKING WARNING AND CONTROL POWER LEVEL SENSOR TIMER Effect on Cooking Process All cooking procedures can be done on the cooktop as long as user maintains cooking operation simmer is possible as long as power level is kept at a minimum Continuous searing might be affected as heat source might continually turns on and off which might affect temperature of cooking vessel Effect on Cooking Time As long as it is attended cooking time will be no different Effect of System on Consumer Behavior While Operating the Cooktop User will need to read manual to learn that constant supervision and user input is necessary to keep cooktop from manipulating heat source automatically Limits availability or efficacy of marketed cooktop features None Ease of System Verification User can easily verify by turning power level on high and wait to see if cooktop will turn on signal and then manipulate the heat source output 14 Safety System Maintenance user maintenance procedure is the same as conventional cooktop Power level sensor
10. Typical units have been in use for 10 15 yeas with no problems The lens is the only exposed part that need to be inspected If grease were to build up on its surface it could reduce the transmittance of the IR source The typical range of PIR sensors can be seen on the figure below TOP VIEW i 3 2 3 0 0 Of 20 30f 40ft SOft 60 ft Bm Bar 96m 2m 46m 8m 10 ft SIDE VIEW 3 2m z 0 0 Of 20 30ft Att SOft BON 2m Bar Sm 42m 16m am The field of view of the passive sensors is not very wide As shown in the diagram it could be possible to be standing a few feet from the range but be out of the view of the sensor Active Sensors Active sensors use microwave ultrasonic or radio frequency energy to detect motion In their simplest form they are miniature radar systems They emit a pulse of energy for a few milliseconds and then spend the next few milliseconds listening for its return This process repeats several hundred times a second When there is a moving target in the field of view FOV of the detector the echo returned to the receiver will differ from the no motion echo A rapid enough change in the echo signifies detected motion The microwave systems use a frequency within the K band 24 05 GHz 24 25 GHz 4 45 Ultrasonic systems use a frequency in the 40 kHz 50 kHz range The radio frequency systems operate at 6 5 Ghz Like IR systems ultrasonic systems also can be affected by
11. and AHAM member companies concluded that behaviors associated with range top cooking must be given special emphasis The statistics compiled by the Fire Analysis and Research Division of the National Fire Protection Agency mirror the results of the NASFM The April 2000 NFPA report entitled US Home Cooking Fire Patterns and Trends stated that 73 of home cooking fires originated from surface cooking Therefore we reviewed fire mitigation or management technologies that are intended to address surface cooking fires independent of the origin of these fires In addition the statistics indicate that a significant number of fires are associated with unattended cooking fires and the ignition of cooking materials Therefore we also reviewed technologies that specifically target unattended cooking and the ignition of cooking materials 1 2 2 Objective The objective of this study is to evaluate the technical practical and manufacturing feasibility of technologies to address surface cooking fires Specifically feasibility is established by evaluating the potential for the technology to be designed in such a way as to 1 be effective in mitigating surface cooking fires and 2 meet industry standards for reliability durability cooking performance safety operability and manufacturability 3 Approach The program involved three major activities collect information conduct evaluation prepare report that were further divided into the
12. Components system availability No additional part needs to be installed or developed Installation No additional part installed Serviceability No additional part installed that might have any effect to current cooktop service routine Appendix G Used Oil Analysis and Testing Most of the oil ignition tests described in the experimental section of this report were carried out with unused oil It is known that during cooking the concentration of free fatty acids in the oil increases and that this increase is associated with a drop in the ignition temperature of the oil Therefore it is important to consider whether the temperature thresholds discussed in section 4 are appropriate for used oil as well as fresh oil The graph below shows the change in smoke flash and fire ignition points of oil with increasing free fatty acid FFA content Typical FFA concentrations for unused frying oil are between 0 05 and 0 08 or less Reference Bailey s Industrial Oil and Fat Products Volume 1 page 214 From the graph it can be seen that the FFA concentration must rise to around 2 before any significant change in ignition temperature occurs Free fatty acids Temperature F Figure G1 Smoke fire and flash points of miscellaneous crude and refined fats and oils as functions of the content of free fatty acids from Bailey s Industrial Oil and Fat Products Volume 1 page 212 Data is available in the literature relating time a
13. Food Ignition in Pan Elec Signal Processing Auto activation Non contact T sensor 4 22 Prevent Food Ignition in Pan No Signal Processing Mechanical Actuation Tech Class 21 The safety system monitors the pan temperature with a pan contact temperature sensor The mode of actuation is mechanical instead of electrical The temperature sensor used can be bi metallic piece that will bend at certain pre set temperature a magnetized piece that changes properties at certain temperature or an expandable liquid sensor This type of technology has been used as either a heat source regulating device or a one time shut off device PAN cota T TEMPERATURE Denso SWITH POWER TEMP POWER LEVEL Figure 4 21 Prevent Food Ignition in Pan No Signal Processing Mechanical actuation 4 23 Prevent Boil Dry Spill Over Temperature Sensor Tech Class 22 In this technology the temperature of cooking utensil is monitored The sensor technology can be a pan contact thermocouple or it could be an optical or non optical temperature sensor The basic element of this approach is the detection of a temperature signature for boil dry or spill over e g sharp increase of temperature after a constant temperature reading The controller is configured to shut off the temperature to the element or gas burner after the boil dry condition has been detected PAN CoN TAT TEMPERATURE ENSOR SHoT oF
14. Kinzoku Kogyo KK VARIOUS SENSORS 57 JP 4006325 An energy Temp sensor is installed within a downdraft duct behind burner When food overheat oil The energy sensor detected pre set radiation energy from cooktop turn off burner and stop blower Matsushita Electric Ind Corp 58 JP 7171061 T sensor is directly inserted to pan pot content T sensor is attached to an None alarm system that can generate synthesized voice to alert cooker of cooking fire danger when Tfood oil Tthres eg 200 C SENSORS ACTUATORS Patent Description Company No Number US 4710611 AT sensor for pan bottom T located at the center of an electric heat plate cooking hob Tsensor could be a thermistor liquid based Conical sensor housing shape meant to reduce dirt from entering sensor AB Electrolux Sweden US 3668372 Detailed design on how to mount the capillary type Tsensor using the capillary tube itself as the spring device that will maintain the contact of sensor head with cooking vessel bottom Robertshaw SiC Thin Film Thermistors US 5919385 Thermistor using RF sputtered SiC film developed specifically for cooking appliance Has been applied to detect Tpan bottom for gas cooktop Thermistor is connected to a controller that adjust gas valve for burner shows rapid thermal response Specifically for hob w halogen lamp as heat source and a ceramic cooktop which absorbs 40 of halogen radiation The T
15. PREVENT UNATTENDED COOKING WARNING AND CONTROL MOTION POWER SENSOR Effect on Cooking Process As long as user is around the cooktop there is none User can simmer some food and then leaves the room since it should be at lowest heat setting below which the system should actuate Need to be around when boiling hot water usually at higher heat settings Effect on Cooking Time As long as user is around the cooktop there is none If user simmers some food and leaves the room then it should be at lowest heat setting below which the system should actuate Effect of System on Consumer Behavior While Operating the Cooktop User will need to read the manual to learn that burner will manipulate heat when he she leaves cooktop area Limits availability or efficacy of marketed cooktop features None Ease of System Verification User can verify easily if system is on or off by turning the burner on at certain power level and leaving the room to see what happens Safety System Maintenance Cleaning the sensor surface is not more than wiping of the front casing cover which is part of the regular daily cooktop cleaning Power level sensor will most likely be located away from soil from cooking Cookware Applicability All cookware can be used with cooktop at any normal environment Range of Fire Incident Coverage Based on existing fire data If working properly will at least address unattended cooking 53 5 of fire incident from NFIRS NFPA data from
16. Technology Classes We collected additional information on the 7 technologies selected for evaluation This activity included interviews with vendors additional laboratory tests and discussions with Arthur D Little staff with relevant technology and or industry experience A draft report was prepared for review and comment by CPSC and AHAM representatives 3 3 4 Results 4 1 Patents Products Technologies Systems Concepts A complete list of the patents products technologies systems and concepts that we have identified that could potentially address surface cooking fires or be part of a system to address surface cooking fires is in Appendix A A number of these technologies were eliminated from additional consideration due to one or more of the following reasons e The technology had the potential to increase a safety risk to the homeowner e g it required the user to extinguish the flame manually or it required the homeowner to move closer to the flames in some way e The technology did not address a critical aspect of the surface cooking fire issue e g it was not appropriate for grease fires of any kind e We were unsuccessful in obtaining additional information about the technology e g we some information on a web site but received no response to phone calls e mails etc for additional information e The technology or approach was obviously impractical or not feasible for residential application A list of
17. an onto stove surface Sensor means unclear BUNKA SHUTTER COLTD OTHER OR UNKNOWN FIRE 26 JP 2045073 Water sprayed from surrounding pipe frame to cool and suppress fire After flame None DETERMINATION METHOD has subsided a metal plate covers pot automatically Sensor means unclear 27 Stovetop Hood installed magnet extinguisher No pressurized tank There is an explosive material insidq Williams Pyro Inc FireStop the powder ectinguisher canister that will explode when it fuse mechanism experience a threshold environmental temperature 28 US 4483314 Pull out blanket from drawer underneath the burner heat source Used to manually None smother fire 29 JP 10201871 Manual fire extinguishing sheet Fire extingusih agent is suspended in a flexible amp None 30 31 32 33 fusible encasing from polyethylene film When fire occurs drape sheet on stove to melt film and delivers extinguisher JP 9206393 Kitchen mat with incombustible material to smother fire manually DUSKIN CO LTD JP 9117329 Incombustible back panel for wall cover A passive wall attached on the wall behind the cooktop JMATSUSHITA ELEC to reduce the spread of cooking fire WORKS LTD JP 1015068 Fire Breaker Fuel Neutralizer Range hood act as a fire enclosure containment unit Drops down to cover entire cooking unit manually activated the powder extinguisher on the source of fire PREIGNITION OF FOOD OTHER Patent No Number
18. below the glass ceramic cannot be used to indicate pan temperature accurately Control suppliers are reluctant to provide additional information about the potential for the current pan detection sensors to be used as pot temperature sensors It appears that the thermal inertia in the glass ceramic is too great for the sensor to provide a reasonable indication of pan temperature There are two additional important issues for effectiveness that would need to be addressed One is the potential for the system missing a pre ignition condition due to the sensor being dirty or damaged The second issues is designing a way for the system to fail safe It is not obvious how to implement a self check that would prevent the range from operating if the sensor was not reading pan temperatures accurately Development needs and issues Currently the prototype systems do not meet all the requirements for commercial implementation The system used in the gas cooktop was the more successful The algorithm used appeared to successfully limit pan bottom temperature indefinitely to below the oil ignition temperature did not require any action from the user and did not appear to adversely affect cooking However it was not robust and would be easily damaged in the field The current implementation was excessively noisy The electric system did succeed in preventing ignition in our tests but the system was less satisfactory Both boiling water and searin
19. by Myun Baek Jeong 1 to the Home Appliance analyzing Temp gradient Hyeon Lim LG Electronics Inc AMCE Proceedings Oct 98 Gold alloy tracks for pot sensing Has transmitter amp receiver track detection by measuring amount of electromagnetic damping on Advanced Cookware Sensing System for _ track Detect vitroceramic T around heat zone thus cooking pot by 2 Vitroceramic Cooktops measuring specific resistance of the gold alloy track Mike Schwert Cherry Elec Products AMCE Proceedings Sep 99 A comment by a restaurant amp food industry consultant on the need Functional Fantasies Designing Dream for consumer input and consideration in the development of Rest amp Food Indust 3 Kitchens that Cooks cooking equipments form should follow function etc Jan Weimer Consultant AMCE Proceedings Sep 99 Paper on the development of an accurate and reliable gas sensors that can be cheap enough to be manufactured for the mass market The technology is based on Micro Electro Mechanical systems Accurate and Reliable Gas Sensors for the MEMS The company is in the process of developing a smaller 4 Mass Market less expensive NDIR gas sensor Brian R Kinkade lon Optics Inc AMCE Proceedings Sep 00 Description of a new micromachined water vapor sensor that was__ Ralph Fenner ow comes We seraror developed using the MEMS microelectromechanicas systems 5 Home Appliance Applications technique etc Hygrometrix Inc AMCE Proceedings Sep 00 A discussion on
20. fire data from NFPA CPSC phone survey and NASFM AHAM 1997 report Review on CPSC TC system on coil element cooktop and subsequent cooking tests by GHI Discuss Additional cost of safety system to Aug 1999 Report of Cooking Fires Working Group cooktop AHAM A detailed research to learn the sources of cooking fire based on equipment and user s behavior Used a survey form Ten Community Study of the Behaviors amp Profiles of People distributed to fire dept of 10 community over 6 months Involved in Residential Cooking Fires July 1998 period NASFM AHAM Report of statistical home fire data gathered from NFPA Study is conducted for fire data from 1980 to 1996 Has some data on sources of fire kitchen being the leading US Home Cooking Fire Patterns and Trends through 1996 area of origin Nat l Fire Protection Assoc AHAM Report of statistical home fire data gathered from NFPA ra Similar information as previous entry with the addition of a ld US Home Cooking Fire Patterns and Trends April 00 more detailed data eceived from 1993 to 1997 Nat l Fire Protection Assoc AHAM psioysindusiel Oe FatProdats et ea Bailey s Industrial Oil amp Fat Products point Y H Hui Tae or Fas ote usegintooa pot amaka tasn ana o orage 0 Table of Fats amp Oils used in food point Dept of agriculture Foa rasaois po TT Lia rstonering a edbeis Food Fats amp Oils point Inst Of Shortening amp Edible Oils k cost Anais of CPSC Range Control Prototype
21. get damaged when it impacted the cooktop surface Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down If the drop hood release mechanism is not working properly there is no indication that cooktop will not continue operating Safety system components might pose added risk to consumer The falling hood can catch or pinch user s body parts finger arm if they did not clear out of the way Can be modified by having an alarm that will alert user of hood actuation moments before it actually does Applicability across product types and product models Each cooktop model may require different design for functionally different models within a product type since they come in different dimensions The enclosing hood must have the appropriate dimension for each one of them Non hood installation such as island and downdraft versions need different solution Components system availability Need to develop all of the system s components Installation Needs special tradesmen specialist to install system Serviceability Needs additional training and new equipment to service system PREVENT UNATTENDED COOKING WARNING AND CONTROL MOTION SENSOR ONLY Effect on Cooking Process User cannot simmer boil some food and then leaves the room Effect on Cooking Time As long as user is around the cooktop there is none Effect of System on Consumer Behavior While Operating the Cookto
22. help to verify the operation of the safety system Safety System Maintenance Need additional procedures to clean the smoke detector and temperature sensor and to recharge the extinguisher tank check tank pressure etc Cookware Applicability Works for all types of cookware at any normal environment Range of Fire Incident Coverage Based on existing fire data Will detect more than 90 of cooking fire incidents since it will actuate whenever fire is occuring Percent of new product sales covered by this technology Will cover less than 90 of new product sales since non hood installations downdraft and island cooktop need different approach The degree of mitigation of fires addressed Will extinguish fire when it happens Effect of Safety System on Cooktop Performance After Actuation of System Will need significant cleaning and adjustment since a fire has occurred when safety system actuated Effect of Actuation on the Safety System Will need service technician help to return safety system to readiness recharge the extinguisher tank etc Potential for False Actuation Potential of false positive during high particulate cooking searing where the smoke sensor might trigger the alarm unnecessarily Can Operate Over product life w o failure safety factor of 2 Looks problematic but no data smoke sensor might get soiled and covered up by airborne cooking or grease particles and needs replacement Can operate within reasonably foreseeable
23. oSut Figure 4 9 Contain Manage Fire Active 4 11 Prevent Unattended Cooking Warning and Control Motion Sensor Only Tech Class 10 This technology is intended to require that a person be present while the cooktop is being used This approach uses a motion sensor to detect the presence of a user near the cooktop There are various possible locations for motion sensor but many patents reference the sensor on the front panel of the cooktop Slightly different types of algorithms are applied but in general the system sounds an alarm if no person is detected near the cooktop after a set amount of time The cook can return to the stove and reset the system without any effect on the cooking process However if no one responds to the warning alarm the control will adjust the hob accordingly e g reduce it or turn it off MOTION gt TIME f TME Pepoctisl IN POWs LEVEL WITH NO Monon Fee EXTENDED PERIOD Figure 4 10 Prevent Unattended Cooking Warning and Control Motion sensor only 4 12 Prevent Unattended Cooking Warning and Control Motion T Sensor Tech Class 11 Again this technology is intended to require that a person attend to the cooking process However this technology couples a motion detector with a temperature sensor so that the person is not required to be present unless the pan temperature is nearing a potentially pre ignition condition
24. on Rinnai Range 1000 800 T 600 2 gt T O a 5 Fe 400 200 meat added meat turned V PC center of steak 0 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge D24 Appendix E Technology Screening Scores Technologies Fire Deterrent Consumer Impact 1 Detect Extinguish Fire Fusible Parts Ooo o s5 S B m 4 6 Detect Fire Warning Only Optical T sensor __ _ 8 Contain Manage Fire Passive _ _ _ 9 Contain ManageFire Active U UOO Prevent Unattended Cooking Warning and Control 47 Motion sensor only Prevent Unattended Cooking Warning and Control 2 i 3 Detect Extinguish Fire Optical T sensor 4 i Motion T sensor Motion Power sensor Power level sensor timer Motion sensor only 15 Prevent Unattended Cooking Warning Only 27 lonon r pomor Power level sensor timer Prevent Food Ignition in Pan Elec Signal Processing Select Mode or T T sensor contacts pot Prevent Food Ignition in Pan Elec Signal Processing Select Mode or T Non contact T sensor Prevent Food Ignition in Pan Elec Signal Processing Auto activation T sensor contacts pot Prevent Food Ignition in Pan Elec Signal Processing Auto activation Non contact T sensor Mechanical actuation 18 Technology Do Nothing NOTE Technologies highlighted in Red are technologies that fall inside the Preferred Region Technologies highlighted in Blue are te
25. optical sensor technology for fire detection Basic physics of sensor mechanism is well understood but actual design Optical Fire amp Security Technology Sensor of cost effective detectors reliable under an extreme range of Principle amp Detection Intelligence environment is still a highly demanding task P Reyser G Pfister Cerberus Ltd IEEE 1991 A short discussion on limitations of various current fire detection 7 Fire Detection The Least of Our Problems jand their tendencies to cause false alarms Andrew Morgan Technologies Ltd A description of a new development of a fire detection system that fee Detectan w cantina uasan combined two sensors ultrasound and microwave Doppler sensor IEEE Ultrasonic Microwave Doppler Sensor to reduce the incidence of flase alarms H Ruser V Magori Siemens AG Symposium 1998 Thermistor using RF sputtered SiC film developed specifically for cooking appliance Has been applied to detect Tpan bottom for gas IEEE Transactions cooktop Thermistor is connected to a controller that adjust gas Takeshi Nagai Matsushita Housing on Industry SiC Thin Film Thermistors valve for burner shows rapid thermal response Masahiko Itoh Products Applications Paper describing the technology applied on the development of IEEE Transactions Temperature Control for Food in Pots on Bosch s sensor cooktop The temperature sensor used is a Uwe Has Dimitar Bosch Siemens DIAS on Industry 10 Cooking Hobs thermopile optical sensor Was
26. simmer Potential for false negative where sensor might mistaken pets curtains or small children can be eliminated using appropriate sensor data analyzing algorithm e Can Operate Over product life w o failure safety factor of 2 Looks good but no data e Can operate within reasonably foreseeable misuse conditions durability Looks good but no data e Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop will not work if no signal from motion sensor is detected e Safety system components might pose added risk to consumer None was expected e Applicability across product types and product models Developed to be applicable for all cooktop systems e Components system availability Most parts are available off the shelf or has been manufactured at high volume at low cost e Installation No added effort than installing conventional range e Serviceability Some training or new equipment is necessary for servicing the sensor PREVENT UNATTENDED COOKING WARNING AND CONTROL MOTION T SENSOR e Effect on Cooking Process Should be none since high temperature cooking is still possible as long as the cook is near the cooktop And simmering should still be possible since cooktop should only manipulate heat source when food temperature is significantly higher than simmering boiling temperature e Effect on Cooking Time Should be none if user is around duri
27. some technology classes we grouped many products patents and ancillary technologies Other technology classes contained only one patent or one concept 3 3 Identify Review and Develop Data to Support Technology Evaluation We identified reviewed and developed data to support the technology evaluation process We reviewed a large amount of literature including e the reports covering the cooking fires work sponsored by the CPSC e the analyses conducted by the AHAM Cooking Fires Working Group and the memorandums covering the minutes of their meetings e fire statistics generated by the National Fire Protection Association NFPA and National Fire Incident Reporting System NFIRS and summarized by NFPA e studies conducted by the National Association of State Fire Marshals Cooking Task Force e AMCE Conference Proceedings e JEEE transactions e data on edible oils from a variety of sources e AHAM test reports covering work conducted as part of the 1986 Food Fire Test Program In addition we reviewed videos illustrating grease fires and safe cooking techniques that AHAM made available to us To deepen our understanding of industry issues and concerns we met with appliance manufacturers to discuss their product lines product development process technology needs technology evaluations relevant tests concepts related product development programs product trends industry concerns and safety requirements The specific el
28. sound the alarm When the smoke is accompanied by a temperature exceeding a threshold level at the area surrounding the cooktop it will turn off the heat source and either release fire extinguisher material and or contact outside services 911 or fire department PATINGUISRING AGERET SPRAY NozzL ALARM EXTINGUISH os MOE gt THRESHOLD Terese RVR SMOKE gt THRESHOLD Figure 4 4 Detect Extinguish Fire Smoke T sensor 4 6 Detect Fire Warning Only Non optical Temperature Sensor Tech Class 5 This technology warns of the presence of fire but does not actuate a fire extinguishing system The presence of a fire is detected by a non optical temperature sensor such as a thermocouple diode or thermistor located near the cooktop usually in hood to detect fire When a threshold temperature is exceeded an alarm will warn the user of a fire TIME Figure 4 5 Detect Fire Warning Only Non optical T sensor Detect Fire Warning Only Optical Temperature Sensor Tech Class 6 Again as with Technology Class 5 this is a warning system without a fire extinguishing system In this case an optical temperature sensor such as and infra red IR sensor is used to monitor the temperature surrounding or on top of the cooktop When the temperature exceeds a threshold an alarm is actuated TIME ALARM Ty THRE SHoOLI gt Fig
29. sssssssnnnnnnrnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn A 1 Appendix B Technologies Eliminated in Initial Screen sassssssnnnnnennnnnnnnnnnnnnnnne B 1 Appendix C Cooking Process Definitions ccccccssesseseeeeeeeeeeeeeeeeeeeeeeeeeeeneeees C 1 Appendix D Temperature Measurements from ADL Cooking Tests D 1 Appendix E Technology Screening SCOPreS ccccccsssseeeeeeeeeeseeneeeeeeeneeeeeeeeeeeneeees E 1 Appendix F Basis for Technology Screening SCOLreS cccccscesseeeeeeeseeeeeteeeneees F 1 Appendix G Used Oil Analysis and Testing ccccsssseeeeesssneeneesseneeneenseneenennes G 1 List of Figures Figure 4 1 Figure 4 2 Figure 4 3 Figure 4 4 Figure 4 5 Figure 4 6 Figure 4 7 Figure 4 8 Figure 4 9 Detect Extinguish Fire Fusible Parts ese eeseesesseeeeseecsseceseessneeenees Detect Extinguish Fire Non optical T sensor 0 0 ceeceeeeeseeeeeeeeeeenees Detect Extinguish Fire Optical T Sensof cece eeeeeeeeeeeeseeesseeeeeeenees Detect Extinguish Fire Smoke T Sensor eeeeeseesecsteceseeeeeeeenees Detect Fire Warning Only Non optical T sensor ceeceeeeeeseeeeeeeees Detect Fire Warning Only Optical T sensor ec ee eeeceeeeeeeeeeeeeeees Detect Fire Warning Only Smoke Sensor ou eee eeeeeeeseceseeeeeeeenees Contain Manage Fire Passives lt ccca cotacasct se ycaessseceonas space ccsoattodaaneqeeneiantone Contain Manage Fire ACU yes iwccssivssjecesa
30. temperature sensor e g thermocouple The controller is configured to limit the temperature at the bottom of the pan to a threshold that is independent of the cooking mode The threshold is selected to balance the requirements of various cooking modes and the limit to avoid ignition of cooking materials A microprocessor control adjusts the heat input to the pot based on the pan bottom temperature This system prevents the temperature at the bottom of the pan from rising to a level that could cause ignition of cooking materials Megero Esso mNTRO S PAN CONTIENT TEMPERATURE SENSOR 7 NME Figure 4 19 Prevent Food Ignition in Pan Elec Signal Processing Auto activation T sensor contacts pot 4 21 Prevent Food Ignition in Pan Elec Signal Processing Auto activation Non Contact T Sensor Tech Class 20 In this configuration the safety system monitors the pan temperature with a non contact temperature sensor e g IR sensor The controller is configured to limit the pan to a threshold that is independent of the cooking mode The threshold is selected to balance the requirements of various cooking modes and the temperature limit to avoid ignition of cooking materials A microprocessor control adjusts the heat input to the pot based on the pan temperature This system prevents the pan temperature from rising to a level that could cause ignition of cooking materials Figure 4 20 Prevent
31. the build up of a layer of grease or oil on the sensor surface but the higher operating frequencies of the microwave and RF detectors mean their signals are not significantly affected by the presence of grease on the surface of the device More sophisticated systems also use the Doppler effect to measure the change in frequency in the return pulse This method increases the sensitivity of the system The systems generally have a wide and narrow user selectable FOV setting Rotating the antenna configures the selectable FOV for narrow or wide The maximum range of the unit is determined by the power of the transmitter The typical ranges and FOV of active systems can be seen below Typical units have a 5 year warranty Aside from the mechanical relays in the unit the electronics package can last at least 10 years z E E zy o RZ zg as 11 3 4m 3 4 RANGE 5 1 5m 3 4 RANGE Technology Development Status Systems that would prevent unattended cooking though warning and control using a motion sensor only are covered in 4 US patents There is one Japanese patent that refers to the use of a motion detector plus one additional input either power level or heat sensor to control heat input to the cooktop The warning only system is a concept There are no patents for this approach We are not aware of any commercial products using these safety systems Motion detectors alone are common components in home security systems and
32. the technologies that were eliminated from additional consideration and the reasons for doing so is included in Appendix B The remaining technologies were clustered into technology classes so that they could be more effectively evaluated These classes are described in the following section 4 1 4 2 Technology Classes Table 4 1 lists the technology classes that we used to organize the hundreds of patents products technologies systems and concepts identified in the first task Table 4 1 Fire Mitigation Technology Classes Detect and Extinguish Fire Fusible Parts Non optical Temperature Sensor Optical Temperature Sensor Smoke amp Temperature Sensor Detect a Fire Provide Warning only Non optical Temperature Sensor Optical T Sensor Smoke Sensor Contain or Manage Fire Passive Active Prevent Unattended Cooking Warning and Control Motion Sensor Only Motion Sensor and Power level Motion Sensor and Temperature sensor Power level Sensor and Timer Prevent Unattended Cooking Warning Only Motion Sensor Only Motion Sensor and Power Level Power Level sensor and Timer Prevent Food Ignition in Pan Electronic Signal Processing Mode Selection Pan contact Temperature Sensor Electronic Signal Processing Mode Selection Non contact Temperature Sensor Electronic Signal Processing Auto Control to Temperature Threshold Pan contact Temperature Sensor Electronic Signal Proce
33. to 360F or above and used to fry ten batches of frozen french fries In between each batch the oil temperature was allowed to drop to around 300F After the tenth batch three 100ml samples of the used oil were then heated until ignition in a stainless steel frying pan The resulting oil ignition temperatures and the ignition temperatures for unused oil from the earlier tests are given in the table below Test conditions Ignition temperature Oil type Pan type Range F used stainless steel Rinnai 700 730 735 fresh stainless steel Rinnai 750 fresh cast iron Rinnai 730 fresh aluminum Rinnai 680 fresh stainless steel electric 760 fresh cast iron electric 740 fresh aluminum electric 760 These test results are consistent with the findings in the literature and show that the ignition temperatures in the used oil tests lay within the range of ignition temperatures noted for fresh oil
34. will most likely located away from grease and food build up under the cooktop surface Cookware Applicability All cookware can be used with cooktop at any normal environment Range of Fire Incident Coverage Based on existing fire data Depending on the timer duration and limiting power level selected there is probability that system might address 60 of fire incident Percent of new product sales covered by this technology Power level sensor for gas burner needs more development The degree of mitigation of fires addressed To prevent pre ignition condition Effect of Safety System on Cooktop Performance After Actuation of System If system works as intended then no fire will ever occur so no cleaning or adjustment is necessary after system actuation Effect of Actuation on the Safety System User needs to reset system by pressing a button or turning a control knob Potential for False Actuation Potential for false negative if food oil was already hot when burner was turned on Can Operate Over product life w o failure safety factor of 2 Looks good but no data Can operate within reasonably foreseeable misuse conditions durability looks good but no data Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Burner will not turn on when no signal from power level sensor is received Safety system components might pose added risk to consumer None is expected Appl
35. work for all models for one product type for vented or non vented hood and under cabinet hood or free standing ones but cannot work for downdraft or island installations where no hood is available Components system availability Most part are available off the shelves or have been manufactured in high volume at low cost Installation Need specialist help to install Serviceability Need specialist help to service extinguisher tank DETECT EXTINGUISH FIRE NON OPTICAL T SENSOR Effect on Cooking Process None system only actuates after a fire has occurred Effect on Cooking Time None system only actuates after a fire has occurred Effect of System on Consumer Behavior While Operating the Cooktop None system only actuates after a fire has occurred Limits availability or efficacy of marketed cooktop features None Ease of System Verification Some systems available in the market automatically verifies system readiness Still need user to manualy verifies pressure level of extinguisher canister Safety System Maintenance User maintenance requires significant additional procedures to make sure that temperature sensor is cleaned and fire extinguisher is fully charged Cookware Applicability All cookware can be used with cooktop at any normal environment Range of Fire Incident Coverage Based on existing fire data Will address all fire incident since it will actuate whenever fire is detected Percent of new product sales covered by this
36. 1994 1996 Percent of new product sales covered by this technology Will work fine with electric cooktop but need some development for he power sensor for gas burner The degree of mitigation of fires addressed Will prevent fire from occurring if working properly Effect of Safety System on Cooktop Performance After Actuation of System None fire will not even start so cooktop should be ready to work normally again after safety actuation Effect of Actuation on the Safety System Cooktop should reactivate automatically when user s presence is detected Potential for False Actuation Potential for false negative if food oil is already hot when burner was turned on Potential for false negative where sensor might mistaken pets curtains or small children can be eliminated using appropriate sensor data analyzing algorithm Can Operate Over product life w o failure safety factor of 2 Looks good but no data Can operate within reasonably foreseeable misuse conditions durability Looks good but no data Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop will not work if no signal from motion sensor or power level sensor is detected Safety system components might pose added risk to consumer None was expected Applicability across product types and product models Will need more development to apply for gas cooktop specifically for the power level sensor
37. F oiL PRY LONDONON Figure 4 22 Prevent Boil Dry Spill Over T sensor 4 24 4 3 Screening Criteria We developed screening criteria for these technologies based on two sets of considerations 1 The potential impact of the technology on the cooking performance operability reliability durability safety and manufacturability installation service of the cooktop or range and 2 The potential effectiveness of the technology to mitigate surface cooking fires All the criteria and metrics used to screen and ultimately evaluate the surface cooking fire mitigation technologies are listed below 1 Cooking Performance Effect on Cooking Process High Works well with all surface cooking functions Medium One cooking function is eliminated or negatively affected Low More than one cooking function eliminated or negatively affected Effect on Cooking Time High None Medium Some Less than 10 Low Significant Equal or More than 10 2 Cooktop Operability Effect of System on Consumer Behavior While Operating the Cooktop High New user will not notice any difference in operating procedure compared with conventional cooktop Medium New user will notice difference s in procedure but it will be intuitive enough that he she will not need a manual to operate Low New user will need to learn new skills through a product manual in order to operate cooktop 4 25 Limits a
38. No data looks problematic sensor window might get soiled w grease and food that might require replacement Some model requires sensor to move up and down from cooktop s surface this might get soiled and jammed Can operate within reasonably foreseeable misuse conditions durability No data looks good Sensor is located away from the pot and pans traffic during cooking Chance of impact with cooking pot pan is minimal Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop might still be able to work even though safety system is off Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work on all models of the same type Components system availability Most parts need development Installation No different than conventional cooktop Serviceability Needs new training and some new equipment ae ree FOOD IGNITION IN PAN NO SIGNAL PROCESSING MECHANICAL ACTUATION Effect on Cooking Process High temperature cooking searing is negatively affected Effect on Cooking Time Most likely will affect more than 10 percent of cooking time Most mechanical actuation devices bimetal strip or expansible liquid sensors will react slower to temperature fluctuation which might cause it to delay the on off cycle time and thus prolong cooking time Effect of System on Consumer Behavior
39. ROPRO CESSOR TO DETERMINE COOKING STATE AND ACTION OF COOKTOP AUTOMATIC ACTIVATION OF SAFETY SYSTEM MEASURE PAN TEMP W NON CONTACT SENSOR SELECT T OR COOKING MODE 33 US 4994652 Use cook mode switch 2 T sensors are used dependent on type off cooking selected for Fissler GmbH MEASURE PAN TEMP w ELECTRIC roasting T contact T dependent resistor on the underside of ceramic plate and for other Germany W CONTACT OR NON through pot wall using contact and or IR sensor Signal fed to controller that ll manipulate heat CONTACT T SENSOR source depending on mode 34 JP 11118153 A design for a reliable temperature sensitive metal and a magnet that can actuate gas valve in Paloma Ind Ltd case of fire At pre set Tthres device will close valve 35 JP 3236520 Gas valve is opened w spring force TC for Tpan is in contact w an electromagnet attached Matsushita Electric MEASURE PAN BOTTOM T to on off gas valve switch When Tpan gt Tthres TC produce electricity which attracted the Ind Co LTD NO SIGNAL PROCESSING electromagnet and compress the spring on the gas valve and closes it USE ELECTROMAGNETIC 36 JP 3236519 Electromagnet is the T sensor for pan bottom As Tpan increases to Tthres sensor loses its Matsushita Electric SENSOR JP 8254320 JP 11094245 property and releases the spring loaded gas valve and turns burner off TC for pan bottom generate electricity to a coil w electromagnet This electromagnetic force kept gas valve
40. Technical Practical and Manufacturing Feasibility of Technologies to Address Surface Cooking Fires Final Report Report to United States Consumer Product Safety Commission May 22 2001 Arthur D Little Inc Acorn Park Cambridge Massachusetts 02140 2390 Reference 72931 ACKNOWLEDGEMENT We would like to thank the Association of Home Appliance Manufacturers who have supported the expanded scope of this report with funding from their wholly owned subsidiary the Appliance Research Consortium ARC By facilitating meetings with their member companies AHAM provided Arthur D Little and the CPSC access to information on technologies products industry issues and perspectives relevant to the surface cooking fires program Table of Contents 1 Background rr oi ch coin iis ta aeea aaa eaa ra EEn ae a E E aaaea 1 1 2 ODI6Ctive E eek ih eee ene 2 1 3 PAD POAC ices T A A einen 3 1 3 1 Identify Patents Products Technologies Etc eee eescesseceeeseeeeeseeeeeeees 3 1 3 2 Structure Patents Products into Technology Classes ceseceeeeeeeeeteees 3 1 3 3 Identify Review and Develop Data to Support Technology Evaluation 3 1 3 4 Develop Evaluation Criteria sc ccsicsccsesccssetiasensd dents sdsascosvtecedsseceasneassd cat seston 3 2 3 5 Screen Technology Classes by Evaluation Criteria eeeeseeeeseeeenees 3 2 3 6 Select Technology Classes for Detailed Evaluation e ce eeeeeeeeeeeteees 3 3 3 7 Eva
41. When this reaches 330 C 626 the element starts to cycle on and off 1 sec on 6 sec off If the temperature reaches above 360 C 680 F for more than 2 seconds the element shuts off completely In addition spring loaded pan contact temperature sensors are common on gas tables i e two burner gas fired countertop cooktop units sold in Japan The controls on the Japanese units incorporate a mode switch to select the appropriate algorithm for frying boiling etc Potential Impact of Technology on Product Performance and Consumer Behavior This technology should not require changes to consumer behavior but it could impact cooking processes and or cooking time Ideally as described in Section 4 4 2 there is a significant gap between the pan temperature associated with pre ignition conditions and the pan temperatures required for standard cooking processes If the pan contact sensor is well insulated from the burner or electric element and if it has good contact with the bottom of the pan it will reflect the actual pan bottom temperature and can be used in straightforward way in a cooktop controller The engineering implementation of the pan contact sensor will strongly affect the efficacy of this approach If the contact sensor does not contact the pan well or if it is not well shielded or insulated from the burner itself the sensor output would not accurately reflect the pan bottom temperature If the sensor indicates a temp
42. While Operating the Cooktop None since cooktop will constantly manipulate heat source to maintain temperature settings selected Or it will maintain a limiting high temperature automatically regardless of the heat setting selected Limits availability or efficacy of marketed cooktop features None Ease of System Verification Need service technicians to verify system operation Safety System Maintenance User maintenance requires few additional procedures to clean up the temperature sensor regularly from grease or food soil build up Cookware Applicability Some cookware materials or shape can compromise safety system performance since the sensor will need to be in contact to the cooking vessel e g glass ceramic ware cookware with concave bottom Range of Fire Incident Coverage Based on existing fire data Will address more than 40 of cooking fire incident since it will avoid the occurrence of overheated foodstuff or cookware Percent of new product sales covered by this technology Will be difficult to apply on smooth top cooktop Ceran so will probably cover between 40 90 of new product sales The degree of mitigation of fires addressed Prevent cooking fire Effect of Safety System on Cooktop Performance After Actuation of System None no adjustment or cleanup necessary after safety system actuation since it prevents fire from ever occurring Effect of Actuation on the Safety System Since cooktop will continuously manipulate heat to keep fo
43. above except that it is potentially less effective in preventing fires but it may be less restrictive on consumer behavior as well 5 Prevent Unattended Cooking Warning and Control Motion Power sensor Tech Class 12 This approach has the same objective as the use of a motion sensor alone but the addition of a power level sensor is an effort to allow some cooking processes to proceed unattended One concern with the approach is that it will require a level of effort to implement on a gas system In addition because it allows some cooking to take place unattended it may be less effective in mitigating fires than some other technology options 6 Prevent Unattended Cooking Warning and Control Power level sensor timer Tech Class 13 This approach scores exactly the same as Technology Class 12 with the timer analogous to the motion detector requiring the presence of the cook near the rangetop 4 6 Selected Technologies This screening task was to provide a guideline for eliminating some technologies from further consideration and selecting others for detailed evaluation It was not intended to be used followed blindly We looked at technologies that did not score well and considered whether there was any opportunity for improvements in effectiveness or impact based on additional development work We also looked at the set of technologies that were being selected to determine whether they represented a reasonable por
44. aches could be similar to the ignition switches currently on gas ranges and cooktops In this case the knob position may need to be calibrated to the nominal heat input to the burner Overall the engineering issues are straightforward to address The consumer issues are much less clear 4 48 4 7 3 Prevent Unattended Cooking Warning and Control Power level sensor timer Tech Class 13 Description Overview A simple timer and power level sensor could achieve the same objective as motion sensor coupled with a power level sensor In the configuration of Technology Class 13 a timer would sound a warning at pre determined intervals potentially related to power input level The cook would need to press a manual re set button to indicate his her presence near the range With the timer the unit would provide an alarm even if the cook were nearby Some range users could perceive this requirement as a nuisance As with the previous three technologies the timer and power level sensor is intended to have an impact on consumer behavior It will require the cook to be present near the range during the cooking process If the cook does not activate a re set button the power input to the range is either modulated or shut off This system scores highly in safety system effectiveness because is intended to prevent a fire from igniting is applicable to most product classes and can be made to be fail safe The basic assumption here is that at
45. adjusts the heat input to the pot based on the cooking mode selected and the pan bottom temperature This system prevents the temperature at the bottom of the pan from rising to a level that could cause ignition of cooking materials Micterencessece con Teas c Mope se ecTiony gt PAN CONTACT TEMPEPATURE SENEO TIME Figure 4 17 Prevent Food Ignition in Pan Elec Signal Processing Select Mode or T T sensor contacts pot 4 19 Prevent Food Ignition in Pan Elec Signal Processing Select Mode or T Non contact T sensor Tech Class 18 In this configuration the safety system monitors the pan bottom temperature with a non contact temperature sensor e g IR sensor The controller is defined by a user selected cooking mode e g searing boiling frying or a specified cooking temperature A microprocessor control adjusts the heat input to the pot based on the cooking mode selected and the pan temperature This system prevents the pan temperature from rising to a level that could cause ignition of cooking materials MICROPROCESSOR CoHTROLS Figure 4 18 Prevent Food Ignition in Pan Elec Signal Processing Select Mode or T Non contact T sensor 4 20 Prevent Food Ignition in Pan Elec Signal Processing Auto activation T Sensor Contacts Pot Tech Class 19 In this configuration the safety system monitors the pan bottom temperature with a pan contact
46. ailability or efficacy of marketed cooktop features None Ease of System Verification Needs service technician s help to verify system s operation Safety System Maintenance Needs significant additional procedure to clean the optical sensor change battery etc Cookware Applicability Dependent on location of of sensor it can mistake gas flame from burner or radiant heating element as fire condition Cooking using small pot pans where a radiant heat source is not fully shielded from the view of the sensor might affect system Range of Fire Incident Coverage Based on existing fire data Will be between 40 90 of cooking fire incident due to the fact that this system currently not applicable for gas ranges Percent of new product sales covered by this technology Will not work for gas cooktop since heat from burner will be mistaken as cooking fire probably the same with radiating electric heat element The degree of mitigation of fires addressed Warning only Effect of Safety System on Cooktop Performance After Actuation of System Since there is high probability that fire has commenced when the system is triggered the cooktop can be damaged from the high heat due to no provision to quickly extinguish the fire once it is detected Even if the user act quickly and extinguish the flame w a portable fire extinguisher clean up might be necessary Effect of Actuation on the Safety System User might have to reset the alarm once the fire has bee
47. al signal processing auto activation T sensor contacts pot Description Overview These systems work on the basis of limiting the temperature at the bottom of the pan so that the ignition temperature of the pan contents is never reached This process is automatic and requires no intervention from the user There are two critical aspects of the technology 1 the pan contact temperature sensor and 2 the algorithms used to differentiated standard cooking conditions from pre ignition conditions Technology Development Status Two prototype systems exist both developed on behalf of the CPSC One is for an electric cooktop the other for a gas cooktop e CPSC gas system This measures temperature using a spring loaded thermocouple partly shielded from the flame which makes contact with the pan base slightly to one side of the burner When the thermocouple reading reaches 590 F the burner switches to a low setting When the temperature drops below 590 F again the burner switches back to its original firing rate previously set using the knob on the range 4 50 e CPSC electric system This uses three thermocouples spaced roughly equally around a circle about 2 inches from the center of the electric ring The thermocouples which are spring loaded poke up between the gaps in the element and need to be carefully positioned so as not to contact the element The control algorithm uses only the maximum of the three temperature readings
48. anges centered semi shielded Energy International Inc CPSC Study of Tech for Detecting Pre ignition CPSC work to determine pre ignition condition for food related cooking Conditions of Cooking Related Fires Assoc firescusing multiple sensors such as smoke temperatures cooking Erik L Johnsson 2 w Elec Ranges Phase Report alcohols and hydrocarbons NIST Study of Tech for Detecting Pre ignition Conditions of Cooking Related Fires Assoc Review on the CPSC three unshielded TC cooking fire solution for Han Lim 3 w Elec Ranges Phase IV Report electric coil cooking element Describe designs and coking tests results CPSC CPSC Summary of NIST CPSC work on technical solutions for food related Study of Tech for Detecting Pre ignition cooking fires Determination of pre ignition conditions development amp Conditions of Cooking Related Fires Assoc test of prototype TC based solution conclusion pre fire detection Erik L Johnsson 4 w Elec Ranges Final Report system is physically feasible and merits further exploration NIST Practical Work w an electric coil range Sharon Franke equipped w an experimental TC based Result review of the GHI cooking tests on the El CPSC TC based Good Housekeeping 5 preignition control system cooking fire prevention solution for electric coil heating element Institute Range Fires Characteristic Reported in Report on statistical data obtained from NFPA NFRIS on home fires National Fire Data and a CPSC Spec
49. attached to T sensitive metal open When cooker gets hot T sensitive metal loses its magnetic permeability and valve is closed Else when thermoelec Force of TC has lowered valve also closes TC for pan bottom is combined with a bimetal switch and a temperature fuse These sensors are all combined in series to create a safety valve circuit to connect TC with the solenoid safety valve Ind Co LTD Paloma Ind Ltd RINNAI CORP JP 11094258 US 4217481 US 2786930 Tsensor using bimetal switch is connected in series w a TC pilot amp safety valve constituting an electrical closed circuit It is also connected to a T fuse to turn off gas Tthres No need for dry cell Electric cooktop with 2 cooking zones boiling amp roasting Each hot plate has a Tsensor For boiling zone the temperature range is between 40 140 deg for boiling amp warming For roasting temperature range is between 80 270 deg C Sensor uses expansion liquid amp capillary tube to connect thermostat Cooktop element or burner has a T sensor made of expansible thermosensitive material fluid connected with a capillary tube to a mechanical power gas controller to control the tem ture of the cooking vessel which is in contact with the Tsensor Hitachi Hometec Ltd None Robertshaw Thermal Eye or Tsensor using expandible thermosensitive liquid within a capillary tube Used to control the Burner w a Brairjtemperature of cooking vessel Robertshaw Ctr
50. automatic door openers 4 46 Potential Impact of Technology on Product Performance and Consumer Behavior This approach will have a significant effect on consumer behavior We anticipate that a significant number of range users currently leave the kitchen during certain cooking functions such as boiling water in a kettle simmering sauces simmering stews or soups canning or bringing a pot of water to a boil The warning and control system motion sensor only requires attendance whenever the cooktop is operating or the system modulates the heat input to the pot The warning only system motion sensor only provides a reminder to attend to the cooking but there is little consequence if the warning is not heeded like the warning bell in a car to fasten the seat belt The warning and control system that uses a power level sensor as well as the motion sensor would allow some low power input functions such as simmering sauces to proceed unattended If the user does attend to the cooking process there would be no impact on cooking time If however the user does not attend to the warnings and the system modulates or shuts off the heat input to the range cooking times will obviously extend None of these approaches would affect other cooktop features or cookware applicability There is minimal system maintenance required The motion detector could be applied to any type of product It would not add any installation requirement or significa
51. aving the area of the fire and calling the fire department We wanted to be consistent with this recommendation e Fire extinguishing technologies that were not intended to address oil or grease fires were eliminated from consideration e We used the statistics to estimate the potential effectiveness of certain fire mitigation approaches These numbers are only general estimates they are useful for evaluating the relative impact of technologies We averaged the varied numbers from the various reports as follows Requiring someone to attend to cooking was estimated for the purpose of comparison to mitigate 65 70 of surface cooking fires Preventing cooking materials from igniting was estimated for the purpose of comparison to mitigate 72 of gas surface cooking fires and 77 of electric surface cooking fires The total effectiveness of a technology intended to prevent the ignition of cooking materials is also dependent on the applicability of the 4 35 technology to specific product types and the sales volume of the applicable product types Data used on product types is included in Section 4 4 5 4 4 4 Reliability Durability The ANSI Z21 UL 858 STP Cooking Fires Working Group outlined the reliability durability requirements for any system that would be associated with a range or cooktop We considered these requirements in our analysis of the various fire mitigation technologies For the most part there was insufficient data to d
52. ble pre ignition indicator for the combustion of cooking materials on a range top From this work the most consistent measurable pre ignition indicator was concluded to be pan temperature Follow on phases to this work led to the design and early development of a thermocouple based control system to limit pot temperature to a level safely below a threshold pre ignition condition Separately other technologies have been developed to address surface cooking fires For example a variety of US companies offer automatic fire extinguishing systems for residential cooking applications In addition gas fired cooktops are made and sold in Japan that offer a temperature control function that will modulate or shut off to prevent overcooking burning and overheating of deep frying oil Other technologies have been developed that were not intended to address surface cooking fires but are intended to monitor and control pot temperature For example a European appliance manufacturer offers a cooking control system that remotely monitors pot temperature with an infra red sensor and controls the heat input rate accordingly The patent literature is full of systems approaches technologies and concepts to address cooking fires US appliance manufacturers are deeply concerned about a the potential effectiveness of these types of technologies to reduce the incidence of cooking fires and b the potential impact of these technologies on the cooking performance ope
53. bly affected cooking time by less than 10 e Effect of System on Consumer Behavior While Operating the Cooktop None since user will not even be aware that safety system is actuating e Limits availability or efficacy of marketed cooktop features None e Ease of System Verification Need service technicians to verify system operation e Safety System Maintenance User maintenance requires few additional procedures to clean up the temperature sensor regularly from grease or food soil build up e Cookware Applicability Some cookware materials or shape can compromise safety system performance e g glass ceramic ware cookware with concave bottom e Range of Fire Incident Coverage Based on existing fire data Will address more than 40 of cooking fire incident since it will avoid the occurrence of overheated foodstuff or cookware e Percent of new product sales covered by this technology Multiple designs applicable for gas and solid or coil electric element cooktops Has some design for smooth top Ceran gold alloy track but the application might be more difficult for a reliable means to gauge pot content temperature e The degree of mitigation of fires addressed Will prevent cooking fire from occurring e Effect of Safety System on Cooktop Performance After Actuation of System None no adjustment or cleanup necessary after safety system actuation since it prevents fire from ever occurring e Effect of Actuation on the Safety System None system w
54. categories 1 criteria that reflected the effectiveness of the technology to mitigate surface cooking fires and 2 criteria that reflected the potentially negative impact of the technology on the performance operation reliability safety of the cooking system 3 5 Screen Technology Classes by Evaluation Criteria As an initial screen we evaluated each technology class with respect to the agreed upon evaluation criteria and metrics The evaluation scores for each technology class were tallied A scatter plot of fire mitigation effectiveness versus impact on product value was generated for the set of technologies Two additional technology classes were evaluated as a process check do nothing i e make no change to range add no fire suppression technology and add smoke alarm only 3 2 Technologies that had comparatively low effectiveness or excessive negative impact on product value were eliminated from more detailed evaluation 3 6 Select Technology Classes for Detailed Evaluation The remaining technologies were screened for the potential to improve their effectiveness or decrease their impact on product value Some technologies had inherent limitations Others were found to have limitations in their current implementation but had potential to be improved with additional research and development or with the application of other known technologies We selected 7 technologies for detailed evaluation 3 7 Evaluate Selected
55. center PC center of steak 600 800 Time s PBE pan bottom edge 1000 1200 1400 TC1 TC2 and TC3 built in thermocouples 1600 Searing Steak in Aluminum Pan on CPSC Electric Range 1000 800 600 Temperature F 400 200 meat turned meat added PC center of steak 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge 1C1 TC2 and TC3 built in thermocouples D20 Searing Steak in Cast Iron Pan on CPSC Electric Range 1000 800 c 600 2 5 o 2 400 meat turned 200 meat added PC center of steak 0 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge 1C1 TC2 and TC3 built in thermocouples D21 Searing Steak in Stainless Steel Pan on Rinnai Range 1000 800 600 Temperature F 400 meat turned 200 meat added i T enon PC center of steak 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge D22 Searing Steak in Aluminum Pan on Rinnai Range 1000 800 T 600 2 gt T o p E AAA Fe 400 y a 200 meat added meat turned i PC center of steak 0 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge D23 Searing Steak in Cast Iron Pan
56. chnologies that fall at the border of the Preferred Region Ooo 3 O 33 380 Oo B Partial Partial Score Score Efficacy of Others Technology as Consumer No Classification of Cooking Impact Value 1 2 Detect Extinguish FireNon opticalTsensor 3 4 0 3 6e 62 2 C O 82 m Stage of technology 7 3 in development by CPSC Appendix F Basis for Technology Screening Scores F 1 DETECT EXTINGUISH FIRE FUSIBLE PARTS Effect on Cooking Process None system only actuates after a fire has occurred Effect on Cooking Time None system only actuates after a fire has occurred Effect of System on Consumer Behavior While Operating the Cooktop None system only actuates after a fire has occurred Limits availability or efficacy of marketed cooktop features None Ease of System Verification If pressurized extinguisher is used a pressure indicator is installed so user can verify manually Fusible part is just a material with a certain melting point unlikely to change this property within its operating condition Safety System Maintenance User require significant additional procedures parts e g extinguisher material refilling that might require specialist s help Need to clean up additional part within the hood Cookware Applicability All cookware can be used with cooktop at any normal environment Range of Fire Incident Coverage Based on existing fire data Will address all fire incident sinc
57. chure Ecowatt Schweitz AG Nouveau Cooking Conduspeed cooktop Ceramic cooktop w T sensor Web printout 7 National Fireproofing Co Fire Breaker Fuel Neutralizer Manual fire extinguisher material powder in bottle Web printout oO N Williams Pyro Inc Stovetop FireStop Hood installed magnet extinguisher No pressurized tank Web printout NST 615F Sensor Cooker Ceramic elec Hob w IR pop up cooking vessel T sensor Product Brochure Gas cooktops Gas cooktop w contact T sensor for pan bottom Product Brochure Gas cooktops Gas cooktop w contact T sensor for pan bottom Product Brochure P S E pon 3 D D siemens _ onimney nood wi smog sensor make nas racio contact bw eoker ahoo o Web printout 3 Si Chimney hood w smog sensor intake has radio contact btw cooker and hood Web printout siemens Mog General achure ot Siemans ont chen piadas Produc Brshut Siemens Hoods General brochure of Siemens entire kitchen appliances Product Brochure Solid disc heating element w temperature limiter Paper brochure 26 Gas cooktop RT L5500GFT Gas cooktop w contact T sensor for pan bottom afull Gas cooktop Gas cooktop w contact T sensor for pan bottom Product Brochure 4 5 6l 8 9 26 No Tite SSCS E E Company i Dato Using IR T sensor to measure external pot temperature ona gas KoonSeok Lee Sung Applications of Thermopile Infra red Sensor range Use to determine boiling point and boil dry condition
58. cooking fires All the technologies reviewed in detail have the potential to mitigate a significant percentage of surface cooking fires Their commercial feasibility varies by technology Detect and Extinguish Surface Cooking Fires Fusible Link or Temperature Sensor for Fire Detection There are commercially available systems that detect and extinguish surface cooking fires They currently do not meet all the industry requirements for technical feasibility because they are not configured to fail safe However the sensing and electronics necessary to detect the pressure in the extinguishing agent cylinders and to interconnect the system to the range is technically possible with a focused development effort There are some practical issues to resolve regarding high volume commercialization of this type of technology These systems are currently manufactured distributed installed and serviced through third parties to the appliance industry The appliance business and the fire extinguishing business are currently very different businesses with different requirements for installers and service personnel In order to commercialize a mass produced solution for the industry significant coordination could be required These systems are currently manufactured in volumes of a few to ten thousand units per year The technical manufacturing installation service and support infrastructure would need to be greatly expanded to provide products
59. cooking functions However the existing data did not reveal the cause of the increased cooking times In our meetings with appliance manufacturers they did not identify any existing data on cooking process temperature or the measurements of pan temperatures under various cooking conditions In order to evaluate the potential efficacy of a pre ignition threshold controller we needed to determine the pan temperatures required for a set of standard cooking procedures and compare these temperatures to the thresholds used to avoid a pre ignition condition In a limited number of focused tests in our labs at Arthur D Little we examined 1 the pan temperature associated with boiling searing and frying and 2 the control temperature thresholds of the two CPSC prototypes a Magic Chef gas range fitted with a prototype safety system and a Hotpoint electric range fitted with a different prototype safety system and a commercially available Japanese residential cooker made by Rinnai with the SAFULL pan temperature control function intended to prevent overcooking burning and overheating of deep frying oil We compared these temperatures to the pre ignition thresholds for oils identified in the literature e g the CPSC studies AHAM food test program edible oil data etc In a series of experiments using a variety of pan types stainless steel aluminum cast iron we measured the temperatures of the pan bottom and pan contents during various
60. cooking procedures Pan bottom temperatures were measured at the center and edge of the pan using K type thermocouples drilled into the base of the pan Pan contents temperature was measured using a third thermocouple placed into the liquid or pushed into the steak First we confirmed the range of temperatures at which cooking oil would ignite in our setup by heating oil on a burner with no safety system acting until ignition occurred The results were consistent with the significant body of data available on oil ignition temperatures The figure below shows the temperature ranges determined by us and those quoted by other sources The results of analysis and ignition tests of used oil are described in Appendix G 4 30 Oil fire point ee ery ranges ieee eee l i i Used oil l i i fire point wl T point ranges Temperature F Sugar fire point ranges ADL O O mf D n oO T 2 O Zz Bailey s Figure 4 23 Food ignition temperatures Sources Bailey s Industrial Oil and Fat Products Institute of Shortening and Edible Oils ISEO CPSC Study Phase III Report AHAM Food Fire Test Program ADL Tests Fire point Temperature at which spontaneous ignition can occur Flash point point at which external flame will cause ignition Next we investigated the different temperature regimes for a variety of cooking procedures We allowed different
61. cted Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Developed to be applicable for all cooktop systems Components system availability Most parts are available off the shelf or has been manufactured at high volume at low cost Installation No added effort than installing conventional range Serviceability Some training or new equipment is necessary for servicing the sensor PREVENT UNATTENDED COOKING WARNING ONLY MOTION POWER Effect on Cooking Process None nothing affected the burner operation Effect on Cooking Time None nothing affected the burner operation Effect of System on Consumer Behavior While Operating the Cooktop user need to read manual to learn that to stop alarm he she needs to be present near the cooktop Limits availability or efficacy of marketed cooktop features None Ease of System Verification User can verify easily if system is on or off by turning the heat source to high power level and leaving the room to see what happens Safety System Maintenance Cleaning the motion sensor surface is not more than wiping off the front sensor window cover which is part of the regular daily cooktop cleaning Power level sensor will most likely be located away from grease and food build up under the cooktop surface Cookware Applicability All cookware can be used with cooktop at any normal environment Range of Fire Incident Coverage Based o
62. ctivation Non contact T sensot Figure 4 21 Prevent Food Ignition in Pan No Signal Processing Mechanical actuation eesceseeeeeeeneeeeeeeees Figure 4 22 Prevent Boil Dry Spill Over T Sensor cee eeceeseeeseceeeeeeeeeeneeenneenes Figure 4 23 Food ignition temperatures eee esecsseceseceseeesseeceseceeeesneecsaeesseenees Figure 4 24 Temperature of pan contents during various cooking procedures Figure 4 25 Temperature of pan bottom at center of pan during various COOKING procedures 0 eee eee eeseceseeeneeceeeceeeeeeseetsaeenseenseee Figure 4 26 Differences between sensor readings and pan bottom amp contents temperatures sccis 28 sas sce cesses satteeadscecceas tive ee eevens Figure 4 27 Differences between sensor readings and pan bottom amp contents Figure 4 28 Trends in Cooking product mix 0 cc eeeeceeeeneecesececseeeeceeeeeceeeecseeeeneeeenas Figure 4 29 Technology Screening Results oeietess bocce teaces dst tip istl cede ceamectss lacs List of Tables Table 4 1 Fire Mitigation Technology Classes 1 Background Work has been sponsored over the past six years by the Consumer Product Safety Commission CPSC to study and develop technology to lessen the risk of surface cooking fires In the early phases of this work the CPSC used the resources of the National Institute of Standards and Technology NIST to determine if there were a common measura
63. determine cooking state 2 Auto detect for boil boil over boil dry T sensor for vessel bottom amp cooktop amp power level General Electric indica Temp signal plateu boil temp signal increase after plateau boil dry etc Company 3 Preventing boil over incidents by monitoring pan bottom temperature and usind a pre selected Matsushita Elec Ind decrease in temperature gradient as food boiling point Co Ltd 4 Cook modes warm simmer boil and regular Hi Med Lo settings available Compare realtime Arthur D Little Inc Tsensor acoustic sensor directly in contact w food The sensor sticks out of the back panel of the cooktop and its sensor tip is immersed in the cooking liquid A temperature sensor is attached at the end of a 2 bar link arm that can be ad justed to contact the cooking container The temperature sensor will convert the measured cooking vessel temperature into electrical signal that will signal alarm in cases of boil over or boil dry Moisture sensor above pot in hood on top of pot measure vapor and activate alarm audible visual and manipulate heat source when boiling is detected US 5079407 FIRE EXTINGUSIHING CONTAINMENT ALARM Whirpool USE TEMPERATURE SENSOR USE MOISTURE SENSOR 9A US 4773485 Pressurized extinguishing canister connected to valve networks within hood above stove Actuator are cables in tension connected w fusible parts Fire detection supp
64. dustries Installation Need additional tradesmen or technician to install Serviceability Need special equipment and staff expertise or licensing to perform servicing DETECT FIRE WARNING ONLY SMOKE SENSOR Effect on Cooking Process None can cook at any temperature Effect on Cooking Time Will negatively affect high temperature cooking with high particulate emission searing or frying since alarm most likely will turn on often and cause nuisance as cook needs to constantly reset turn it off during cooking time Effect of System on Consumer Behavior While Operating the Cooktop User will need to read manual to figure out that cooktop will sound alarm whenever excessive amount of smoke is produced increasingly during cooking Limits availability or efficacy of marketed cooktop features None Ease of System Verification Will need a service technician to verify sensor operation working at factory set level Safety System Maintenance User s maintenance might require specialist s help to clean the smoke sensor and make sure it is working at proper calibration level For new houses where smoke sensor power is connected to main electrical wiring any servicing will require specialist help Cookware Applicability All cookware can be used with cooktop at any normal environment Range of Fire Incident Coverage Based on existing fire data Probably will detect less than 40 of cooking fire incident since it will only warn user that there is exc
65. e e The degree of mitigation of fires addressed Will prevent cooking fire from occurring e Effect of Safety System on Cooktop Performance After Actuation of System None since it prevents any fire from occurring no extra cleaning or adjustment is necessary after each actuation e Effect of Actuation on the Safety System None system is always on during cooktop operation e Potential for False Actuation Potential for false negative if temperature sensor and cooktop did not have good contact due to surface dirt or misalignment e Can Operate Over product life w o failure safety factor of 2 Looks problematic no data Sensor is unprotected e Can operate within reasonably foreseeable misuse conditions durability Looks problematic but no data Sensor is out in the open and have high likelihood to be impacted by cooking wares e Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop might still work if safety system is off Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work for all models of one product type Components system availability Most parts are new parts that need to be developed and manufactured Installation No different than conventional range Serviceability Current staff needs some training and or new equipment to test service the sensor 12 13
66. e Operating the Cooktop None Limits availability or efficacy of marketed cooktop features None Ease of System Verification Not Applicable Safety System Maintenance None regular cooktop maintenance only is needed Cookware Applicability Work for all types of cookware Range of Fire Incident Coverage Based on existing fire data Not Applicable Percent of new product sales covered by this technology Not Applicable The degree of mitigation of fires addressed Not Applicable Effect of Safety System on Cooktop Performance After Actuation of System Cooktop will be burned down Effect of Actuation on the Safety System Not Applicable Potential for False Actuation Not applicable since fire will never be detected Can Operate Over product life w o failure safety factor of 2 No additional part installed that might have any effect to current cooktop product life Can operate within reasonably foreseeable misuse conditions durability No additional part installed that might have any effect to current cooktop durability Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down No additional part installed that might have any effect to current cooktop safety standards Safety system components might pose added risk to consumer No additional part installed that might pose added risk Applicability across product types and product models No additional part installed
67. e a significantly higher temperature than normal cooking condition needs to be detected by the temperature sensor for the system to actuates Can Operate Over product life w o failure safety factor of 2 Looks good but no data Can operate within reasonably foreseeable misuse conditions durability Looks good since it will be out of the way of the user during normal cooking operation but no data Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop will still be operable despite the safety system is not on operating Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work for all models for one product type but need other approach on island installation or others where there is no wall or hood space to locate the sensor alarm Components system availability Need to be adapted from other industries Installation Need additional tradesmen to install the alarm and heat sensor Serviceability Specialized equipment and or staff expertise or licensing is necessary DETECT FIRE WARNING ONLY OPTICAL T SENSOR Effect on Cooking Process None safety system only actuates when a fire had already occurred Effect on Cooking Time None safety system only actuates when a fire had already occurred Effect of System on Consumer Behavior While Operating the Cooktop None Limits av
68. e for daily cleaning Compagnie Europeenne Pour Equipment Menager Only work for induction type cooking hob very small in market 6 JP 9056601 7 JP 4006325 Tsensor at suction passage below burner through its circumference and in smoke duct below burner system When abnormal heat is detected alarm turns on and gas valve is turned off An energy Temp sensor is installed within a downdraft duct behind burner When food overheat oil The energy sensor detected pre set radiation energy from cooktop turn off burner and stop blower Yamaoka Kinzoku Kogyo KK Detection threshold might easily be compromised dirt boil over Matsushita Electric Ind Corp Sensor easily soiled by grease amp not accessible for daily cleaning 8 JP 7171061 9 US 5608378 T sensor is directly inserted to pan pot content T sensor is attached to an alarm system that can generate synthesized voice to alert cooker of cooking fire danger when Tfood oil Tthres eg 200 C Power level elec or flame gas sensors If sensor detect heat source is on a warning indicator located next to exit door audible alarm turns on when door is opened prevent unattended accidental on User have to install uninstall sensor everytime used nuisance None Does not seem to be very effective High likelyhood of false alarms 10 US 5942816 11 12 US 3781506 13 JP 5018539 Modified fuse for electric cooktop with build in tim
69. e it will actuate whenever fire is detected Percent of new product sales covered by this technology Less than 90 since downdraft installation or island installation does not require or cannot have hood installed The degree of mitigation of fires addressed Extinguish or manage a fire Effect of Safety System on Cooktop Performance After Actuation of System Cooktop will need significant cleaning and adjustment since fire has occurred and extinguisher material has been released Effect of Actuation on the Safety System Service call or component replacement recharging fire extinguisher material is necessary to return system to its ready state Potential for False Actuation None a significantly high temperature more than normal cooking condition is needed to melt the fusible parts Can operate over product life w o failure safety factor of 2 Looks good but no data Similar applications has been implemented for sometime in commercial kitchen Can operate within reasonably foreseeable misuse conditions durability Looks good but no data System is out of reach of user during normal cooking operation Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop will still able to work even though safety system is not on operating Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can
70. e of System Verification Verification of operation needs the help of service technician Safety System Maintenance Need to clean temperature sensors from cooking soil grease build up Cookware Applicability Works for all types of cookware at any normal environment Range of Fire Incident Coverage Based on existing fire data Will detect more than 90 of cooking fire incidents since it will actuate whenever a fire is occuring Percent of new product sales covered by this technology Will cover less than 90 of new product sales since non hood installations downdraft and island cooktop need different approach The degree of mitigation of fires addressed Will only warn of the presence of cooking fire Effect of Safety System on Cooktop Performance After Actuation of System Since there is high probability that fire has commenced when the system is triggered the cooktop can be damaged from the high heat due to no provision to quickly extinguish the fire once it is detected Even if the user act quickly and extinguish the flame w a portable fire extinguisher clean up might be necessary Effect of Actuation on the Safety System User might have to reset the alarm once the fire has been controled Since there is high probability that fire has commenced when the system is triggered the sensor can be damaged from the high heat due to no provision to quickly extinguish the fire once it is detected Potential for False Actuation No chance of false alarm sinc
71. e periods for auto power off is determined by heat source power levels When no switching operation is performed by user during pre set period since the last time a switching operation is carried on during the on times of heating element burner turns off to prevent user from forgetting to turn off cooktop after use The cooking appliance automatically turns off the heater a predetermined time after a last pressed switch i e automatic power off function A caution lamp indicates that the heater will automatically be turned off a minute prior to the automatic power off function None Toshiba Corp Matsushita Electric Ind Corp TIMER AND POWER LEVEL TIMER ONLY JP 61038338 JP 4093529 The IR smoke detector will detect a threshold amount of smoke then set a timer on After a pre set time eg 10min has elapsed from the timer check again if smoke generation increase not reducing shut off valve if not reset timer and repeat procedure A photoelectric sensor light projector and receiver is installed in downdraft cooking vent hood When smoke level in the vent is gt pre set value sensor will send signal to turn on alarm and turn off heater NIPPON DENSO CO LTD Matsushita Electric Ind Corp SMOKE SENSOR US 5611327 Smart range w multiple sensors amp functions For fire safety of cooktop a nearness sensor check for authorized user and or utensils If unauthorized person utensil is around used bur ner is lock
72. ead manual Limits availability or efficacy of marketed cooktop features None Ease of System Verification Need special equipment or specialist s help to determine systems operability Safety System Maintenance Need additional procedure to clean the temperature sensor from grease or food soil build up Cookware Applicability Some cookware materials or shape can compromise safety system performance e g glass ceramic ware cookware with concave bottom Range of Fire Incident Coverage Based on existing fire data Likely will address more than 40 of fire incident since it prevents pre ignition condition from occurring during most of the cooking processes 18 Percent of new product sales covered by this technology Multiple designs applicable for gas and solid or coil electric elemet cooktops Has some design for smooth top Ceran gold alloy track but the application might be more difficult for a reliable means to gauge pot content temperature The degree of mitigation of fires addressed Will prevent fire from occurring Effect of Safety System on Cooktop Performance After Actuation of System None no adjustment or cleanup necessary after safety system actuation since it prevents fire from ever occurring Effect of Actuation on the Safety System Since cooktop will continuously manipulate heat to keep foodstuff at proper temperature no reset is necessary after each actuation Potential for False Actuation Potential for false negative if te
73. earby The user would need to actuate a re set button on a regular basis 4 49 Potential Effectiveness of Technology to Mitigate Cooking Fires If all the unattended cooking fires could have been avoided by having a user attend to the range these technologies would eliminate between 65 and 70 of all surface cooking fires Unlike a fire extinguishing approach these systems are intended to prevent a fire from starting The fire would be avoided rather than extinguished In the systems defined by the body of patents the operation of the safety system can be verified manually but not automatically The technology would fail safe because the range would not operate without the circuit in place and operating It is possible that an electro mechanical implementation could be designed 1 e no electronic control board required However with electronics a self check could potentially be built into the system This system is unlikely to be tricked or result in false actuation Development Needs and Issues As with the motion detector systems the primary development need for this technology would be to obtain some consumer feedback on the acceptability of the general approach This technology would be implemented to change consumer behavior It is important to understand how consumers would respond to this requirement Technically the approach would be straightforward to implement 4 7 4 Prevent food ignition in the pan electric
74. ed for authorization transmitter has to be carried by person embedded in utensils The pot support grid has a weight measuring device If no weight is sensed then burner turns off Timer is used for individual burner to turn it off automatically Have bypass functions for when pot is temporarily lifted or pot is left on grid after finishing w cooking lock burner off None US 5608378 JP 5018539 Power level elec or flame gas sensors If sensor detect heat source is on a warning indicator located next to exit door audible alarm turns on when door is opened prevent unattended accidental on An odor sensor is used to determine what kind of food is cooked and also to determine if food is over heating It is connected to controller that can manipulate heat source None Sharp Corp JP 5018539 JP 8086445 Auto detect of food type using odor sensor Use food type info for auto cooking and use odor data to determine food fire and manipulate burner shut off when that happens A contact touch sensor combined with Tpan bottom sensor is used to determine if pan pot is on top of burner When pan is not on burner burner flame is either reduced or off so no cloth sleeve catch fire Sharp Corp Tokyo Gas Co Ltd JP 9056601 Tsensor at suction passage below burner through its circumference and in smoke duct below burner system When abnormal heat is detected alarm turns on and gas valve is turned off Yamaoka
75. ed into a countertop Any of these product classes can be constructed in a downdraft configuration meaning that a ventilation system is integral to the cooking product and no hood would be required installed Gas units are further divided into the following product categories e Open Burners e With pilot e Electronic Ignition e Sealed Burners Electric units are further divided into the following product categories e Smoothtop glass ceramic e Open coil In our analysis we needed sales numbers in percentages associated with the following product categories We have made estimates of these numbers based on AHAM data and information provided to us by manufacturers Overall sales percentages and trends are shown in the following graph 4 37 50 45 40 35 30 25 Percent of total sales 20 15 10 1995 1996 1997 1998 1999 2000 2001 Figure 4 28 Trends in cooking product mix e Percentage of products overall that currently have an electric connection gt 90 e Percentage of surface cooking products that are installed in an island or peninsula configuration that would inhibit or make more complex the installation of an overhead hood lt 10 e Percentage of surface cooking products with downdraft ventilation lt 10 4 5 Technology Screen We evaluated each Technology Class listed in Section 4 2 in accordance with the Screening Criteria listed in Section 4 3 In the scoring process a numer
76. ed on existing fire data Will address between 40 90 of the cooking fire incidents due to the fact that this system currently not applicable for gas ranges Percent of new product sales covered by this technology Less than 90 It will not work for gas cooktop since heat from burner will be mistaken as cooking fire probably the same with radiating electric heat element The degree of mitigation of fires addressed Will extinguish or contain fire Effect of Safety System on Cooktop Performance After Actuation of System Since fire has occurred and system will release fire extinguisher on cooktop surface significant cleaning and adjustement will be necessary to operate cooktop again Effect of Actuation on the Safety System User will need to recharge refill the fire extinguisher before it can operate again Potential for False Actuation Potential for false positive when sensor is not properly cleaned and might miss a fire incident Potential for false negative when optical sensors which are not part of daily cooktop clean up are not properly cleaned and is obstructed by airborne food or grease particles Can Operate Over product life w o failure safety factor of 2 Looks problematic but no data Sensor optical window which are not part of daily cooktop clean up can easily get covered up with airborne cooking oils particles and needs calibration Extinguisher needs to be recharged Can operate within reasonably foreseeable misuse conditions d
77. el diameter surface configuration heat conductor w current measurement A conductive thin plate is formed of copper foil printed in the thermoplastic resin film polyester fil a notch is installed in copper foil When flame is directly brought into contact with the thermoplastic resin film the thermoplastic resin film is contracted part of the notch in copper foil breaks and it does not conduct A combined ultrasonic microwave doppler sensor is developed for a sensitive and fast fire alarm that is robust against false alarm A new micro machined relative humidity sensor was developed Output signal is linearly proportional to relative humidity from 0 100 RH Claims low cost and reliable sensor can be applied to cooking ranges of different types electrics and gas Compagnie Europeenne Pour Siemens AG Institut fur Instrumentelle Analytik Hermann CONTACT TEMPERATURE SENSOR FOR COOKING VESSEL NON CONTACT TEMPERATURE SENSOR FOR COOKING VESSEL FLAME FIRE SENSOR FLAME FIRE SENSOR HUMIDITY SENSOR Conference pape Automated Cooking and Frying control using a gas sensor microarray A discussion on a new development effort on a gas sensor microarray that is specifically to determine the doneness level of steak cooking The sensor is located on the underside of the pan lid Institut fur Instrumentelle Analytik GAS ODOR SENSOR Appendix B Technologies Eliminated in Initial Screen
78. ements of the discussions at these meetings are confidential as per our agreement with AHAM and CPSC but we have incorporated the general information into our evaluations In addition to the literature reviews and meetings we conducted some tests in our lab to obtain additional data on system performance and characteristics We obtained the CPSC range prototypes and conducted limited testing on both the gas and electric units We reviewed the Good Housekeeping report covering their tests of these units We obtained a Rinnai Gas Table with a temperature controller and conducted numerous tests to understand its operation and performance To supplement these tests we reviewed the Rinnai User Manual translated from Japanese by AHAM Finally we utilized our understanding of the appliance industry the standards process the science of cooking products and the product development process to support our analyses and evaluation work 3 4 Develop Evaluation Criteria Specific evaluation criteria and metrics were developed in the categories of cooking performance operability reliability durability manufacturability installation service safety and effectiveness in addressing surface cooking fires These criteria and metrics were reviewed with representatives from CPSC and AHAM It was agreed that as a starting point for the screening work each criteria would have equal weighting relative to each other These criteria were further grouped into two
79. er Each heat element ctrl knob has 1 fuse The modified fuse will turn off heat element to reset after a pre determined period of time pre set or user selected Non contact T sensor for cooking vessel specifically for induction electric cooktop Auto detect of food type using odor sensor Use food type info for auto cooking and use odor data to determine food fire and manipulate burner shut off when that happens Timer period selection is arbritrary or dependent on user not desireable to let user define safety limits US 4577181 A contact sensor for electric heater to detect pan pot presence above heater Fissler GmbH Only address fires from non food mat l detailed sensor drawing Germany small of cooktop fire source Not many induction cooktop in the market today Find patent s figure later and realize it is for oven General Electric Co Schenectady Sharp Corp 14 US 4483314 Pull out blanket from drawer underneath the burner heat source Used to manually smother fire None User has to manually smother fire harmful 15 JP 10201871 16 17 18 JP 9206393 19 JP 11221297 Manual fire extinguishing sheet Fire extingusih agent is suspended in a flexible amp fusible encasing from polyethylene film When fire occurs drape sheet on stove to melt film and delivers extinguisher Kitchen mat with incombustible material to smother fire manually Extinguish stove fire and prevent fire from expanding in
80. erature higher than the actual pan bottom temperature the controller would cause the element or burner to modulate prematurely thus increasing cooking time or affecting a cooking process There is much work that would need to be done to develop a reliable and durable pan contact sensor that has the performance characteristics needed for a controller that does not impact cooking time or cooking quality The effectiveness of the system depends on good contact between the pot and the sensor Pan type and quality will affect the accuracy of the pan bottom temperature measurement We anticipate that a system could be made to be compatible with most pan types However we expect that cooking times for glass or ceramic cookware could be extended because of the larger thermal gradient in those materials Reliability and life are significant issues The gas tables with spring loaded temperature sensors have been selling in Japan for 10 years Two companies provided general data on sensor life Rinnai has indicated that the average life of the sensors is expected to be five years The also indicated that the product improvement cycle is short and the manufacturer keeps spare parts in stock for about five years Paloma informed us that the average life of the sensor is expected to be eight years 4 51 This life would probably not be acceptable to the US market that expects 15 20 year life from range components Designing a pan contact sensor that can mee
81. ersion has an electric cut off switch that cuts the power the the electric stove Claim that user can adjust sensor s sensitivity photo conductive cell Preliminary stage Detection of critical level smoke alarm prior to combustion photo electric Then audible alarm if not reset by user after time delay eg 45 sec gas supply to appliance cuts off Else combo of smoke and T level will disconnect power supply immediately If flame occurs immediate power disconnect amp provision of auxiliary output extinguisher on or contact outside services 911 etc DAIKIN KOGYO KK Cabinova Sweden Technology Research Corporation JP 4093529 JP 2182274 A photoelectric sensor light projector and receiver is installed in downdraft cooking vent hood When smoke level in the vent is gt pre set value sensor will send signal to turn on alarm and turn off heater Range hood act as a fire enclosure containment unit Tsensor detect ambient T around cook table then activate a buzzer and then drops down to cover entire surface cooking unit automatically activated with sensors to detect fire and activate release Matsushita Electric Ind Corp None USE OPTICAL TEMPE RATURE OR FIRE SENSOR USE SMOKE SENSORS FIRE CONTAINMENT NO EXTINGUISHER AGENT JP 11221297 Extinguish stove fire and prevent fire from expanding into hood duct Nozzle that sprays water droplet is situated inside the duct of a range hood to spray into duct
82. essive smoke generated during cooking And there is a danger of user being desensitized to the noise if smoke alarm produced too many false alarms during high heat cooking Percent of new product sales covered by this technology More than 90 sensor can be located near any type of cooktop The degree of mitigation of fires addressed It will warn that a possible fire is about to happen Effect of Safety System on Cooktop Performance After Actuation of System None as long as user is around to take preventive measure and stop the fire from actually occurring Effect of Actuation on the Safety System User needs to manually reset the alarm to off when he she has addressed the source of the smoke Most likely alarm will turn on much earlier before a fire actualy occurred Therefore if addressed promptly no damage should be done on the sensor or alarm Potential for False Actuation False positive smoke detector will turn on although no pre ignition condition is present during searing or frying Can Operate Over product life w o failure safety factor of 2 Looks problematic but no data sensor might get soiled and covered up by airborne cooking or grease particles Can operate within reasonably foreseeable misuse conditions durability Looks problematic but no data sensor might get soiled and covered up by airborne cooking or grease particles Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fa
83. etermine conclusively whether the technologies could pass the defined tests However the group s guidelines for the requirements of any technology are listed below Not all the requirements are pertinent to all the potential fire mitigation technologies Reliability is clearly an important open item that would need to be addressed directly as part of a product development process for any new safety system Perform as designed for twice its design life It is recommended for safety components to have minimum of 100 000 cycles Control components removed and installed 2 000 times without need for re calibration based on one disassembly operation for cleaning per week for 20 years with a 2x safety factor applied A burner needs to be cleaned thoroughly w washcloths and standard household cleaners for a total of 15 000 cycles based on one cleaning per day over 20 years with 2x safety factor Control components shall perform as designed after dragging 12 diameter cast iron with heavy pattern ribbed surface The pan is assumed to be drawn across burner with a horizontal motion of 4 6 inches for a minimum of 50 000 times This corresponds to pan movement for 2 3 times per day for 20 years with 2x safety factor If a sensor is attached to a heating element where disassembly is allowed for cleaning it should be removed and installed 2 000 times and reseated using 12 cast iron pan with a downward force not impact of TBD Ibs Perfo
84. f surface cooking fires There has been some discussion about the statistics that indicate that cooking materials are an ignition factor in 72 77 of surface cooking fires The question was posed whether the cooking materials that ignite are potentially outside of the pot i e in the burner well or in the cooktop rough in box It has been hypothesized that a safety system that controlled pan temperature would not affect the ignition of oil or grease that had accumulated around and in the cooktop itself We conducted some very preliminary tests to investigate this hypothesis We measured cooktop temperatures around the burner bowl rough in box and cooktop surface during standard cooking functions and during conditions in which pan contents reached pre ignition temperatures We did not find any cooktop surface temperatures in the burner bowl under the burner in the rough in box etc that neared flash point of oils when the pan was at pre ignition temperatures We strongly agree that grease and oil around the cooktop would exacerbate a fire This approach is potentially applicable to gas units and open coil electric units The Japanese units that use a pan contact sensor are generally open burners with a hole in the 4 52 center of the burner for the sensor Obviously a different configuration would be needed for a sealed gas burner The implementation of this control approach in electric smoothtops is not currently feasible The temperature
85. following seven specific tasks 3 1 Identify Patents Products Technologies Systems and Concepts We cast a broad net to identify the products technologies systems and concepts that have the potential to address surface cooking fires Some of these technologies were available in the public domain from the patent database web sites technical literature conference proceedings and product brochures In addition we followed the inventor trail from CPSC meeting and phone logs AHAM files Arthur D Little files and meetings with appliance manufacturers Some concepts particularly as they related to combinations of sensor technologies in control systems were proposed at Arthur D Little as part of the searching and technology classification process 3 2 Structure Patents Products into Technology Classes In order to evaluate the feasibility of fire mitigation approaches we structured the patents products concepts technologies and systems into 22 technology classes Both CPSC and AHAM reviewed these technology classes prior to our initiating the evaluation work A number of the products systems or concepts that were grouped into these technology categories constituted a complete approach to address surface cooking fires Other patents or technologies could potentially be part of an approach that would address surface cooking fires for example a sensor technology or an extinguishing agent or a contact temperature sensor In
86. for the entire range market Prevent Unattended Cooking Warning and Control Motion Sensors This technology is very early in the development process At this stage however the general approach appears to be technically feasible The reliability and life of the motion sensors and electronics would need to be addressed A power level sensor for a gas burner would need to be developed It is expected however that a focused two year development effort could produce a manufacturable product The practical aspects of this solution however are not so straight forward This approach requires significant changes to consumer behavior It is not clear that the requirements imposed by the systems as described would be acceptable to consumers The system that couples a motion sensor with a power level sensor may mitigate some of the consumer resistance It would be critical to conduct some consumer feedback work to understand their response The safe cooking products will enter the market only if consumers purchase them the products must be acceptable to the consumers 4 55 Prevent Unattended Cooking Warning and Control Power Level Sensor and Timer The feasibility of this approach is very similar to the motion sensor systems The approach is technically feasible and could be manufactured using conventional techniques The consumer response to the approach needs to be tested Prevent Food Ignition in the Pan Contact Temperature Sensor
87. g Tests D1 Temperature F 1000 800 600 400 200 100m Water Test in Stainless Steel Pan on CPSC Gas Range CPSC TC 200 PC pan contents Boil dry 480s 400 600 PBC pan bottom center 800 Time s PBE pan bottom edge 1000 1200 1400 CPSC TC built in thermocouple 1600 D2 Temperature F 100m Water Boil Test in Stainless Steel Pan on CPSC Electric Range 200 PC pan contents water temp lt 212F boiling not reached 400 600 PBC pan bottom center 800 Time s PBE pan bottom edge 1000 1200 1400 TC1 TC2 and TC3 built in thermocouples 1600 D3 Temperature F 1000 800 600 400 200 100m Water Boil Test in Stainless Steel Pan on Rinnai Range burner shutdown 200 boil dry 400 600 800 1000 1200 Time s PC pan contents PBC pan bottom center PBE pan bottom edge 1400 1600 D4 Temperature F 1000 800 600 400 200 100ml Oil Test in Stainless Steel Pan on CPSC Gas Range CPSC TC 200 PC pan contents 400 600 PBC pan bottom center 800 1000 Time s PBE pan bottom edge 1200 1400 CPSC TC built in thermocouple 1600 Temperature F D5 1000 800 600 400 200 100ml Oil Test in Aluminum Pan on CPSC Gas Range CPSC TC 200 PC pan contents 400 600 PBC pan bottom ce
88. g steak were adversely affected In addition the sensors could be easily damaged The problem with the prototype is that the temperature sensors appear to be sensing as much of the element temperature as the pan temperature In both cases the algorithm used was in principle valid for the task although this would need to be confirmed for all cooking functions However extensive testing would be required to ensure that the exact parameters chosen temperature thresholds cycling times reduced heat input rates etc were suitable for the widest range of cooktops pan types and cooking functions In sum the sensor design would have to be improved significantly so that the pan bottom temperature measurements were more accurate and the sensor was much more robust Some self check or self calibration could be needed to implement a fail safe system Given the product development cycles in the industry this effort probably would require a minimum of 2 3 years of development time and significant investment by both the appliance manufacturers and their vendors 4 53 If this were successful the resulting system would have a high probability of preventing most surface cooking fires without requiring modification of consumer behavior or affecting cooktop function 4 54 4 8 Results Summary This section summarizes our evaluation regarding the technical practical and manufacturing feasibility of the selected technologies to address surface
89. high temperature cooking searing Effect on Cooking Time Likely to affect cooking time by less than 10 Effect of System on Consumer Behavior While Operating the Cooktop User need to read the manual to use the new mode selecting control knob or buttons without the need to read manual Limits availability or efficacy of marketed cooktop features None Ease of System Verification Need special equipment or specialist s help to determine systems operability Safety System Maintenance Need additional procedure to clean the temperature sensor from grease or food soil build up Cookware Applicability Need special cookware for system to work properly Known emissivity Range of Fire Incident Coverage Based on existing fire data Likely will address more than 40 of fire incident since it prevents pre ignition condition from occurring for most of the cooking process Percent of new product sales covered by this technology Can be installed to any new cooktop though more work needs to be done for the gas fired cooktop to make sure that radiation from flame will not be mistaken as pot high temperature The degree of mitigation of fires addressed Prevent fire from even occurring Effect of Safety System on Cooktop Performance After Actuation of System None fire should never even occur Effect of Actuation on the Safety System None no cleaning or adjustment is necessary every time safety system actuates Potential for False Actuation Potential for fa
90. hure PEMALL 21st Century Int l Fire Equipment amp Services Twenty First Century 10 JP 8107942 Nozzles connected to pressurized water source capable of delivering fine water mist fog to suffocate and cool fire stove Using fusible parts to activate nozzles NOHMI BOSAI LTD 11 Fire Line Hood installed extinguisher using fusible link Ansul Fire Suppression 12 Firemelt hood Hood installed extinguisher using fusible parts and a new powder extinguisher that suppse to work well with grease fire too USING FUSIBLE PARTS AS DETECTOR AND ACTUATOR 13 JUS 3653443 Thermostat in hood detect fire Circuit connected to thermo activate removable fluid extinguisher tank in hood and cuts off electric gas valve to range and turns on alarm Mon Are Inc 14 US 5351760 T sensor 1st temp threshold fan turns on 2nd temp threshold alarm turns on 3rd temp threshold range shuts off beyond 3rd temp threshold fusible link melt and dispense None 15 JUS 5868205 Fire extinguishing agent container above the cook range at the back of the range hood w a bimetal actuating device Actuated when ambient temp reached certain temp Fail Safe Safety Systems Inc 16 US 6029751 TC or metallic alloy element responds to high threshold T It sends signals to release fire suppressor amp turns alarm on amp turns off electrical gas supply When Tsensor cools off suppressor valve auto closes
91. ial this technology utilizes a non optical temperature sensor such as a thermocouple diode or thermistor located near the cooktop usually in hood to detect fire When the sensor response exceeds a threshold temperature a release mechanism for the fire extinguishing agent is actuated As with the system described previously a heat source cut off mechanism or an alarm can be included in the system BxTNquich T gt THrestor gt Figure 4 2 Detect Extinguish Fire Non optical T sensor 4 4 Detect Extinguish Fire Optical Temperature Sensor Tech Class 3 In this fire extinguishing technology an optical temperature sensor such as an infra red IR sensor is used to monitor the temperature surrounding or on top of the cooktop When a temperature is sensed that exceeds a threshold an alarm is sounded At the same time the system will actuate the release of the fire extinguishing agent and can also turn off the cooktop heat source e P Ht SPRAY NOZZLE yy TEMP l l 1 1 l I TIME eeTinquish T gt THELD Figure 4 3 Detect Extinguish Fire Optical T sensor Detect Extinguish Fire Smoke Temperature Sensor Tech Class 4 This fire extinguishing system utilizes the combination of both smoke and temperature sensors to determine the presence of a surface cooking fire First the smoke sensor will detect a significant amount of smoke and
92. ial especially cooking fires w breakdown of specific causes and types of Linda Smith Study cooking equipments involved CPSC Editorial comments of the first draft for the final report on the Study of Response to Peer Reviewers Comments on Tech for Detecting Pre ignition Conditions of Cooking Related Fires Andrew Trotta 7 Range Fires Project Technical Reports Assoc w Elec Ranges CPSC Prepared By Prepared For Defining sources of cooking fire Define potential solutions 1_ Nov 1998 Working Group Meeting Minutes review previous TC devices Wayne Morris Cooking Fires Issues Task Group Task group reviewed AHAM s Recipe for Safer Cooking Campaign Discuss other non technical solution for cooking fire prevention how to increase public awareness on cooking fire and how can building codes be improved to address Working Group on Careless 2 _ Feb 1999 Task Group 4 on Non Technological Options cooking fire incidents sprinkler systems Wayne Morris Cooking Fire Range manufacturers agree TC pan feedback mech Shows greatest promise for solution Discuss cooking test result on CPSC elec prototype Discuss predicted system cost Discuss other solutions from industry Cherry TRC Wayne Morris Cooking Fires Issues Task Group Cooking fires joint task group are determining the types of 4 Aug 2000 Work Assignments for Task Group pass in order for it to be a viable technological option Wayne Morris Cooking Fires Joint Task Group Review of residential
93. icability across product types and product models Will need more development to apply for gas cooktop specifically for the power level sensor No patent found that specifically address this type of technology on gas cooktop although it does not seem difficult to do Components system availability Most components are off the shelves or have been manufactured at high volume and low cost Installation No added effort than installing range Serviceability Some training or new equipment is necessary for servicing the sensor PREVENT UNATTENDED COOKING WARNING ONLY MOTION SENSOR ONLY Effect on Cooking Process None nothing affected the burner operation Effect on Cooking Time None nothing affected the burner operation Effect of System on Consumer Behavior While Operating the Cooktop user need to read manual to learn that to stop alarm he she needs to be present near the cooktop even during simmer cooking Limits availability or efficacy of marketed cooktop features None Ease of System Verification User can verify easily if system is on or off by turning the burner and leaving the room and see what happens Safety System Maintenance Cleaning the motion sensor surface is not more than wiping off the front casing cover which is part of the regular daily cooktop cleaning Cookware Applicability Any utensil at any environment will work Range of Fire Incident Coverage Based on existing fire data Probably will catch less than 40 of c
94. ical score of 9 corresponded to a High score 5 corresponded to a Medium score and 1 corresponded with a Low score The scores of each technology are detailed in Appendix E The basis of each score is detailed in Appendix F A graphical representation of the results of this screening process is shown in Figure 4 29 The technology scores are plotted on the axes of Impact on Product Value and Effectiveness in Mitigating Surface Cooking Fires A technology that is relatively more effective in mitigating surface cooking fires with limited impact on other aspects of the product value would be plotted in the upper right hand corner of the graph 4 38 This screening process was effective in providing a comparison among a set of very different technologies It helped to highlight a subset of technologies for further consideration 140 Least Impact 120 More Desireable 11 19 20 Region 100 o 80 gt T gt 5 60 17 18 21 2 E 40 Less Desireable 20 Region Most Impact 0 Least Most Effective lt Effectiveness in Mitigating Surface Cooking Fires gt Effective Figure 4 29 Technology Screening Results The technologies that are clustered in the upper right hand corner of the graph are listed below 1 Detect and Extinguish Fire Fusible Link for Fire Detection Tech Class 1 This technology scores relatively highly because it has minimal effect on consumer behavior cooking performance o
95. icant issue with the technology is that in its current configuration it cannot guarantee fail safe operation as defined by the industry as inhibiting cooking function on the range if the safety system is not operating properly There is no interconnect to ensure that the range is shut down if the pressure in the cylinders drops below a set level or if the extinguishing cylinder is not refilled There is a pressure gauge on the cylinder to determine if the cylinder is operational The electronics that control the system also have a self diagnostic function that will flash an LED to let the user know that the system is operating correctly The homeowner is responsible for checking the pressure in the cylinders and having the units hydrostatically tested at appropriate intervals recommended by the manufacturer for every 12 years Some fire extinguishing manufacturers mail reminder cards to the homeowners at the appropriate intervals to have the systems checked This approach has its limitations With regard to impact of the fire extinguishing system on the cooktop or on the safety system after actuation these technologies are messy to clean up The fire extinguishing material goes all over the room and there is significant effort required to recharge the system Development Needs and Issues The primary development need for this technology is a means to ensure fail safe operation This would mean that it would need to have some way to confi
96. il safe cooking system shut down Cooktop will continue on working if smoke sensor is not operating Safety system components might pose added risk to consumer None Applicability across product types and product models Will work for all models Components system availability All parts are on the shelves parts Installation Needs additional tradesmen to install especially for new houses where power source of alarm is from the main electric line Serviceability Needs additional tradesmen to service especially for new houses where power source of alarm is from the main electric line CONTAIN MANAGE FIRE PASSIVE THREE SIDE WALLED COOKTOP Effect on Cooking Process None Effect on Cooking Time None Effect of System on Consumer Behavior While Operating the Cooktop Have to always adjust pot handle a certain way Access to heat source on the back is limited cannot use it for active cooking where user needs to constantly manipulate the foodstuff in the vessel Limits availability or efficacy of marketed cooktop features Yes cannot smoothly transfer foodstuff or cooking vessel from surrounding tabletop to the cooktop or vice versa e g during deep frying Almost impossible to use the back burners when the front ones are also used Ease of System Verification Nothing to verify it is just a permanently mounted fire resistant wall Safety System Maintenance Only needs to clean extra surface of the three side walls Cookware Applicabil
97. ill actuates and resets automatically e Potential for False Actuation Potential for false negative if temperature sensor and cooktop did not have good contact due to surface dirt or misalignment e Can Operate Over product life w o failure safety factor of 2 Looks problematic no data Sensor is unprotected e Can operate within reasonably foreseeable misuse conditions durability Looks problematic but no data Sensor is out in the open and have high likelihood to be impacted by cooking wares e Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop will still work even though the safety system is not on operating Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work for all models of one product type Components system availability Most parts are new parts that need to be developed and manufactured Installation No different than conventional range Serviceability Current staff needs some training and or new equipment to test service the sensor PREVENT FOOD IGNITION IN PAN ELEC SIGNAL PROCESSING AUTO ACTIVATION NON CONTACT T SENSOR e Effect on Cooking Process Will affect quality on high temperature cooking such as searing e Effect on Cooking Time Might affect cooking time by less than 10 e Effect of System on Consumer Behavior While Operating the Cook
98. ity High Is robust durability data available conducted Medium Looks good but no data Low Looks problematic but no data 4 26 4 Safety Safety system components might pose added risk to consumer High Medium Low None Some but easily and obviously modifiable Some and not easily or obviously modifiable 5 Manufacturability Installation Service Applicability across product types and product models High Medium Low Developed to be applicable to all cooktop systems Can work for all models of one product type e g sealed burners open burner open coil glass ceramic gas pilot downdraft systems May require different design for functionally different models within a product type Components system availability High Medium Low Installation High Medium Low Serviceability High Medium Low All parts are on the shelf parts or have been manufactured for high volume low cost applications Most parts are available on the shelf or have been manufactured in high volume at low cost Most parts are new parts that need to be developed and manufactured or adapted from other industries No added effort than installing range More time but no added people to install Additional tradesmen and or technicians required for installation Current staff can conduct routine maintenance with existing equipmen
99. ity cannot use larger cooking vessels or those with long handles Range of Fire Incident Coverage Based on existing fire data Not applicable since system only contain fire to the back and sides of the cooktop but does not contain the top or front side If left continued unextinguished by user fire will eventually spread throughout the kitchen Percent of new product sales covered by this technology Almost everything except island versions The degree of mitigation of fires addressed Not applicable does not warn prevent extinguish or contain fire continuously Effect of Safety System on Cooktop Performance After Actuation of System Not applicable since if fire did occur and user did not extinguish it manually cooktop will continue to burn and fire will spread Effect of Actuation on the Safety System Fire resistant wall surface will just need some cleaning though the rest of the cooktop kitchen can be ruined by fire Potential for False Actuation None nothing actuates Can Operate Over product life w o failure safety factor of 2 Side walls will have the same product life as the rest of the cooktop even longer Can operate within reasonably foreseeable misuse conditions durability Side walls most likely are made from a strong fire resistant material that can endure reasonably foreseeable misuse conditions Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut do
100. k of an attending person results in an alarm followed by power modulation or shut off if no one returns Technology Class 12 uses a power level sensor in addition to a motion sensor so that the system is activated only if the heat input to the hobs is above a threshold level The final Technology Class 14 is a warning system only An alarm will sound if no one is detected near an operating range but there is no control system to affect the power level These technologies are intended to work by changing consumer behavior They will encourage or require the cook to be present near the range during the cooking process In a way this approach is similar to the way the automotive industry encourages the use of seatbelts If we turn on a car and have not fastened our seat belt a warning will sound The warning bell is a reminder to follow safe behavior These technologies are either exactly analogous to this approach Tech Class 10 Warning Only or they continue one further step With the Warning and Control options the power input to the range is either modulated or shut off if the cook does not return to the range These technologies score highly in safety system effectiveness because they are intended to prevent a fire from igniting are applicable to most product classes and can be made to be fail safe The basic operating assumption is that if a cook is attending the range then the significant number of fires that are associated with unatte
101. l Fire Protection Association April 2000 and previous reports The latest data contained in this study are from 1997 Range Fires Characteristics Reported in National Fire Data and a CPSC Special Study Linda Smith et al US Consumer Product Safety Commission Hazard Analysis Division Directorate of Epidemiology and Health Sciences January 1999 The primary statistics that we used from these reports are as follows e Surface cooking represents between 73 83 of cooking fires depending on the analysis e Depending on the analysis between 58 85 of the surface cooking fires were unattended at the time of ignition e Cooking materials were ignited first in 72 77 of surface cooking fires e Half of homeowners who attempted to fight a cooking fire did the wrong thing e The cooking materials that do ignite are primarily greases oils meats fish or starches We used these statistics in the following aspects of our evaluation work e The basis for focusing on surface cooking fires was confirmed The significance of both unattended cooking and the ignition of cooking materials as factors in cooking fires was confirmed e We eliminated all patents technologies products or concepts that required a person to approach the fire or address it manually in any way We eliminated these approaches because the statistics indicated that half of people who attempt to respond to a kitchen fire do the wrong thing Fire marshals recommend le
102. larm Can operate within reasonably foreseeable misuse conditions durability Looks good but not data It is just a simple timer and alarm Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop will not work if no signal of heat source power level was received Safety system components might pose added risk to consumer Nothing is expected Applicability across product types and product models Will need more development to apply for gas cooktop specifically for the power level sensor No patent found that specifically address this type of technology on gas cooktop although it does not seem difficult to do Components system availability Most parts are available off the shelf or has been manufactured at high volume at low cost Installation No added effort than installing conventional range Serviceability Some training or new equipment is necessary for servicing the sensor PREVENT FOOD IGNITION IN PAN ELEC SIGNAL PROCESSING SELECT MODE OR T T SENSOR CONTACTS POT Effect on Cooking Process All cooking process is possible as long as T range determined is high enough for high temperature cooking searing Effect on Cooking Time Likely to affect cooking time by less than 10 Effect of System on Consumer Behavior While Operating the Cooktop User need to read the manual to use the new mode selecting control knob or buttons without the need to r
103. ls CONTACT T SENSOR MEASURE PAN BOTTOM T NO SIGNAL PROCESSING USE BIMETAL SENSOR CONTACT T SENSOR MEASURE PAN BOTTOM T NO SIGNAL PROCESSING USE EXPANSIBLE LIQUID SENSOR CONTACT T SENSOR US 5945017 JP 6265158 Tpan is used to determine near fire condition it is bypassed if motion sensor detect person near stove within a pre set period It resets again after person is detected If no motion detected burner turns off Tpan bottom Tthres controller counts set time if during set period no motion person is detected heater off If yes controller reset counting and continue if set period is passed heater lowered off None TOSHIBA CORP JP 7083442 User select button for frying function actuate safety circuit If no T change is determined from the IR motion sensor at the front of stove burner will turn off after a specified time 10 min TOKYO GAS MOTION Tpan SENSOR amp MICROPROCESSOR TO ACTUATE CONTACT T SENSOR US 5796346 JP 6050551 US 5416301 To prevent fire from foreign object eg grease that touches heating element to accidentally burns When power level heater above a threshold value timer and possibly alarm will turn on Depending on the measure power level a a corresponding pre set time will start to be counted down by the timer If by the time the timer ends the count down the user does not provide action e g press reset button burner will turn off automatically Pre set tim
104. lse negative if sensor is dirty and did not register the actual cooking pot temperature Can Operate Over product life w o failure safety factor of 2 No data looks problematic sensor window might get soiled w grease and food that might require replacement Some model requires sensor to move up and down from cooktop s surface this might get soiled and jammed Can operate within reasonably foreseeable misuse conditions durability No data looks good Sensor is located away from the pot and pans traffic during cooking Chance of impact with cooking pot pan is minimal 19 20 e Safety system s effect on cooktop s conformity with current safety standards UL ANSI Need to fail safe cooking system shut down Cooktop can still operate even though the safety system might not be working e g Bosch s in the market model becomes conventional cooktop when system is not working Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work on all models of the same type Components system availability Most parts need development Installation No different than conventional cooktop Serviceability Needs new training and some new equipment PREVENT FOOD IGNITION IN PAN ELEC SIGNAL PROCESSING AUTO ACTIVATION T SENSOR CONTACTS POT e Effect on Cooking Process High temperature cooking searing is negatively affected e Effect on Cooking Time Proba
105. lso the protruding sensor is not practical in real cooking scenario GRI 28 Fire Line Hood installed extinguisher using fusible link Ansul Fire Suppression System is applicable for commercial kitchens System 29 Firemelt hood Hood installed extinguisher using fusible parts and a new powder extinguisher Firemelt No clear description of product and company system that suppse to work well with grease fire too did not return contacts Appendix C Cooking Process Definitions COOKING METHODS DEFINITIONS 1 Saut To saut is to cook a food quickly in a small amount of fat over a relatively high direct heat First heat the pan over a medium flame then add your fat Once the fat begins to ripple add your ingredient It is very important not to crowd the pan or the liquid released from the food will actually cause steaming rather than saut ing Searing To sear means to cook food over a very high dry heat to seal a surface and seal in juices This is usually done in a skillet or under a broiler The high heat caramelizes the naturally occurring sugars present in the food and produces a flavorful crust Browning becomes apparent when the food s surface reaches approximately 310 F Stir fry To stir fry means to cook food quickly stirring constantly over extremely high heat in a small amount of fat This technique is traditionally performed in a wok Since the heat is intense it s best to use a fat with a high s
106. luate Selected Technology Classes iii vcsicnceieres ha eee 3 3 4 ReSUINS 2 2 d eee iain hin RRR 4 1 4 1 Patents Products Technologies Systems Concepts csceeeseceeeteeeeeees 4 1 4 2 Technolo 8 yC lass eS n E EE R 4 2 A3 SCTE CIID S CTIE A a E E E 4 25 4 4 Additional Consideration for Technology Evaluation eee 4 29 GAT Cooking Processes ics cs tatcauni ates asa a suiucl seu wei einen 4 29 4A 2 Cooking PING ninan a a aa a a a aa 4 29 4 4 3 Fire incident statistics used sinsicscccssnsccovssh eves cauas oeecaantectamaseseccaansecee 4 34 4 4 4 ROL ADU TEV TOUT DULY sce ian sisie Saeed Saat ea wa ded dds ay US ncaa 4 36 AAS Product Classes onene eE e E EE ET REESE 4 37 AS Technology SCree i ssc yes sada decssesve tae ot e ES EEEE 4 38 416 Selected PeGhnol CBG sos ses r E EE O E A 4 40 4 7 Technology Evaluation oeneeneeneeoeneossesrsoersooersoseesssssessseersooersosssnssssessee 4 41 4 7 1 Detect and Extinguish Surface Cooking Fires cccccccccccssssceeesees 4 41 4 7 2 Prevent Unattended Cooking Warning and Control 00 4 44 4 7 3 Prevent Unattended Cooking Warning and Control 00 4 49 4 7 4 Prevent food ignition in the pan electrical signal processing auto Activation T sensor contacts PO csssseccccessececeessececeessseeesseseeeeees 4 50 AS Results Summary ccsiaccescsieawer ease deii a r E E E 4 54 O a REE T A TT ETT Appendix A Complete List of TechnologieS
107. ly automated fire detection and extinguishing system for surface cooking fires The system includes a fire extinguishing cylinder assembly that is located above or to the side of the ventilation hood and extinguishing agent nozzles located under the hood There are two approaches to detect the presence of a fire In one option a fusible link melts at sustained temperatures of 289 to 370 F above ambient This is a mechanical system that acts against a spring loaded trigger for the fire extinguishing agent An alternative detection approach is a temperature sensor This approach requires an electronic controller to activate the extinguisher In either case the extinguishing agent is most generally a potassium based wet chemical specifically formulated to extinguish grease fires Sealed in the cylinder the agent is good for 12 years When a discharge occurs the system will cut the supply of gas with an electronic solenoid cut off valve Pressing a reset button on the solenoid valve restores gas flow If the range needed to be moved for this process it may need to be repositioned by a service technician to ensure the proper use of the anti tip system With an electric range the system will cut the power to the range Resetting the circuit breaker in the home s electrical panel restores power 4 41 The cylinders are rechargeable In case of a discharge the homeowner would bring the cylinder to a local fire protection equipment dealer or possibl
108. misuse conditions durability Looks problematic but no data smoke sensor can get soiled and covered up by airborne cooking or grease particles Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop will still operate even though the safety system is off Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work for all models for one product type for vented or non vented hood and under cabinet hood or free standing ones need different solution for non hood instalation such as downdraft or island installations Components system availability Most parts have been manufactured but not in high volume and low costs some need to be adapted from other industry Installation Need additional tradesmen to install the alarm extinguisher and heat sensor Serviceability Specialized equipment and or staff expertise or licensing is necessary DETECT FIRE WARNING ONLY NON OPTICAL T SENSOR Effect on Cooking Process None does not affect the operation of the cooktop Effect on Cooking Time None does not affect the operation of the cooktop Effect of System on Consumer Behavior While Operating the Cooktop None alarm will only activate when temperature sensor measured a relatively high ambient temperature Limits availability or efficacy of marketed cooktop features None Eas
109. moke point such as peanut canola corn or safflower oil or lard The wok must be very hot before the fat is added or the fat and food will stick Blackened Meat or fish is cooked in a cast iron skillet that s been heated until almost red hot The food is customarily rubbed with a cajun spice mixture before being cooked The extra hot skillet combined with the seasoning rub gives food an extra crispy crust Browning To cook quickly over high heat causing the surface of the food to turn brown while the interior stays moist This method not only gives food an appetizing color but also a rich flavor Browning is usually done on top of the stove but may also be achieved under a broiling unit Caramelize To heat sugar until it liquefies and becomes a clear syrup ranging in color from golden to dark brown from 320 degrees to 350 degrees F on a candy thermometer Blanching The term blanching refers to the technique of plunging a food usually a vegetable or fruit into boiling water until either its color has set or the food has softened slightly This takes anywhere from a few seconds to several minutes depending on what is being blanched Parboiling It is a technique that is similar to blanching but takes a bit longer Parboiled food is actually partially cooked Melting Chocolate Chocolate scorches easily melt slowly over low heat Place the chocolate in a double boiler over simmering water remove from heat when halfway melted a
110. mperature sensor and cooktop did not have good contact due to surface dirt or misalignment Can Operate Over product life w o failure safety factor of 2 Looks problematic no data Sensor is unprotected Can operate within reasonably foreseeable misuse conditions durability Looks problematic but no data Sensor is out in the open and have high likelihood to be impacted by cooking wares Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Depending on the algorithm selected On some system where cooking modes need to be selected cooktop will still work even though the safety system is not on operating on others cooktop will not work since user has to input foodstuff temperature for the cooktop for maintain when turning on the control knob Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work for all models of one product type Components system availability Most parts are new parts that need to be developed and manufactured Installation No different than conventional range Serviceability Current staff needs some training and or new equipment to test service the sensor PREVENT FOOD IGNITION IN PAN ELEC SIGNAL PROCESSING SELECT MODE ORT NON CONTACT T SENSOR Effect on Cooking Process All cooking process is possible as long as T range determined is high enough for
111. n controled Since there is high probability that fire has commenced when the system is triggered the sensor can be damaged from the high heat due to no provision to quickly extinguish the fire once it is detected Potential for False Actuation Potential for false negative when sensor is not properly cleaned and might miss a fire incident Sensor location is not in area that will be part of daily clean up Can Operate Over product life w o failure safety factor of 2 Looks problematic but no data Sensor optical window can easily get covered up with airborne cooking oils particles and needs calibration Can operate within reasonably foreseeable misuse conditions durability Looks good but no data Sensor is away from user s reach Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop wills still work even though the safety system is not operating off Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work for all models for one electric product type but need other approach on island installation or others where there is no wall or hood space to locate the sensor alarm Probably not be applicable for gas cooktop since the open fire from the burner can be mistaken as cooking fire Components system availability Needs to be developed and manufactured or adapted from other in
112. n existing fire data Probably will catch less than 40 of cooking fire incident since it will only warn user that cooking is unattended and heat source is set at dangerous level If user is far enough from the kitchen not to hear the alarm then the system is useless Percent of new product sales covered by this technology Less than 90 since it needs more development work for gas cooktop power sensor The degree of mitigation of fires addressed Only warn of possible pre ignition condition Effect of Safety System on Cooktop Performance After Actuation of System None provided user act on the alarm no extra cleaning or adjustment is necessary Alarm will turn on before fire is occuring Effect of Actuation on the Safety System User might have to reset the mechanism once system alarm is on Potential for False Actuation Potential for false negative depending on the selection of limiting power level Food oil can still get really hot with lower power setting And user might put a pot with an already hot food content Potential of false negative if the motion sensor is not calibrated to detect only adult user mistaken pets or children as responsive adults Can Operate Over product life w o failure safety factor of 2 Looks good but no data Can operate within reasonably foreseeable misuse conditions durability Looks good but no data Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe co
113. nd stir until smooth 4 ounces of chocolate takes about 3 min 10 11 12 Simmering To cook food gently in liquid at a temperature about 185 degrees F low enough that tiny bubbles just begin to break the surface Cooking time varies from short less than 10 minutes to long more than 1 hr Canning Boiling Water Canners These canners are made of aluminum or porcelain covered steel They have removable perforated racks and fitted lids The canner must be deep enough so that at least 1 inch of briskly boiling water will be over the tops of jars during processing To ensure uniform processing of all jars with an electric range the canner should be no more than 4 inches wider in diameter than the element on which it is heated Cooking time is between 10 45 min depending on type of canner used and type amount of food canned Boiling canner has a large diameter found one w 16 5 diameter Pressure canner w diameter of 12 25 to 15 25 Braising A cooking method by which food usually meat or vegetables is first browned in fat then cooked tightly covered in a small amount of liquid at low heat for a lengthy period of time Can be gt 1hr The long slow cooking develops flavor and tenderizes foods by gently breaking down their fibers Braising can be done on top of the range or in the oven A tight fitting lid is very important to prevent the liquid from evaporating Appendix D Temperature Measurements from ADL Cookin
114. nded cooking can be prevented All these technologies involve the use of a motion sensor to detect the presence of a person near the range A description of motion sensor technology is provided below Motion Detectors Motion detectors can be grouped into two categories passive and active Passive sensors do not emit any energy they only look or listen for changes to the environment Active sensors emit a form of energy and then look for an echo of the transmitted energy Passive Sensors Passive sensors use an infrared detector to detect differences in heat These systems are often referred to as PIR passive infrared The systems usually consist of a plastic lens that focuses the IR energy onto one or more solid state IR sensors The lens allows the unit to have a wide field of view FOV and still only one or two sensing elements The sensors are tuned to be most sensitive to the surface temperature of the human body 4 44 around 93 F or as radiated infrared energy between 9 and 10 micrometers Thus most sensors are most sensitive in the range of 8 to 12 micrometers When these sensors detect a change of energy in the form of heat they become excited and output a signal The microprocessor connected to the sensor then determines if the change occurred quickly enough and was large enough to trigger the system The sensors have a 5 year warranty Since the sensor has no moving parts there is nothing that could be considered a wear item
115. ng boiling and maintaining the boil of 8 quarts of water for 4 6 hours In addition we added the following cooking processes to the list e Putting a kettle on to boil and leaving the kitchen and e Preparing a flamb wherein the alcohol poured into a pan is burned off We used these cooking processes as a benchmark to evaluate whether fire mitigation technologies would work well with all surface cooking functions A complete list of the definitions we have used for specific cooking processes is included in Appendix C 4 4 2 Cooking Time The effect of a fire mitigation technology on cooking time is an area of considerable concern for the industry Market forces are continuously demanding cooking technologies that provide added convenience In surface cooking this market demand 4 29 translates into the need to reduce the time required to bring foods to their desired temperature e g the time to boil or the time to heat oil to the desired temperature There is general industry concern that a technology that limits the pan temperature to below a pre ignition condition could have an adverse affect on cooking time In addition there is general concern that the temperature at the bottom of the pan may not accurately indicate the temperature of the cooking materials in the pan Some of the tests conducted by Good Housekeeping on the CPSC cooking control prototype showed significant increases in cooking times for certain
116. ng high temperature cooking Simmer boiling will not be affected since it s temperature is well below food ignition temperature e Effect of System on Consumer Behavior While Operating the Cooktop Consumers need to read manual to figure out that cooktop will alarm and manipulate burner when it is left alone while cooking vessel temperature is relatively high e Limits availability or efficacy of marketed cooktop features None e Ease of System Verification Need specialist help to verify the operation of safety system e Safety System Maintenance Need additional procedures to clean the temperature sensors regularly from grease of food soil buildup Cleaning the motion sensor surface is not more than wiping off the front sensor wondow cover which is part of the regular daily cooktop cleaning e Cookware Applicability Some cookware materials or shape can compromise safety system performance since the sensor will need to be in contact to the cooking vessel e g glass ceramic ware cookware with concave bottom e Range of Fire Incident Coverage Based on existing fire data Should cover at least more than 50 of the cooking fire incidents due to unattended cooking e Percent of new product sales covered by this technology Multiple designs applicable for gas and solid or coil electric elemet cooktops Has some design for smooth top Ceran gold alloy track but the application might be more difficult for a reliable means to gauge pot content temperatur
117. nsor Timer Tech Class 13 This approach to prevent unattended cooking has no motion detector Instead an alarm and control will activate based on the power level selected and a timer that is a function of the power level Specifically a time interval is associated with the power level of the element or burner this could be implemented with relays and may not require an electronic micro controller A timer will trigger an alarm to sound after the element or burner has been turned on The user would press a re set button to establish user presence near the cooktop If the re set button were not pushed the control would turn off power to the element or gas to the burner There are numerous possible variations of this approach In one configuration the control and alarm system actuates only above a minimum power level i e activates only when element or burner is set higher than medium low POWER HIGH POWER LEVEL aENSoR O apm APTER SET TIME High Pwet amp REDUCED F RESET BOTTOA IS NoT PRESSE Figure 4 13 Prevent Unattended Cooking Warning and Control Power level sensor timer 4 15 Prevent Unattended Cooking Warning Only Motion Sensor Only Tech Class 14 The next three technologies attempt to prevent unattended cooking through the use of a warning only There is no follow up control that would shut the unit down or reduce input in case no user is detected In this case a mo
118. nter 800 1000 Time s PBE pan bottom edge 1200 1400 CPSC TC built in thermocouple 1600 D6 Temperature F 1000 800 600 400 200 100ml Oil Test in Cast Iron Pan on CPSC Gas Range smoothed data 15 sec moving average CPSC TC 200 400 600 PC pancontents PBC pan bottom center 800 1000 Time s PBE pan bottom edge 1200 1400 CPSC TC built in thermocouple 1600 D7 Temperature F 1000 800 O Q oO A a 200 100ml Oil Test in Stainless Steel Pan on CPSC Electric Range no ignition after gt 30mins 0 200 PC pan contents 400 600 PBC pan bottom center 800 Time s PBE pan bottom edge 1000 1200 1400 TC1 TC2 and TC3 built in thermocouples 1600 D8 Temperature F 1000 800 600 400 200 100ml Oil Test in Aluminim Pan on CPSC Electric Range PBC AENA E AREA EAA PB E PNT Wy no ignition after gt 20mins 0 200 PC pan contents 400 600 800 1000 1200 Time s 1400 PBC pan bottom center PBE pan bottom edge 1C1 TC2 and TC3 built in thermocouples 1600 D9 Temperature F 100ml Oil Test in Cast Iron Pan on CPSC Electric Range no ignition after gt 30mins 200 PC pan contents 400 600 PBC pan bottom center 800 Time s PBE pan bottom edge 1000 1200 1400 TC1 TC2 and TC3 built in thermocouples
119. ntly impact service to the cooking unit However there are some current limitations regarding applying a power level sensor to gas units We know of no existing system that would provide an accurate power level sensor for gas fired units The development of such a sensor would be straight forward but would take an effort Product life may be an issue in the use of motion sensors and their associated electronics As indicated above the motion sensors have a five year warranty but typically last 10 or more in the field These motion sensors are in many homes now as part of security systems However there is no data that suggests that the motion detectors can provide a 20 year product life with a safety factor of 2 There is no obvious reason that the motion sensor electronics should have a shorter life than the electronic controls currently in cooking appliances but this potential for life would need to be tested 4 47 Potential Effectiveness of Technology to Mitigate Cooking Fires If all the unattended cooking fires could have been avoided by having a person attending to the range these technologies would eliminate between 65 and 70 of all surface cooking fires Unlike a fire extinguishing approach these systems are intended to prevent a fire from starting The fire would be avoided rather than extinguished In the systems defined by the referenced patents the operation of the safety system could be verified manually but not automaticall
120. odstuff at proper temperature no reset is necessary after each actuation Potential for False Actuation Potential for false negative if temperature sensor and cooktop did not have good contact due to surface dirt or misalignment Can Operate Over product life w o failure safety factor of 2 Looks problematic no data Sensor is unprotected Can operate within reasonably foreseeable misuse conditions durability Looks problematic but no data Sensor is out in the open and have high likelihood to be impacted by cooking wares 22 23 Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Depending on the mechanical design on some cooktop can still work when safety system is off On other designs cooktop cannot be turned on when the sensor is broken Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work for all models of one product type except on smooth top cooktop Ceran Components system availability Most parts are new parts that need to be developed and manufactured Installation No different than conventional range Serviceability Current staff needs some training and or new equipment to test service the sensor PREVENT BOIL DRY SPILL OVER T SENSOR Effect on Cooking Process Will not affect any cooking process since user needs to select boil cooking mode for system
121. oking and Frying control using a gas sensor microarray A discussion on a new development effort on a gas sensor microarray that is specifically to determine the doneness level of steak cooking The sensor is located on the underside of the pan lid Institut fur Instrumentelle Sensor can only judge the doneness of Analytik meat during steak frying only Still at early stages of development 24 Conference paper Fire Detection w Combined Ultrasonic Microwave Doppler Sensor A description of a new development of a fire detection system that combined two sensors ultrasound and microwave Doppler sensor to reduce the incidence of false alarms Sensor is still at early stage and looks to be too expensive an addition to cooktop or hood Siemens AG 25 Fire Breaker Fuel Neutralizer Manual fire extinguisher material powder in bottle National Fireproofing Co User has to manually spray the product on the fire considered unsafe proximity 26 Stovetop FireStop 27 Simmer Sentry Hood installed magnet extinguisher No pressurized tank Tsensor acoustic sensor directly in contact w food The sensor sticks out of the back panel of the cooktop and its sensor tip is immersed in the cooking liquid Williams Pyro Inc Product not applicable for grease fire since it is released w large pressure that can splatter the grease and fire to surrounding Only to detect the presence of boiling in liquid cooking A
122. oking system shut down Cooktop will not operate when no signal from either motion or power level sensor is received Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Will need more development to apply for gas cooktop specifically for the power level sensor No patent found that specifically address this type of technology on gas cooktop although it does not seem difficult to do Components system availability Most parts are available off the shelf or has been manufactured at high volume at low cost Installation No added effort than installing conventional range Serviceability Some training or new equipment is necessary for servicing the sensor PREVENT UNATTENDED COOKING WARNING ONLY POWER LEVEL SENSOR TIMER Effect on Cooking Process None nothing affected the burner operation Effect on Cooking Time None nothing affected the burner operation 17 Effect of System on Consumer Behavior While Operating the Cooktop user need to read manual to learn that to he she needs to be present near the cooktop to either stop or avoid the actuation of alarm by occasionally turning the knob or pressing a reset button Limits availability or efficacy of marketed cooktop features None Ease of System Verification User can easily verify system operation by setting the power level to high and see if the alarm will turn on after a pre determined time has elapsed
123. oking utilizes a power level sensor and a timer to warn the user to attend the cooking process An alarm will activate based on the power level selected and a timer that is a function of the power level Specifically a time interval is associated with the power level of the element or burner this could be implemented with relays and may not require an electronic micro controller A timer will trigger an alarm to sound after the element or burner has been turned on The user would press a re set button to establish user presence near the cooktop In one system configuration the system is actuated only at a power level above a minimum threshold level Rwee LABEL sFHsor l l T i TIME ALARM APTER PRE SET TIME AT INEN POWER LeveL Figure 4 16 Prevent Unattended Cooking Warning Only Power level sensor timer 4 18 Prevent Food Ignition in Pan Elec Signal Processing Select Mode or T T Sensor Contacts Pot Tech Class 17 The next five technologies are intended to prevent ignition of cooking materials in the pan There are a number of approaches to control the heat input to the pan to avoid ignition In this configuration the safety system monitors the pan bottom temperature with a pan contact temperature sensor e g thermocouple The controller is defined by a user selected cooking mode e g searing boiling frying or a specified cooking temperature A microprocessor control
124. omparing Tmax Tmin with a reference value and by the time it takes for T to rise from 220 to 240 deg C TOKYO GAS CO LTD RINNAI CORP RINNAI CORP JP 8233278 Thermistor detect Tpan bottom amp connected to valve coil of safety valve through intermediate switch At pre set Tthres thermistor operates the switch and turns off heat Osaka Gas Co Ltd JP 4236012 JP 61105025 Cooking mode is auto judged by bottom pot temperature moisture sensor liquid cooking frying Prevent over cook boil simmer or fire frying by temperature rise pattern of pan pot bottom Use electromotive force of TC for pan bottom If this becomes larger than V drop of an electric resistance signal is processed to output a pulse for heat source If beyond Tthres gas valve turns off Matsushita Electric Ind Co LTD Matsushita Electric Ind Corp JP 9148062 ELECTRIC JP 4020718 Ctrl Sys For Preventing Food Ignition on Gas RI Pan pot bottom T is measured by a T sensor below ceramic heat resistant slab for electric stovetop When abnormal T is detected heat source is manipulated stop heat retaining or low In addition to overheat preventive function Tpan bottom based A contact sensor is installed to detect pot pan on burner tripod grill If no pot is detected alarm is on after a pre set period A TC based T sensor for pot bottom to determine the arrival of pre ignition cond T threshold of 590F was selected When Tpan gt 590F bu
125. ooking fire incident since it only warns user that nobody is near the cooktop If cook is far enough from the kitchen not to hear the warning then it is useless Percent of new product sales covered by this technology Should be able to cover more than 90 of new product sales The degree of mitigation of fires addressed Only warns user of possible cooking fire Effect of Safety System on Cooktop Performance After Actuation of System None as long as user hears the alarm and return to kitchen Cooktop should perform normally since no control is applied to cooktop Effect of Actuation on the Safety System Depends on algorithm selected alarm will turn off when user presence is detected again or user still needs to reset system by manipulating a button or a knob Potential for False Actuation Potential for false positive when user simmers food on pot and leaves it alone Potential for false negative where sensor might mistaken pets curtains or small children can be eliminated using appropriate sensor data analyzing algorithm Can Operate Over product life w o failure safety factor of 2 Looks good but no data Can operate within reasonably foreseeable misuse conditions durability Looks good but no data 15 16 Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Alarm will continually turn on if cooktop is operated and no signal from motion sensor is dete
126. ormance After Actuation of System None cooktop is performing normally as the system actuates continuously Effect of Actuation on the Safety System None system resets automatically whenever boil mode is selected Potential for False Actuation Potential for false negative if temperature sensor and cooktop did not have good contact due to surface dirt or misalignment Can Operate Over product life w o failure safety factor of 2 Looks problematic no data Sensor is unprotected Can operate within reasonably foreseeable misuse conditions durability Looks problematic but no data Sensor is out in the open and have high likelihood to be impacted by cooking wares Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop might still work if safety system is off Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work for all models of one product type except Ceran cooktop Components system availability Most parts are new parts that need to be developed and manufactured Installation No different than conventional range Serviceability Current staff needs some training and or new equipment to test service the sensor NO COOKTOP FIRE PREVENTION TECHNOLOGY DO NOTHING Effect on Cooking Process None Effect on Cooking Time None Effect of System on Consumer Behavior Whil
127. out device made of temperature limiting rod is embedded beneath the hotplate for precision cut off when Thot plate gt Tthreshold T sensor for pan bottom temp T rise gradient at initial state of heating for a certain time is used as correction value for pan type T rise gradient after certain T has been reached is used as correction value for amount of food They are converted into preset T values for operating T for T sensor Once the T operation is reached heating is maintained A Tcut off also calculated from the operating T E G O Elektro Gerate Blanc U Fisher Matsushita Electric Ind Co LTD JP 8014573 JP 7012335 JP 5044939 A load sensor determine if there is pan not on top of burner When there is pan a Tsensor which measure pan bottom T will determine if Tbottom gt Tthreshold A if No combustion is continued if Yes empty boil over heating detected gt turn off flame If no pan detected amp Tsensor measure Tbottom gt Tthreshold B pan is temporarily removed shaken gt reduce to weak flame Tsensor detect pan bottom Temp When Tpan bottom gt Tthreshold for a pre determined time period Cut off gas valve If Tpan bottom gt Tthreshold temporarily lt pre determined time then nothing is done Reduce nuisance burner turn off due to shaking of pan or temporary pan lifting flipping pancake Tpan bottom measured every 0 32s Tmax Tmin between 4 consecutive T measurement is calculated Oil fire is prevented by c
128. p User will need to read the manual to learn that burner will manipulate heat when he she leaves cooktop area Simmering will need attendance Limits availability or efficacy of marketed cooktop features None Ease of System Verification User can verify easily if system is on or off by turning the burner and leaving the room and see what happens Safety System Maintenance Cleaning the sensor surface is not more than wiping off the front sensor window cover which is part of the regular daily cooktop cleaning Cookware Applicability Any utensil at any environment will work Range of Fire Incident Coverage Based on existing fire data Will at least address unattended cooking 53 5 of fire incident from NFIRS NFPA data from 1994 1996 Percent of new product sales covered by this technology Should be able to cover more than 90 of new product sales The degree of mitigation of fires addressed Will prevent a fire due to unattended cooking from starting Effect of Safety System on Cooktop Performance After Actuation of System None fire will not even start so cooktop should be ready to work normally again after safety actuation Effect of Actuation on the Safety System Depending on the algorithm used On some safety system should be ready to work normally again once user presence is detected On others user has to reset the system manually 11 e Potential for False Actuation Potential for false positive when user is leaving a pot of food to
129. power of the electrical heating element Whirlpool Corp RT L5500GFT R TC based T sensor for pan bottom Temp For frying oil select 3 preset temps and controller maintain burner Boil ctrl once boiling is detected alarm on turn down burner wait 5 min then turn off burner Can detect stew cooking is boil dry or when cooking vessel is empty auto off If food content T Tgrease fire burner auto off then alarm on When boil over happens and spill over food turns off burner gas valve auto off Burner auto off when on for more than 2 hrs Rinnai Ceramic cooktop w integrated temperature sensor Cook can select the cooking temperature Claims tat Tsensor can be used to detect boil over boil dry and contaminated pot pan surface which will affect heat transfer to pot pan and can be applied to prevent oil grease fire problems Also claims quick and even heating due to its coper aloy construction and the ceramic plate can cool in 30 seconds A sensor at the center of an electric hot plate will contact cooking vessel and detect vessel presence and vessel bottom s temp indicator only Will cut off electrical supply to hot plate when sense max T is reached by a fuse connected to vessel bottom which melt at that T Ecowatt Schweitz AG SEB S A Selongey France US 4723067 ELECTRIC US 4492336 A sensor at the center of an electric hot plate will contact cooking vessel and detect vessel temp A separate temperature cut
130. quantities of water to boil normally with no safety system acting Frying was simulated by heating oil on the Rinnai burner using the setting that is designed to maintain the highest optimum temperature for frying food 390 F Steaks were pan seared by an experienced cook again with no safety system acting The figures below show the temperature ranges involved in the different processes The first figure shows food temperatures The second figure shows pan bottom temperatures 4 31 Food Temperature F Figure 4 24 Temperature of pan contents during various cooking procedures 1000 900 Pan bottom temperature F Figure 4 25 Temperature of pan bottom at center of pan during various cooking procedures These figures indicate that the temperatures reached by both the food and pan bottom during normal cooking procedures are significantly lower than those experienced when ignition occurs With an accurate robust method of measuring pan temperature it would in theory be possible to implement a threshold based temperature control algorithm that should prevent ignition from occurring without affecting normal cooking The issue is one of engineering design not of fundamental principles However the two prototype systems that we tested demonstrated the difficulty of designing an accurate pan bottom temperature sensor for this application Both the electric and gas cooktops used spring loaded thermocouple temperature probes tha
131. r in Cast Iron Pan 1000 800 i 600 3 ignition 713s 5 5 o Q 5 400 200 0 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge D15 Searing Steak in Stainless Steel Pan on CPSC Gas Range 1000 800 T 600 2 8 Q 5 Ee 400 200 meat turned meat added PC center of steak 0 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge CPSC TC built in thermocouple D16 Searing Steak in Aluminum Pan on CPSC Gas Range 1000 800 T 600 2 T oO 2 5 F 400 CPSC TC meat turned 200 meat added Te ae center of steak 0 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge CPSC TC built in thermocouple D17 Searing Steak in Cast Iron Pan on CPSC Gas Range 1000 smoothed data 15 sec moving average 800 om CPSC TC Temperature F 400 meat turned 200 PC center of steak 0 200 400 600 800 1000 1200 1400 1600 Time s PC pan contents PBC pan bottom center PBE pan bottom edge CPSC TC built in thermocouple D18 Temperature F D19 1000 800 600 400 200 Searing Steak in Stainless Steel Pan on CPSC Electric Range meat turned 0 200 PC pan contents 400 PBC pan bottom
132. r the operation of the cooktop There are other areas in which the technology does not score highly related to ease of installation and service the ability of the technology to fail safe and the impact of system actuation on the cooktop and the safety system itself With regard to the effectiveness in mitigating fires it is triggered by the presence of a fire so some damage may already be done before the safety system actuates It is not readily applicable to installations on islands or in association with cooktops with integral downdraft ventilation systems 4 39 2 Detect and Extinguish Fire Non optical Temperature Sensor for Fire Detection Tech Class 2 This technology is a minor variant on the technology described above It scored very similarly 3 Prevent Unattended Cooking Warning and Control Motion sensor only Tech Class 10 This technology will have an impact on consumer behavior and available cooking processes It scores highly in safety system effectiveness because it is intended to prevent a fire from igniting it is applicable to most product classes can be made to be fail safe The basic assumption here is that if a significant amount of fires occur when someone is out of the kitchen then requiring the cook to remain in the kitchen will prevent these fires from occurring 4 Prevent Unattended Cooking Warning Only Motion sensor only Tech Class 14 This technology scores similarly to the one
133. rability reliability durability safety and manufacturability of cooking products Reliability is a significant issue to the industry It includes the requirement that a safety device would address all fire incidents that it was intended to address throughout the life of the appliance In all cases the system would need to fail safe in that the range would need to shut down in case the fire safety device were not working properly The CPSC requested the assistance of Arthur D Little to conduct a study to evaluate the technical practical and manufacturing feasibility of range modifications intended to address the ignition of cooking materials The Association of Home Appliance Manufacturers provided additional support to expand this study to include technological solutions beyond the rangetop such as fire suppression systems to address the broad spectrum of surface cooking fires To focus the scope of this study only surface cooking fires and surface cooking fire mitigation technologies were considered Surface cooking fires include the ignition and combustion of materials on cooktops or rangetops These materials are primarily cooking materials but can be paper trash cabinetry fuel accelerants or unclassified items The 1996 report entitled Ten Community Study of the Behaviors and Profiles of People Involved in Residential Cooking Fires written by the Cooking Fires Task Force of the National Association of State Fire Marshals NASFM
134. reai element o ava cso 2 Cost Analysis of CPSC Range Control Prototype heating element AHAM CPSC Kitchen range Fire safety device system for surface List of acceptance criteria of fire safety device system and list Po 13 elements burners ist for design criterias of several fire systems developed or in development AHAM member 14 NFPA NFIRS Fire Data Review on how NFPA amp NFIRS collect their fire data STP members 14 Product Tite Cherry Sensors and 1 Control Standard Comfort Module Controllers for ceramic top electric cooktop Paper brochure Controllers for ceramic top electric cooktop Describe various Cherry Sensors and Design Freedom We make cooktops sensors that can be included with the controllers including a 2 Control smarter temperature sensor for cooking vessel Paper brochure Cooking Sensors Pan temp IR 4 mart Hob RB 3EMB 5 Fire Line iremelt EM ALL Fire exting Fire Suppression System Corp Detect Suppress Alarm Hood installed extinguisher Web printout Dn v 71 7 Cook settings and Auto quick boil Stove Alarm and Stove Cutout for Cabinova AB Swesen Electrical Stoves Wall mounted alarm Stove power cutout device Web printout Figaro Gas sensors General Information hin film metal oxide semiconductor gas sensors Paper brochure T immer Sentry Tsensor acoustic sensor directly in contact w food Paper brochure T S 5 Gas Thermal Eye with Flame Set sensor for bottom of cooking vessel Paper bro
135. rease temp Cook modes boil mode warm simmer boil and fry mode and regular Hi Med Lo settings available Detect boil dry condition when in boil mode When rate of increase of Tpot exceeds a predetermined reference rate or the sensed Tpot exceeds a predetermined threshold temperature If Tsensor fail indicator signal user amp it becomes conventional cooker Cook modes boil mode warm simmer boil and fry mode and regular Hi Med Lo settings available Each mode is associated w a min SS temp and a SS power level Ctrler compares Tpot amp current power setting to selected mode settings and adjust to reach the Tthres quickly w minimum overshoot If Tsensor fail same as above Cooking T To is set by switch Once it is achieved Tpan bottom flame is reduced Microprocessor then set Tthres To DeltaT pre set in prog If after flame reduction Tpan gt Tthres turn off burner For cooking with small food content None None Sanyo Electric Co Ltd General Electric Company General Electric Company OSAKA GAS CO LTD User selected switch If on If Tpan bottom gt Tthres burner switches on and off to maintain Tthres When switch is off If Tpan bottom gt Tthres burner switches off and remains so Gas valve is latching solenoid valve if switch is on amp Tpan Tthres resistance in wire reduce amp valve open Matsushita Electric Ind Co LTD JP 5052336 User select cook modes boil or fry If boil i
136. ression system concealed in hood or in kitchen cabinet above range When fire detected using fusible parts within hood auto shuts off fuel supply to stove gas amp electric while releasing extinguisher Optional audible alarm amp pull stations 9B The Guardian US 4773485 Patent Description Company A flexible incombustible curtain automatically drops over and contained cooking unit once Mon Arec Inc fire is detected then gas fire extinguisher released inside the partitioned area to avoid messy cleanup 2 US 6105677 Can s of particulate extinguishing mat l inverted above range in hood Cap has fusible mat l None that melt at Temp 220 F releasing particulates that fall on cooktop by gravity 3 US 3889754 Dry fire extinguish powder avoid splatter of grease Auto deploy fusible parts that lets go a None spring actuated puncture for CO2 canister which allow pressurized deployment of extinguisher ceiling panels Firemelt powder switch to turn off stove 6 US 6032663 A fusible part nylon cord webbing extended above stove is used as fire detection device None Once flame melt the webbing this releases the gas valve electric switch which was held in tension so burner is off 7 Ansul System In hood fire detection and suppression system Fire detection and suppression actuator Reliable Fire is a fusible links which will cause cartridge to propel gas into Ansulex liquid agent tank Equipment 8 The Safety Waiting for Broc
137. rm that the tanks were charged and at the appropriate pressure This implies that the system would need electronics and a self diagnostic system Another issue relates to system life The pressurized cylinders need periodic hydrostatic tests to ensure that they have no cracks or leaks The pressure transducer integrated into the self diagnostic might be sufficient to provide insurance of system integrity but this would have to be confirmed In addition the system requires annual battery change This requirement would be unacceptable to the industry since a battery failure could result in a service call In order for the system to meet industry standards for reliability life and safety it probably would need to be wired into the home electrical service The need for an electrical connection adds the drawback that gas ranges could not be used in the event of a power failure 4 43 4 7 2 Prevent Unattended Cooking Warning and Control Motion sensor only Tech Class 10 Motion Power sensor Tech Class 12 Warning Only Motion Sensor only Tech Class 14 Description Overview These three approaches use a motion sensor to detect the presence of a person near an operating range The systems use warnings or warnings and control to require the cooking process to be attended These three related approaches will be evaluated as a set of technologies Technology Class 10 uses a motion sensor to detect the presence of a person near the range the lac
138. rmance and reliability tests on used and new burner and components using soil build up oxidation water and grease baked on or burnt on food materials use food mixture shown in ANSI Z21 1 or AHAM ER 1 1992 Section 8 6 Sensor should detect all required safety parameters without change in calibration Depending on the type of sensor performance and reliability tests at environmental condition of Hood fan on high 250 300 CFM in 85 humidity 20 humidity and altitudes of 3000 feet For fire management system mounted on hood a Surface temperature at any point of the top building cabinet should not exceed 300C 572 F b A fuse rated 3A connected between exposed dead metal parts of cooking appliance and ground should not open For gas ranges any components shall show no degradation when shut down of range is applied Any shut down of gas valve shall allow safe restart without attention by service personnel 4 36 4 4 5 Product Classes We have used industry statistics and definitions of product classes in order to associate specific products with relevant fire mitigation technologies Gas and electric cooking products are classified into the following product categories e Free standing Ranges a stand alone cooking product with cooktop and oven e Drop in slide in Ranges a cooking product with a cooktop and oven that is designed to be built into a cabinet counter e Surface Cooking Units a cooktop that is install
139. rner is reduced to 40 output When Tpan lt 590F burner up to full selected output Specifically for gas burner Matsushita Electric Ind Corp Harman Co Ltd Energy International Inc CPSC Prototype A TC based T sensors 3 for pot bottom to determine the arrival of pre ignition cond Heater Detect preignitioniis cycled 1s on and 6s off when Tpan is between 330 360 C and when Tpan is larger than Applications of Thermopile Infrar 360 C heater turns off Specifically for electric cooktop Using IR T sensor to measure external pot temperature on a gas range Use to determine boiling point and boil dry condition by analyzing Temp gradient in Thermopile IR sensor is used to detect the side wall T of pan pot Pot side has enamel strip w known emissivity 0 9 Sensor connects to controller which adjust heat source depending on selected T set points for specific cooking modes Heat source is cycled CPSC LG Electronics Inc Bosch Siemens DIAS Angewandte Sensorik 32 JP 4080525 US 3781506 Fire prevention by the comparing the temperature gradient of the pan with pre set conditions If gradient lt preset value A then actual T is compared to preset Ta if less continue If more stop Non contact T sensor for cooking vessel specifically for induction electric cooktop NORITZ CORP General Electric Co Schenectady SYSTEM MEASURE PAN BOTTOM TEMP W CONTACT SENSOR PROCESS SIGNAL W MIC
140. s selected burner will terminate when Tpan bottom T of food scorching referenced If fry selected burner terminate when Tpb T of oil ignition HARMAN CO LTD MOTION SENSOR amp OTHER SENSOR POWER TEMP TO USES MOTION SENSOR ONLY MEASURE PAN BOTTOM TEMP W CONTACT SENSOR PROCESS SIGNAL W MICROPRO CESSOR TO DETERMINE COOKING STATE AND ACTION OF COOKTOP HAS TO SELECT COOKING MODE COOKING VESSEL TEMP TO ACTIVATE JP 6193880 US 5243172 Contact T sensor for pan bottom on a gas fired cooktop There seem to be a T limit of 270 C for cut off There is also a controlling algorithm to allow a better handling of temperature increase to the user selected cooking temperature Cook top with automatic controls The cooktop is equipped w a pot detector weight sensor and Tsensor means It also incorporate a timer When no pot is detected or Tvessel is gt Tselect heating element can be reduced turned off Timer will keep element from shuting off for temporary pot removal due to shaking or flipping food content no sensor design but logic algorithm only RINNAI CORP U S Philips Corp US 3665159 Heating System Control a Thermistor is used as Tsensor for the cooking vessel Its signal is used to control vessel T and to speed up the T rise to user selected Tvessel while avoiding overshoot of Tselect due to heat capacity of system This achieved by constantly comparing current Tvessel and Tselect and adjusting the
141. safety system e g a press of a button Low Service call or component replacement recharging necessary for the safety system to return to its ready state 4 28 Safety system s effect on cooktop s requirement to meet current safety standards UL ANSI i e need to fail safe cooking system shuts down if safety system is not working High In full compliance with standards Medium Can be easily and obviously modified to achieve compliance Low No obvious modification available to achieve compliance 4 4 Additional Considerations for Technology Evaluation There were a number of additional considerations that formed the basis of the technology screening and evaluation work These considerations are summarized in the following five sections 4 4 1 Cooking Processes We used criteria set forth by the ANSI Z21 UL 858 STP Cooking Fires Working Group to establish the cooking requirements of any range or cooktop coupled with a fire mitigation technology Specifically we used this group s list of cooking tests as a starting point for establishing the types of cooking processes that any cooking product would be required to provide These cooking processes included e Blackening meat or fish in a skillet e Stir Frying Vegetables or Meat in a Wok Boiling 1 2 and 4 quarts of water in appropriately sized sauce pans e Heating and simmering sauces in 1 and 2 quart pans e Deep fat frying repeatedly and e Canni
142. sensor engages the bottom part of the ceramic cooktop For Elec heater w glass ceramic cooktop T sensor form PTC positive T coeff sensing element It is attached to the underside of ceramic cooktop and measure T of cooking area not pot bottom directly Matsushita Housing Products U S Phillips Corporation Emerson Electric Co for Vitroceramic A wireless Tsensor consisting of an antenna piezo electric crystal and reflector is integrated to the bottom of the pot pan The sensor transmit wirelessly to the receiver beneath the ceramic top Temperature sensor for cooking hob by using a field sensor that will measure the decay of the m DC field which is a function of cooking vessel and food content The signal from the field sensor will then be used to control the electric heat source to a user pre determined temperature Gold alloy tracks for pot sensing Has transmitter amp receiver track detection by measuring ware Sensing Sygamount of electromagnetic damping on track Detect vitroceramic T around heat zone thus cooking pot by measuring specific resistance of the gold alloy track AKO Werke GmbH amp Co KG Wangen Germany AB Electrolux Sweden Cherry Elec Products US 5283412 Fire Detection w Combo Ultrasoniq wave Doppler Sensor Micro machined Water Sensor for Home Appliance A device to measure pan or content temperature during induction heating independent of cooking vess
143. silew Angewandte Sensorik _ Applications 1999 A discussion on a new development effort on a gas sensor microarray that is specifically to determine the doneness level of Institut fur Automated Cooking and Frying control steak cooking The sensor is located on the undersidse of the pan S Ehrmann J Jungst Instrumentelle Analytik Sensors and 11 using a gas sensor microarray lid i Hermann Japanese standards for domestic gas cooker Important info there Japanese Industrial Standard Gas burning is a standard that contends all gas cooktop should limit the cooking appliances for domestic use JIS S temperature of cooking oil in the cooking vessel to be below a Japanese Standards Japanese Standards 12 2103 1991 certain level iati Association NFPA 96 Standard for Ventilation Control and Fire Protection of Commercial Cooking US standards for fire protection systems for commercial cooking 13 Operations 1998 Edition appliances including in hood fire extinguishing system instalation Appendix A Complete List of Technologies A 1 DESCRIPTION OF CURRENT TECHNOLOGIES 111 IN TOTAL BOIL OVER BOIL DRY ONLY Patent Number Description No Cook modes warm simmer boil and regular Hi Med Lo settings available Use pre set Tthres then estimate time to completion amp manipulate HS amp set alarm on when time reached Company General Electric Company data with stored empirical data w fuzzy logic to
144. ssing Auto Control to Temperature Threshold Non contact Temperature Sensor No Signal Processing Mechanical Actuation Boil Dry Spill over Sensor and Control Each technology class is described and illustrated below Detect Extinguish Fire Fusible Parts Tech Class 1 The first four technology classes involve detecting the presence of a fire and activating a fire extinguishing system In the category of Detect Extinguish Fire Fusible Parts the fire extinguishing technology is activated by a fusible link located above or near the cooktop that melts in response to a cooking fire This system would respond to a surface cooking fire of any origin When the fusible part melts due to the heat generated from the cooking fire it triggers the release of fire extinguishing material onto the cooktop This trigger can be mechanical or electrical The fire extinguishing material can be liquid generally a potassium based wet chemical formulated to extinguish grease fires or powder bicarbonate of soda or other dry mixture The system can include the actuation of an alarm and or heat source cut off either gas or electric power EXTINGUISHING AGENT SPpeAY Nozze FoS AN PMERQ GAS neraet Figure 4 1 Detect Extinguish Fire Fusible Parts Detect Extinguish Fire Non optical Temperature Sensor Tech Class 2 This category differs from the one described above in the way the fire is detected Instead of a fusible mater
145. stavsasslesiaccapsasce sutocceatesvdhecevaassoanences Figure 4 10 Prevent Unattended Cooking eee eeeceseceseeeeeeeeeeceaeceeeseneeeneeeseeees Warning and Control Motion sensor only eeseeeeceeseeeseeesneeeeeeeeees Figure 4 11 Prevent Unattended Cooking Warning and Control Motion T Sensot eeeeeseeseeeeeeeereeeeseeeseeeeees Figure 4 12 Prevent Unattended Cooking Warning and Control Motion Power sensort cccccccccccccccssesesssccccccceseussescecccsseesessesecesceseeanes Figure 4 13 Prevent Unattended Cooking Warning and Control Power level Sensor timet cccceeesceccccceseececcececcccescececaesecceaseneecees Figure 4 14 Prevent Unattended Cooking Warning Only Motion sensor only Figure 4 15 Prevent Unattended Cooking Warning Only Motion Powert Figure 4 16 Prevent Unattended Cooking Warning Only Power level Sensor tiMer ccccccccccccccsssssssescsccccccsesssescsccecceseuseusesecesess Figure 4 17 Prevent Food Ignition in Pan Elec Signal Processing Select Mode or T T sensor contacts pot Figure 4 18 Prevent Food Ignition in Pan Elec Signal Processing Select Mode or T Non contact T sensor Figure 4 19 Prevent Food Ignition in Pan Elec Signal Processing Auto activation T sensor contacts pot Figure 4 20 Prevent Food Ignition in Pan Elec Signal Processing Auto a
146. t Some training and or new equipment is necessary Specialized equipment and staff expertise or licensing is necessary 4 27 6 Effectiveness in Mitigating Surface Cooking Fires Range of Fire Incident Coverage Based on existing fire data High Would address over 90 of surface cooking fires based on the categories defined in NFPA study Medium Would address between 40 90 of surface cooking fires Low Would address fewer than 40 of surface cooking fires Percent of new product sales covered by this technology High Would cover over 90 of new surface cooking products Medium Would cover between 40 90 of new surface cooking products Low Would address fewer than 40 of new surface cooking products The degree of mitigation of fires addressed High Prevents a fire from starting Medium Extinguishes Manages a fire Low Warns of a Fire Ease of System Verification High Automatically verifies proper operation Medium User can verify operation with self test mode Low Verification of operation possible by service tech Potential for False Actuation High No chance for false positive or false negative Medium Potential for false positive Low Potential for false negative Effect of Actuation on the Safety System High Safety system does not require consumer reset and this is safe Medium Users have to manually reset the
147. t protruded above the electric ring or burner grate When the pan was placed on the heating 4 32 element the temperature probe was depressed but remained in contact with the pan bottom The sensor on the gas stove used a shield around the probe to try to insulate it from the flame As the graph below shows we recorded large differences between the temperatures measured by the probes and those measured by the thermocouples we had embedded into the pan bases particularly with the electric cooktop system P Pan contents Pan bottom Sensor reading Temperature F boiling frying searing Figure 4 26 Differences between sensor readings and pan bottom amp contents temperatures Shielded Centered Probe used in the CPSC gas range prototype controller ss stainless steel pan al aluminum pan ci cast iron pan Pan contents temperatures are not shown for searing 4 33 700 al ci 600 500 E Pan contents 400 _ Pan bottom _ Sensor reading 300 Temperature F 200 100 boiling frying searing Figure 4 27 Differences between sensor readings and pan bottom amp contents Unshielded through coil probes Temperature measured is maximum of the 3 probes used on the CPSC prototype electric cooktop controller ss stainless steel pan al aluminum pan ci cas
148. t iron pan Pan contents temperatures are not shown for searing The safety systems were triggered when the measured temperatures exceeded a pre set threshold Because the probes were reading temperatures much higher than the pan bottom had actually reached this limited the pan bottom temperature to a significantly lower threshold As a result in some cases the pan did not get hot enough to produce good searing of the steak or even to allow a rolling boil This analysis provided some insights to the basis of the cooking performance of the current CPSC pre ignition control prototypes The tests and analysis also shed some light as to the engineering requirements for these types of safety systems See Appendix D for detailed plots of temperature measurements during the cooking tests 4 4 3 Fire incident statistics used We reviewed a variety of fire incident statistics in order to associate surface fire mitigation technologies with the fraction of fire incidents that potentially could be addressed by the technology The fire statistics that we reviewed included 4 34 Ten Community Study of the Behaviors and Profiles of People Involved in Residential Cooking Fires Executive Summary National Association of State Fire Marshals Cooking Fires Task Force AHAM Safe Cooking Campaign July 1996 Includes research conducted from 1995 through 1996 US Home Cooking Fire Patterns and Trends John Hall Jr Fire Analysis and Research Division Nationa
149. t temperature of cooking oil to the increase in free fatty acid content in the oil For example for canola oil held at 190C 374F and used to fry batches of french fries for four minutes three times every eight hours O hrs 32 hrs 64hrs FFA 0 01 0 46 0 96 Reference U S Patent 6 201 145 Non hydrogenated canola oil for food applications Fan Zhegong Assigned to Cargill Inc For partially hydrogenated soybean oil commonly used for commercial frying held at 360F for 15hrs and used to fry pork and chicken continuously the final FFA content was 0 69 This oil was considered to be unacceptable for further use Reference U S Patent 6 187 355 Recovery of used frying oils Akoh te al Assigned to the Georgia Research Foundation Inc In addition the USDA requires that meat and poultry products including such products as corn dogs and pork rinds be fried in oil containing no more that 2 FFA Reference Libra Technologies Inc 101 Liberty St Metuchen NJ 08840 The tests described above relate to commercial frying situations in which the level of oil use is significantly more severe than would be experienced in the home They indicate that even with heavy commercial levels of oil reuse the increase in FFA content is not sufficient to significantly lower the ignition temperature of the oil In order to verify these data ADL carried out ignition tests on used oil In these tests approximately 750ml of canola oil was heated
150. t the reliability and durability specifications outlined in Section 4 4 6 will be a significant challenge The industry has had experience many years ago with pan contact temperature sensors used in mechanical control circuits that were intended to provide fine temperature control to the cooking process As we understand from discussions with appliance manufacturers and controls suppliers the most frequent failures modes associated with the old Burner with a Brain or Thermal Eye products included e The system would respond differently when an aluminum pot was used vs a cast iron pot e Gas turndown was insufficient to meet the lowest temperature requirements e Electric elements of the time had high thermal inertia e There was inconsistent contact area between the pot and resistance coils e The sensing element was under constant abuse The first three issues are not as relevant for this safety application because fine temperature control is not required for the pre ignition controller The last two considerations which are reliability and durability issues are still relevant and would need to be addressed for this approach to be commercialized The system must operate in a difficult environment in which grease or dirt can become baked onto the sensor The system would need to operate under these conditions Potential Effectiveness of Technology to Mitigate Cooking Fires This approach has the potential to address up to 75 o
151. technology Less than 90 since downdraft installation and island installation does not require or cannot have hood installed The degree of mitigation of fires addressed Extinguish or manage a fire after it has occurred Effect of Safety System on Cooktop Performance After Actuation of System Need significant cleaning and adjustment after actuation since extinguisher material has been released on cooktop surface and fire had occurred Effect of Actuation on the Safety System Service call and component replacement necessary to refill the extinguisher material Potential for False Actuation No chance of false alarm since a significantly higher temperature than normal cooking condition needs to be detected by the temperature sensor for the system to actuates Can Operate Over product life w o failure safety factor of 2 Looks good but no data Product has been developed and sold in the market for some time Can operate within reasonably foreseeable misuse conditions durability Looks good but no data System is out of reach of user during normal cooking operation Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop will continue working even though the safety system is not on operating Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work for all models for one product t
152. tended cooking will reduce surface cooking fires Technology Development Status There is one US and one Japanese patent that describe the combination of a timer and a power level sensor to require a user to stay close to an operating range We are not aware of any commercial products using this system Potential Impact of Technology on Product Performance and Consumer Behavior This approach will have a significant effect on consumer behavior for the same reasons outlined in Section 4 7 2 The level of behavior modification required would depend on the timer interval settings for the various power levels These timer intervals would need to be defined in a way that balanced safety and operational considerations at each power level Short timer intervals may be necessary at high power levels to prevent overheating of small volumes of material but this would require frequent resetting of the timer by the cook Further analysis of tests characterizing ignition times of various foods or amounts of oil such as the study by the AHAM cooking fires working group in 1986 would be needed to develop suitable timer interval settings The impact of the system on cooking product performance is minimal for the same reasons as described in Section 4 7 2 A simple timer and power level sensor may have longer life than the motion sensor but this system would have more consumer impact With the timer the unit would provide an alarm even if the range user were n
153. tents covering temperature sensor technologies and configurations One Japanese patent covering a full detection and extinguishing system Potential Impact of Technology on Product Performance and Consumer Behavior This approach will have no effect on cooking processes cooking time consumer behavior cooktop features or cookware applicability There is a low risk for false actuation of the system and the system components add little added risk to the homeowner The fire extinguishing systems are sold to fire equipment installers There is therefore a third party involved in installing and servicing the systems Potential Effectiveness of Technology to Mitigate Cooking Fires The technology will cover almost any type of surface cooking fire whether it is attended unattended cooking materials other materials etc The technology is applicable to both 4 42 gas and electric ranges although some additional components might be required in a gas range in order to allow for safe shut off and re start There will be some situations in which hood installations are cumbersome unsightly or unacceptable These installations include some percentage of island or peninsula locations ranges with integral downdraft ventilation and some installations with space constraints cabinetry that does not allow for the installation of the fire extinguishing cylinder These situations may represent approximately 10 of all range installations One signif
154. tfolio of approaches for fire mitigation 4 40 We added one more technology class to those listed above for more detailed evaluation We added Technology Class 19 that would prevent food ignition in a pan by controlling pan temperature through a contact temperature sensor The reasons for adding this technology are A significant amount of work has been conducted on this approach to cooking fire mitigation In addition cooking products are manufactured and sold in Japan that use this approach These factors warranted a more detailed evaluation of its potential in comparison with other technologies One of the reasons that this approach did not score highly in the technology screen is that it is unlikely that the approach is applicable to electric smoothtop systems However it may be a reasonable solution for coil or gas cooktops and thus did not warrant being dismissed After analyzing the reasons that the current prototypes did not perform well we believed that there was some opportunity to improve the effectiveness and decrease the negative impact of the technology with additional development effort 4 7 Technology Evaluation 4 7 1 Detect and Extinguish Surface Cooking Fires Fusible Link or Temperature Sensor for Fire Detection We have combined two technology classes 1 and 2 into one evaluation because of the similarities of the two approaches Description Overview As described in Section 4 2 this technology is a ful
155. tion sensor detects the presence of a user near the cooktop The location of the motion sensor may vary but most patents show the sensor on the front panel of the cooktop When the cooktop is operating the sensor will monitor presence of user If no user is detected after certain time period an alarm will sound The alarm will shut off automatically if a person is detected nearby ALAM Monon PETE STOR I l l l ae eee secs be J ALARM ENDS IF NO MONON DETECT Figure 4 14 Prevent Unattended Cooking Warning Only Motion sensor only 4 16 Prevent Unattended Cooking Warning Only Motion Power Tech Class 15 Again this system attempts to prevent unattended cooking through a warning alarm but no power level control In this case the safety system actuates only when a certain power level of the heat source has been surpassed e g Medium High level When it actuates the motion sensor detects the presence of a user near the cooktop When no user is detected after a pre set duration an alarm sounds The alarm shuts off automatically once the motion sensor detects the user POWER POWEE LEVEL SEN Sor ALARM Sono WHEN No Motion DeRectED gt Figure 4 15 Prevent Unattended Cooking Warning Only Motion Power 4 17 Prevent Unattended Cooking Warning Only Power Level Sensor Timer Tech Class 16 This technology to prevent unattended co
156. to actuate Effect on Cooking Time Will not affect cooking time since user needs to select boil cooking mode for system to actuate and this only actuates after boil is detected For other cooking process no manipulation is imposed on the heat source therefore no change in cooking time Effect of System on Consumer Behavior While Operating the Cooktop User will intuitively figure out how to use cooktop System control have knob setting or switch button specifically for boil cooking Limits availability or efficacy of marketed cooktop features None Ease of System Verification Need service technicians to verify system operation Safety System Maintenance User maintenance requires few additional procedures to clean up the temperature sensor regularly from grease or food soil build up Cookware Applicability Some cookware materials or shape can compromise safety system performance since the sensor will need to be in contact to the cooking vessel e g glass ceramic ware cookware with concave bottom Range of Fire Incident Coverage Based on existing fire data Will address less than 40 of cooking fire incident since it only address fire due to boil dry condition Percent of new product sales covered by this technology Will be difficult to apply on smooth top cooktop Ceran so will probably cover between 40 90 of new product sales The degree of mitigation of fires addressed Prevent only boil dry incident Effect of Safety System on Cooktop Perf
157. to hood duct Nozzle that sprays water droplet is situated inside the duct of a range hood to spray into duct an onto stove surface None User has to manually smother fire harmful mist fog to suffocate and cool fire stove Using fusible parts to activate nozzles to turn off grease fire JP 9117329 Incombustible back panel for wall cover MATSUSHITA ELEC Only contain fire from burning DUSKIN CO LTD User has to manually smother fire harmful Water is not recommended to turn off grease fire BUNKA SHUTTER CO LTD 20 JP 2045073 Water sprayed from surrounding pipe frame to cool and suppress fire After flame has subsided a metal plate covers pot automatically Water is not recommended to turn off grease fire None 21 JP 1015068 Range hood act as a fire enclosure containment unit Drops down to cover entire cooking unit manually activated None Has to manually activate sys Harmful to user 22 US 4633230 A temperature sensor is attached at the end of a 2 bar link arm that can be ad justed to contact the cooking container The temperature sensor will convert the measured cooking vessel temperature into electrical signal that will signal alarm in cases of boil over or boil dry None Very cumbersome setup Will affect cook s performance to have this arm sticking out on the way Can be harmful if it obstruct cook s movement and cause spills etc 23 Conference paper Automated Co
158. top None cook will not notice that system is actuating e Limits availability or efficacy of marketed cooktop features None e Ease of System Verification Need specialist s help or special equipment e Safety System Maintenance User maintenance requires few additional procedures to clean up the temperature sensor regularly from grease or food soil build up e Cookware Applicability Need special cookware for system to work properly Known emissivity 21 Range of Fire Incident Coverage Based on existing fire data Likely will address more than 40 of fire incident since it prevents pre ignition condition from occurring for most of the cooking process Percent of new product sales covered by this technology Can be installed to any new cooktop though more work needs to be done for the gas fired cooktop to make sure that radiation from flame will not be mistaken as pot high temperature The degree of mitigation of fires addressed Prevent cooking fire from occurring Effect of Safety System on Cooktop Performance After Actuation of System None system will prevent fire from occurring Therefore no additional cleaning or adjustment is necessary after each actuation Effect of Actuation on the Safety System None system automatically resets itself Potential for False Actuation Potential for false negative if sensor is dirty or illegal cookware with unknown emissivity is used Can Operate Over product life w o failure safety factor of 2
159. urability Looks good but no data Sensor is away from user s reach Safety system s effect on cooktop s conformity with current safety standards UL ANSD Need to fail safe cooking system shut down Cooktop wills still work even though the safety system is not operating off Safety system components might pose added risk to consumer None is expected Applicability across product types and product models Can work for all models of one product type for electric cooktops for vented or non vented hood and under cabinet hood or free standing ones but will not be applicable for gas cooktop since the open fire from the burner can be mistaken as cooking fire Components system availability Needs to be developed and manufactured or adapted from other industries Installation Need additional tradesmen or technician to install Serviceability Need special equipment and staff expertise or licensing to perform servicing DETECT EXTINGUISH FIRE SMOKE T SENSOR Effect on Cooking Process Will negatively affect high temperature cooking with high particulate emission such as searing or stir frying Effect on Cooking Time None Effect of System on Consumer Behavior While Operating the Cooktop User will intuitively figure out that cooktop will sound alarm whenever excessive amount of smoke is produced increasingly during cooking Limits availability or efficacy of marketed cooktop features None Ease of System Verification Need a specialist s
160. ure 4 6 Detect Fire Warning Only Optical T sensor Detect Fire Warning Only Smoke Sensor Tech Class 7 In this fire warning system a smoke sensor located near the cooktop can detect the on set of certain cooking fires particularly those involving oil grease or fat that generate large amounts of smoke prior to igniting The smoke sensor triggers an alarm when smoke levels exceed a threshold level ALARM t 7 AAT Ar N 4 j L SMOE nme L gt a P i ALARM SMOKE gt THRESHOLD rv Figure 4 7 Detect Fire Warning Only Smoke Sensor Contain Manage Fire Passive Tech Class 8 Three fire resistant panels are permanently attached to the sides and back of the cooktop The panels are intended to contain a fire from spreading to any walls surrounding the cooktop or any flammable products or materials stored nearby the cooktop ARE CONTRINMENT PACES Figure 4 8 Contain Manage Fire Passive 4 10 Contain Manage Fire Active Tech Class 9 This concept defines an active system that completely surrounds the cooktop in case of fire The system is activated when the temperature above the cooktop is higher than a threshold level In one configuration the fire resistant enclosure is in the form of a hood that drops to the cooking surface to contain the fire A provision to turn off the heat source is also possible Moves Aree FESICTANT EBNcL
161. vailability or efficacy of marketed cooktop features High New user will not notice any difference in product features Medium New user will notice difference s in product features Low Desirable product features are eliminated Safety System Maintenance High System maintenance procedure is the same as a conventional cooktop Medium System maintenance requires few additional procedures parts that do not require specialist s help Low System maintenance requires significant additional procedures parts that might require specialist s help Cookware Applicability High System works with any utensils and at normal environment Medium Some restrictions on cookware or environment Low Specific set of applicable tools utensils are needed Effect of Safety System on Cooktop Performance After Actuation of System High Cooktop can perform normally as before safety actuation Medium Minor adjustment or cleaning necessary to return it to nominal operation Low Significant adjustment or cleaning or service call necessary 3 Reliability Durability Can operate over product life w o failure safety factor of 2 Considers normal cooktop cleaning or non cleaning and maintenance High Meets targets Life data available conducted Medium Looks good but no data Low Looks problematic no data Can operate within reasonably foreseeable misuse conditions durabil
162. wn Cooktop will continue working normally if side walls were taken down by user Safety system components might pose added risk to consumer Long cooking vessel handle will jut out of the front and can risk user accidentally shoving the hot pot and content off of cooktop When front burners are on can risk burn of user s arm when reaching the food cooking vessels at the back burners Applicability across product types and product models Almost everything except island versions Components system availability Easily available parts off the shelves Installation Need additional installation effort procedures for the side walls Serviceability No new training or new equipment is necessary for servicing the walls ee FIRE ACTIVE Effect on Cooking Process None only actuates when fire has already occuring Effect on Cooking Time None only actuates when fire has already occuring Effect of System on Consumer Behavior While Operating the Cooktop None only actuates when fire has already occuring Limits availability or efficacy of marketed cooktop features None only actuates when fire has already occuring Ease of System Verification Need professional help to verify system operability Safety System Maintenance Requires significant additional maintenance procedure and specialist s help with the drop hood release mechanism and temperature sensor Cookware Applicability All cookware can be used with cooktop at any normal environment 10
163. y A self check could potentially be built into the electronics however The technology as envisioned would be fail safe because the range would not operate without the circuit in place and operating One significant issue with the motion sensor technology is that in its current configuration there is potential for false actuation For example a large pet or child could trigger the motion sensor The range operation would be enabled even if no one were attending to the cooking process Development Needs and Issues The primary development need for this technology would be to obtain some consumer feedback on the acceptability of the general approach This technology is intended to change consumer behavior It is important to understand how consumers would respond to this requirement Would a warning be effective or would it be ignored Would consumers be significantly hindered by the inability to leave the room for extended periods of time during certain cooking processes Would people develop approaches to trick the systems The industry will not accept any system that could bypass the operation of the safety system Beyond this broad consumer issue there are questions of sensor and electronics reliability and life that need to be confirmed Finally an approach to detecting the power level setting on a gas range would need to be developed We can envision a number of simple approaches to detecting knob position The technical appro
164. y the local fire station Cylinders that are installed in a residential application need to be hydro statically tested every 12 years Batteries for the electronics may need to be changes annually If the system is installed in any sort of public building it usually needs to be checked once a year by the local fire marshal or approved fire inspector Technology Development Status Products or technologies triggered by a fusible link include the Ansul Systems manufactured by Reliable Fire Equipment typically used in commercial cooking applications The Safety Gourmet manufactured by PEMALL marketed for residential applications The Guardian Systems I manufactured by 21 Century International Fire Equipment and Services Corporation with over 45 000 units installed primarily in military housing 6US patents covering various elements of extinguishing agents extinguishing configurations actuators and detectors Additional products were considered but eliminated from this category including Stove Top Fire Stop because it is not approved for use with deep fat frying Fire Breaker Fuel Neutralizer because no information was available about this product Products or technologies triggered by a non optical temperature sensor include The Guardian System II manufactured by 21 Century International Fire Equipment and Services Corporation this is an electronic control version of the Guardian I system Five US pa
165. ype for vented or non vented hood and under cabinet hood or free standing ones but will not work for non hood installation such as downdraft or island installation Components system availability Most parts have been developed but has not been manufactured in high volume at low cost Installation Needs additional tradesmen technicians to install system Serviceability Servicing the the electronics and temperature sensors require specialized equipment and staff expertise or licensing Need specialist s help to refill extinguisher canister DETECT EXTINGUISH FIRE OPTICAL T SENSOR Effect on Cooking Process None safety system only actuates when a fire had already occurred Effect on Cooking Time None safety system only actuates when a fire had already occurred Effect of System on Consumer Behavior While Operating the Cooktop None Limits availability or efficacy of marketed cooktop features None Ease of System Verification Needs service technician s help to verify system s operation Safety System Maintenance Needs significant additional procedure to clean the optical sensor change battery recharge the extinguisher material Cookware Applicability Dependent on location of of sensor it can mistake gas flame from burner or radiant heating element as fire condition Cooking using small pot pans where a radiant heat source is not fully shielded from the view of the sensor might affect system Range of Fire Incident Coverage Bas

Technical, Practical and Manufacturing Feasibility of Technologies

Contents

Download Pdf Manuals

Related Search

Related Contents