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Module 6: Detection Devices - International Association of Fire

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1. Student Text 6 60 Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Using Detection Devices It is essential that team members understand how to use the information obtained from detection devices This means you must understand the operation limitations and proper application of each device Apply the following basic rules 1 Prioritize your monitoring Generally measure oxygen levels first If oxygen is less than 21 a toxic chemical may be replacing part of the air If the oxygen is higher than 21 the enriched atmosphere may be flammable 2 Select the appropriate instrument Never use a device that cannot detect the substance or measure the concentration you believe is present Also be sure your instrument operates properly under existing conditions For example an odor of gasoline is reported in a sanitary sewer The primary hazard is explosive vapor build up within the sewer system The appropriate instru ment for measuring the hazard is the LEL CGI prefer ably a combination meter that also detects oxygen defi ciency It would be inappropriate to call for just a carbon monoxide or hydrogen sulfide sensor It would also be inappropriate to use a CGI that measures in ppm equiva lents Further if the oxygen sensor shows a concentration of less than 10 oxygen within the sewer the CGI will not operate properly The
2. llli DETECTOR CHAMBER 2 flame arrestors sidepack assembly sample hose umbilical cord amp readout assembly 6 54 pressure indicator sample pump sample flow indicator rate ind Salve filter and flow restrictor refill fitting lt lt sample in particle filter pick up fixture Organic Vapor Analyzer Instrument Operation The theory underlying the operation of FIDs is similar to that of PIDs Organic gases and vapors are burned in a flame producing carbon ions The sample of air is drawn into the probe and pumped to the detector chamber by an internal pumping system Inside the detector chamber the sample is exposed to a hydrogen flame and burned A small cylinder of hydrogen in the instrument serves as fuel for the detector The slightly positive carbon ions are attracted to a grid within the detector The ions are col lected and an electrical current proportional to the hydro Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials carbon concentration is generated The charge is amplified and displayed as a ppm equivalent The meter needle deflects higher when more vapor or gas is present in the sample The purity of the fuel supply is very important Insist on fuel with less than 1 ppm total hydrocarbon contamination THC Hydrocarbons present in fuel will be burned and measured by the FID produc
3. Student Text 6 22 Sensitivity is the ability of an instrument to detect a hazard Highly sensitive instruments can detect minute amounts Selectivity is the ability of an instrument to detect a spe cific hazard by focusing on that hazard alone through the use of selective membranes or chemistry Precise and Accurate Data Precise but Inaccurate Data Interpreting Readings Accurately evaluating a meter reading is extremely impor tant It is all too easy to read a meter at face value and move on to the next objective In addition to the consider ations discussed above consider the following when inter preting a meter reading Is the appropriate instrument being used to assess the hazard e Was the instrument reading representative of a properly operating instrument Was it fully charged accurately calibrated and free of contaminants e Does the instrument calibration still check out after readings are taken e the contaminant known or unknown How sensitive is the instrument to the contaminant being monitored Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials 5 there a conversion factor or relative response factor for the contaminant Are there any interferences e Are environmental conditions affecting responses 5 the information required to evaluate the reading available e Are the meter scale units ppm percent or counts per
4. known contaminant it is important to remember that several chemicals may mimic the reaction of the calibrant with the tube The tube reading is still valuable however since it indicates that a similar material is present As previously mentioned an unexpected color change may indicate that another type of contaminant is present In many cases a negative response from a detector tube is more informative since it can exclude a number of potential chemical contaminants No color change in a petroleum hydrocarbon tube for example indicates that no significant 6 41 IAFF Training for Hazardous Materials Student Text concentrations of gasoline light fuel oils diesel naphtha kerosene aromatic hydrocarbon solvents or other similar hydrocarbons are present It may be necessary to use more than one tube to determine the presence or absence of suspected contaminants Kits offering a decision matrix for identifying unknowns are available Questions Briefly summarize the characteristics of detector tubes Type of atmosphere Method of detection Calibration standard Check standard Range of detection Response time Power source Operating temperatures Key limitations Activities 6 42 Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Radiation Survey Meters At a
5. 10 pump strokes may have a range of 5 70 ppm Explain that different versions of detector tubes for the same chemical may be designed for different ranges in air Questions 1 Why do detector tubes have different ranges 2 Will a given detector tube detect any chemical other than the one it is designed for Module 6 Detection Devices 6 91 IAFF Training for Hazardous Materials Technician Student Text 6 92 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Detection Activity 5C Instructor Notes Demonstrate the detection range of your radiation survey meter List the following numbers on the board as a comparison 300 000 mrem LD5o 25 000 to 100 000 maximum recommended one time dose for lifesaving purposes 8 000 mrem year average annual dose a smoker exposes himself to 5 000 mrem year maximum allowable annual dose for a monitored radiation worker 180 mrem year average annual dose by U S citizen 2 mrem hour typical exposure rate used to cordon off a spill area 0 01 0 02 mrem hour average background radiation reading Question Does your radiation survey meter detect background radiation Module 6 Detection Devices 6 93 IAFF Training for Hazardous Materials Technician Student Text 6 94 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Detection Activity 5D Instructor Notes Demonstrate the detection range sens
6. Technician Appendix C Detection Levels Module 6 Detection Devices 6 133 IAFF Training for Hazardous Materials Technician Student Text 6 134 Module 6 Detection Devices Student Text Odor Green and Sweet Pungent Fruity Vinegar Fingernail Polish Remover Acrid Sharp Strong Garlic Coffee Sharp Pungent Unpleasant Putrid Benzene Unpleasant Strong Sour Ammonia like Putrid Decaying Flesh Pumpkins foul Pungent Suffocating Medicinal Phenolic Skunklike Fishy Fishy Putrid Fishy Decayed Vegetables Beer Gin Vodka Decayed Cabbage Ammonia Rotten Eggs Fecal Nauseating Aldehyde alcohol Sweet Garbage Solvent Decaying Cabbage Putrid Fishy Irritating above 2 ppm Chloroseptic Library Paste Unpleasant Putrid Nauseating Disagreeable Irritating Fecal Nauseating Boat Resin Pungent Irritating Skunklike Unpleasant Skunklike Rancid Putrid Garlic like Airplane Glue Ammonia Fishy Elmers Glue Sweet Plastic Water IPA IAFF Training for Hazardous Materials Detection Levels Material Acetaldehyde Acetaldehyde Acetic Acid Acetone Acrylic Acid Allyl Mercaptan Ammonia Mercaptan Benzene Benzyl Mercapatan Butylamine Cadaverine Carbon Disulfide Chlorine Chlorophenol Crotyl Mercaptan Dibutylamine Diisolpropylamine Dimenthyl Sulfide Diphenyl Sulfide Ethanol Ethyl Mercaptan Ethylamine Hydrogen Sulfide Indole Methanol Methyl Ethyl Ketone Methyl Mercaptan Met
7. minute e 5 the range scale factor x1 x10 or x100 e Did the meter give a stable or erratic response Each of these factors can impact the instrument reading The goal is to be sure that the reading is valid and repre sents the area that was monitored Module 6 Detection Devices 6 23 IAFF Training for Hazardous Materials Student Text 6 24 Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Combustible Gas Indicators It is essential to be able to recognize flammable or explo sive atmospheres It is just as important to be able to anticipate the potential for such an atmosphere This can be accomplished using a combustible gas indicator or CGI CGIs also referred to as explosive meters or explosimeters are used to test atmospheres that may contain a sufficient level of combustible vapors to cause an explosion lower explosive limit or LEL or support com bustion lower flammable limit The CGI is an essential piece of equipment for emergency response There are three different scales used on various CGI mod els ppm LEL or gas The most common is the LEL meter Its scale is 0 100 of LEL not 0 100 of the flammable vapor or gas in air For example if a meter reading is 50 LEL then it is indicating that 50 of the flammable vapor necessary to support combustion is present If the LEL of
8. Equipment Module 6 Detection Devices 6 129 IAFF Training for Hazardous Materials Technician Student Text 6 130 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Manufacturers and Suppliers of Detection Equipment AIM USA P O Box 720540 Houston TX 77272 0540 713 240 5020 Bacharach Instrument Co 625 Alpha Drive Pittsburgh PA 15239 412 963 2000 Bicron Corporation 12345 Kinsman Road Newbury OH 44065 216 564 2251 CEA Instruments Inc P O Box 303 Emerson NJ 07630 201 967 5660 Detector Electronics Inc 6901 West 110th Street Minneapolis MN 55438 800 765 FIRE 612 941 5665 Dynamation Inc 3784 Plaza Drive Ann Arbor MI 48108 313 769 0573 Eberline Instrument Corp P O Box 2108 Santa Fe NM 87504 2108 800 678 7088 or 505 471 3232 Enmet Corporation P O Box 979 Ann Arbor MI 48106 0979 313 761 1270 The Foxboro Company Environmental Monitoring Operations P O Box 500 East Bridgewater MA 02333 800 321 0322 or 508 378 5400 GasTech Inc 8445 Central Avenue Newark CA 94560 3431 510 794 6200 Grace Industries P O Box 167 Transfer PA 16154 800 969 6933 or 412 962 9231 Heath Consultants 100 Tosca Drive P O Box CS 200 Stoughton MA 02072 617 344 1400 HNU Systems Inc 160 Charlemont Street Newton MA 02161 800 527 4566 or 617 964 6690 Module 6 Detection Devices 6 131 IAFF Training for Haz
9. Materials Carbon Monoxide CO and Hydrogen Sulfide H S Meters There are detectors similar to oxygen meters that are designed to provide accurate responses to specific gases Some combination meters meters with more than one detector are referred to as multigas or toxic gas meters Many CGI O can be equipped with additional sensors Most instruments equipped with the additional detector are calibrated for carbon monoxide or hydrogen sulfide both of which are toxic at low concentrations Both of these instruments utilize a detector that operates by chemical reaction with the gas Like the oxygen meter these meters are subject to interference from other gases or vapors They are also affected by environmental conditions such as temperature and barometric pressure When using these meters operating instructions must be reviewed carefully Sensors must be calibrated and replaced periodi cally Solid State Sensors Solid state sensors are found in some newer CGIs and a few chemical specific instruments These sensors are typically semiconductors coated with metal oxide compounds and heated to provide stability Different oxides are used to detect different target gases Solid state sensors are some times called metal oxide sensors Depending on their proprietary manufacturing method these sensors can react quickly and with extreme sensitiv ity Among other advantages they require less oxygen f
10. Review the steps that should be taken for a proper field check for each instrument your hazardous materials team carries Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Propane Case Study Activity 4 In 1987 a firefighter hazardous materials team responded at 2 00 a m on a calm cool night to a leaking one ton propane tank on top of a building The tank was accidentally damaged as it was being positioned by a construction crane The crane operator s assistant who was on top of the building was injured The tank was oriented in a position that allowed propane to flow onto the surrounding ground near the crane Due to terrain responders were forced to approach the building from the side opposite the crane Immediately after the accident the crane was shut off The first in units were focused on rescuing and treating the injured crane operator s assistant The hazardous materials team was called in to assess the hazard of the propane tank The hazardous materials team instrument operator began monitoring the area using a CGI O meter and wearing SCBA and turnout gear No propane was detected despite the obvious dam age to an outlet pipe on the propane tank Hazardous materials team members believed that the leaking propane had auto refrigerated the tank and the propane leak had sealed itself with ice in the process Instrument readings confirmed this and the haz mat team began plans to restart the crane
11. Text 6 116 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Radiation Survey Meter Activity 12B Instructor Notes Divide the class into groups of two or three to conduct the exercise Each participant must have the opportunity to use the meters available You will need the following materials Radiation detection instruments with a variety of probes used by your department Radiation sources alpha beta gamma Sources be obtained from a variety of vendors including The Nucleus Inc Oak Ridge TN 615 483 0008 The sources are license exempt quantities maximum quantity is 0 Shielding notebooks aluminum foil fire fighting clothing etc Rulers 12 inch or longer Instruct the participants that the radiation sources are very small amounts and will not result in significant radiation exposure when used properly Refer to manufacturer s information for more details Observe participants as they use a variety of probes for each of the sources Encourage them to experiment with shielding while measuring various types of radiation Remind partici pants of the importance of recording background radiation Questions 1 Which instrument s is are the most sensitive for detecting gamma radiation Beta radiation Alpha radiation 24 How you distinguish between sources of gamma beta radiation 3 What accounts for the different exposure
12. afterward two police officers and two paramedics none wearing respiratory protec tion also enter the vault All have to be assisted out Fire fighters arrive don SCBA and remove the three remaining men from the bottom of the vault Two are found face down in the water the third is in a sitting position The contractor and supervisor are pronounced dead on arrival at a local hospital The maintenance worker is hospitalized Tests of the atmosphere at the bottom of the vault reveal the following O 796 CO more than 3 LEL negative H S negative State investigators conclude that an algae bloom and bacterial action in the water resulted in 096 free oxygen in the water Carbon dioxide a waste product was liberated and displaced much of the oxygen in the vault Questions 1 What hazards were present in the vault 2 Which detection devices can be used to assess atmospheres like that in the vault Module 6 Detection Devices 6 81 IAFF Training for Hazardous Materials Technician Student Text 6 82 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Operational Checks Demonstration Activity 2 Instructor Notes Show the operation manual for each instrument and discuss where they are stored Explain that it is important to review the manuals because they contain information on minimum recom mended voltages and the meanings of error messages Cover the key points as discussed below 1
13. and limiting factors associated NFPA 472 4 2 1 3 4 1910 120 6 iii B with the selection and use of the following monitoring equipment test strips and reagents to include but not limited to operation calibration response time detec tion range relative response sensitivity selectivity inherent safety environmental conditions and nature of hazard Carbon monoxide meters Colorimetric tubes Combustible gas meters Oxygen meter Passive dosimeter Photoionization detector pH indicator and or pH meters Radiation detection instruments Reagents Test strips Given three hazardous materials one of which is a solid one a liquid and one a gas and the following monitor ing equipment test strips and reagents select the appropriate equipment and demonstrate the proper techniques to identify and quantify the materials For example the techniques for the use of air monitor ing equipment should include monitoring for lighter than air gases in a confined area heavier than air gases and vapors in a confined area and heavier than air gases and vapors in an unconfined area NFPA 472 4 1 1 3 5 1910 120 6 iii B Demonstrate the field maintenance and testing proce dures for the monitoring 4724 2 1 3 6 1910 120 6 iii 6 4 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Instructor Preparation Module 6 Detection Device
14. checking a tube will allow you to become familiar with the color you might expect to see Alarms Check that the alarms audio and visual sound at the appropriate set points e Readouts Show the students the digital or analog readout on your instrument The type of readout selected is a matter of personal preference Digital readouts are sometimes easier to read while analog readouts most often show trends increasing or decreasing levels The type of readout the instrument has is less important than most other instrument factors Module 6 Detection Devices 6 85 IAFF Training for Hazardous Materials Technician Student Text 6 86 Pump Demonstrate how the pump works on the instrument Show how to check that the hoses are properly connected and that the instrument is actually drawing a sample from the end of the hose not from a leaking connection midstream Many manufacturers recommend placing a finger over the end of the hose for a second or two If the pump starts to labor the sample is properly entering the instrument Parts Show the students all the available parts for your instrument Many instruments come with external filters probes earpieces chargers calibration kits manuals spare filters custom cases etc Directions Again highlight the importance of following the manufacturers instructions Let the students know that a telephone number for the manufacturer is in the manual if they need technical assistance
15. must be manufactured and certified to be safe for such use An instrument marked as UL or FM approved as intrinsically safe for Class 1 Division 1 Groups ABCD is safe for use in flammable atmospheres The National Electrical Code defines Divisions as fol lows Division 1 An area where a leak is or may occur at any time Division 2 An area of sealed containers where a leak would occur only if a container ruptured or otherwise failed Groups refer to specific gases or vapors that may be encountered Group A Acetylene Group B 1 3 butadiene ethylene oxide hydrogen Group C Acetaldehyde carbon monoxide cyclopro pane diethyl ether ethylene hydrogen sulfide hydra zine methyl ether NEC markings should be found on combustible gas indica tors because spills of flammable liquids or leaking flam mable gases may result in flammable or explosive atmo spheres An intrinsically safe instrument should be used whenever the atmosphere is potentially flammable Intrinsically safe instruments are certified as such by the manufacturer or a third party Instruments labeled Explo sion proof are generally stationary devices any explosions are contained within enclosures Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Instruments approved as non incendive for Class 1 Division 2 Groups ABCD are approve
16. of this is a CGI calibrated to methane used to test for a natural gas leak If the meter reads 0 5 or 50 depending on the type of readout this means that 5096 of the concentration of methane needed to reach an explosive environment is present Since the LEL for methane is 5 3 methane in air the meter indicates that a 2 65 or 26 500 ppm concen tration of methane is present Response curves such as the one shown below and con version factors can be used to determine the actual LEL present if the identity of the material is known When using response factors multiply the readout in LEL by the factor to obtain the actual LEL present For example if a CGI calibrated to pentane is used to measure an environment containing methane multiply the instru ment reading by a response factor If the response factor for methane is 0 6 for this instrument the meter reading must be multiplied by 0 6 A meter reading of 50 LEL would correspond to an actual LEL for methane of 30 6 29 IAFF Training for Hazardous Materials Student Text Questions If this same instrument had a reading of 40 LEL what would the actual LEL be for methane 2 different instrument calibrated to pentane had a response factor of 0 5 for methane and a reading of 7096 LEL what would the actual LEL be for methane If a concentration greater than the LEL and lower than the UEL is present the meter needle or digital reado
17. the device Also calibration checks help assess the effects of temperature humidity barometric pressure and related environmental conditions Perform instrument calibration checks under the same environmental conditions in which the instrument will be used such as a safe area near the incident to be investigated Finally remember that high voltage and static can affect the needle display on some instruments All of these factors should be considered when operating any of the instruments discussed in this unit Validity of Measurements When evaluating detection devices manufacturers may use a variety of terms to describe the instrument s ability to respond accurately and consistently to the materials it is designed to detect Commonly used terms are accuracy precision and sensitivity and selectivity Accuracy is a measure of data quality and its relationship to some true value An accurate reading results when the average of all measurements falls within an acceptable predetermined interval from the true value typically within 5 to 10 Precision is the grouping of separate readings around a calculated average Instruments should respond in a consis tent manner Another term for this is reliability Measure ments can be inaccurate and still be reliable so simply obtaining the same reading more than once does not guar antee that the reading is accurate 6 21 IAFF Training for Hazardous Materials
18. the gas is 2 then the CGI is indicating that there is one half 50 of LEL or 1 gas present If vapor concentration increases the reading will get closer to LEL Some CGIs also indicate when the concentration of combustible gas or vapor in air exceeds the upper explosive limit UEL The CGI operating instructions should be consulted prior to use for behavior at the UEL and above 6 25 IAFF Training for Hazardous Materials Student Text 6 26 Instrument Operation The CGI is able to detect gases or vapors by allowing air to diffuse into a sensor or by drawing a sample of air through its hose A hand operated or battery powered pump is used to draw the sample Combustible gases enter the instru ment diffuse through a coarse metal filter and come in contact with two hot filaments inside the sensor Both filaments are heated to the same temperature and therefore have the same resistance One filament is coated with a catalyst Combustible gases burn on this catalytic filament no combustion occurs on the uncoated filament Combus tion causes the filament with the catalyst to increase in temperature causing an increase in resistance This change in resistance causes an imbalance in the resister circuit The change in resistance across the circuit is translated into a CGI meter reading All CGI readings are relative to a calibration gas Readings correspond to the relative increase in resistance produc
19. through an electronic circuit with the results being translated to a needle deflection or digital readout Like CGIs oxygen meters are adversely affected by certain gases and vapors In particular carbon dioxide can perma nently affect meter response by interfering with the chemi cal reaction in the detector cell The result is that the meter is no longer capable of detecting oxygen As a general rule oxygen meters can be used in atmospheres greater than 0 5 5 000 ppm CO only with frequent replacement of the oxygen detector cell Atmospheres containing oxidizers can produce a false high response on the meter Like atmospheric oxygen oxidizers react in the detector resulting in a higher reading 6 33 IAFF Training for Hazardous Materials Student Text 6 34 Calibrating Oxygen sensors are affected by the same factors that affect other electrical detection devices such as humidity and temperature In addition electrochemical sensor readings are affected by altitude At higher altitudes the partial pressure of a gas decreases so a meter reading taken at a high altitude will be lower than one taken at sea level Oxygen sensors provide a good example of this There are significant changes in meter readings obtained when a meter calibrated at sea level is moved to increasing eleva tions above sea level as shown below Elevation Oxygen Reading sea level 20 9 500 feet 20 4 1 000 feet 20 1 2 000 f
20. to remove the victim from atop the building 1 How would you field check this instrument 2 Where should you monitor for propane Prior to starting the crane the hazmat team decided to double check their findings with their backup meter and found combustible levels of propane approximately 100 feet from the building from about the knee level down They plugged the leak and removed the victim working on the side of the building opposite the propane cylinder It was later discovered that no field check was done and that the instrument had an inoperative combustible gas sensor The reading at zero was inaccurate The instrument was taken out of service and repaired The department then instituted a field check procedure Module 6 Detection Devices 6 87 IAFF Training for Hazardous Materials Technician Student Text 6 88 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Detection Activity 5A Instructor Notes Demonstrate the detection range of your combustible gas indicators Combustible gas meters typically respond to either LEL or gas in air Questions 1 Your combustible gas meter is calibrated to a gas with LEL of 1 296 and it is reading 50 of the LEL of the calibration gas What is the actual concentration you are measur ing 2 Your combustible gas meter is calibrated to a gas with an LEL of 1 3 and is reading 2 6 in air of the calibration gas What is the act
21. 8 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials TechnicianO Electrochemical Sensor Activity 10 A deep underground secure storage vault was the site of an electrical failure and subsequent fire There is concern that computer tapes and microfiche stored at several levels below ground have been destroyed A combination meter gives the following readings 20 396 oxygen greater than 500 ppm carbon monoxide and 2 LEL Question Evaluate the possible hazards that may be present Module 6 Detection Devices 6 109 IAFF Training for Hazardous Materials Technician Student Text 6 110 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Detector Tube Activity 11A A sewage treatment facility has a CGI that appears to be malfunctioning The meter gives a persistent reading of 100 LEL The Draeger polytest tube and petroleum hydrocarbon tube each show no color change after the recommended maximum number of strokes Questions 1 Assuming the CGI is functioning correctly what might account for a persistent reading of 10096 LEL 2 The CGI could be detecting a flammable gas that the detector tubes cannot detect List those gases then through a process of elimination and identify the gas that is most likely present 3 What tube can be used to verify the presence of the gas detected by the CGI and give an estimate of the concentration present 4 What is the i
22. Cotton Plug on Silica Gel Detector Tube Instrument Operation The testing unit consists of an aspirating pump a detector tube and with some models a stroke counter The tips of the glass detector tube are broken off and the tube is then connected to a piston type or bellows type pump If there is an arrow on the tube it should be placed pointing toward the pump since the arrow indicates the direction of air flow 6 39 IAFF Training for Hazardous Materials Student Text 6 40 One full pump stroke draws 100 cc through the tube regardless of the manufacturer Instructions for tubes designed with piston type pumps always include the dura tion of each pump stroke Each type of tube requires a certain number of pump strokes and a minimum amount of time between strokes to assure that an adequate sample is taken If time is inadequate or an insufficient number of strokes are taken the reading will be inaccurate Manufac turers instructions provide the proper procedures to use with each tube as well as the sampling range A vapor or gas contaminant reacts with the indicator chemi cal in the tube resulting in a color change in the tube Manufacturers instructions should describe the color change that indicates a positive reaction and whether the length of the color change is proportional to the concentra tion of contaminant Detector tubes are calibrated to one material but typically respond to many other ma
23. Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Calibrating FIDs are typically factory calibrated to methane A known concentration of methane is used for calibration checks to ensure that the instrument is operating within factory calibration standards Like the photoionizer the FID has a span potentiometer In some models this is called the gas select Each manufac turer specifies the initial span potentiometer setting that should be used during the calibration check For example certain Foxboro OVA models should read the standard accurately when the gas select is set at 30 If it does not the gas select can be adjusted Questions Briefly summarize the characteristics of an FID Type of atmosphere Method of detection Calibration standard Check standard Range of detection Response time Power source Operating temperatures Key limitations Activities 6 57 IAFF Training for Hazardous Materials Student Text 6 58 Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Other Detection Methods Optional Characterization of liquids and solids requires using differ ent methods than air monitoring Real time characteriza tion can be accomplished using test kits The simplest kits use te
24. Instruments must have sufficient power 2 Always check the battery power low battery display before using the device and recharge if necessary 3 Adequate warm up time Meter zeroing Cleaning and decontamination Maintenance Module 6 Detection Devices 6 83 IAFF Training for Hazardous Materials Technician Student Text 6 84 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Calibration and Field Checks Demonstration Activity 3 Instructor Notes Explain to the students that under most field conditions readings will be estimates not exact concentrations To improve accuracy it is important to have instruments calibrated Cover the key points as described below 1 Detection devices are calibrated to a standard at the factory 2 All instruments must be checked regularly to make sure they are still responding as calibrated 3 Instrument response should be checked against the calibration standard before and after each use 4 Calibration checks should be documented 5 Field checks are mandatory Battery Check the power level and compare it to the minimum recommended voltage Sensors Challenge the sensors to be sure they actually work Oxygen sensors can be activated with exhaled breath CGI sensors can be activated with a lighter or fumes from a gas tank on a rig Radiation survey meters can be activated with check source Detector tubes cannot be reused but
25. Many radiation meters have interchangeable detectors While some detectors are specific to one type of radiation others may detect alpha beta and gamma Shielding can help in determining the type of radiation involved For 6 43 IAFF Training for Hazardous Materials Technician Student Text 6 44 example if the meter no longer detects radioactive activity when the source is covered with a sheet of paper then the source is probably emitting alpha radiation Calibrating Radiation survey meters are usually returned to the manu facturer for recalibration This is because the radioactive source used for calibration may require a license to main tain Check sources of radiation to ensure that the meter responds Interpreting Results A gamma radiation meter usually reads in milliroentgens per hour mR hr or microroentgens per hour uR hr The unit mR hr is roughly equivalent to millirem per hour mrem hr for gamma radiation These units express an exposure rate that is the amount of radiation to which an individual would be exposed at the point of measurement Beta and alpha radiation are also sometimes measured in this way Meters with a scale that reads in counts per minute cpm are typically used with alpha or beta detectors These meters are generally used to monitor for contamination Background cpm readings can be compared to readings from potentially contaminated items If these readings are higher than the backgr
26. Student Text IAFF Training for Hazardous Materials Module 6 Detection Devices Module 6 Detection Devices IAFF Training for Hazardous Materials Student Text 6 2 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Module 6 Detection Devices Module Description The purpose of this unit is to introduce participants to the detection devices commonly used by fire department hazardous materials technicians to monitor atmospheres in hazardous environ ments The unit is also intended to provide hazardous materials team members with the opportu nity for hands on practice with the instruments used in their departments Prerequisites Students should have completed a hazardous materials operations level training program Students should have completed Module 3 Health and Safety and Module 5 Practical Chemistry Module 6 Detection Devices 6 3 IAFF Training for Hazardous Materials Student Text Objectives Upon completion of this module participants will be able to Objectives NFPA Standards OSHA Standards Identify the type s of monitoring equipment test strips and reagents used to determine the following hazards NFPA 472 4 2 1 3 3 910 120 6 iii B Corrosivity pH Flammability Oxidization potential Oxygen deficiency Radioactivity Toxic levels Identify the capabilities
27. able for use in the gasoline contaminated sewer the hazard can still be assessed A detector tube can be used to measure the concentration of gasoline or petroleum hydrocarbons in the sewer Gasoline has an LEL of approximately 1 496 or 14 000 ppm a tube reading of 1 400 ppm represents 10 of the LEL of gaso line The same concept applies to other sensors A meter read ing of 20 4 oxygen indicates only a slight decrease in oxygen concentration However it also represents a signifi cant concentration of another gas or vapor that is displacing the oxygen 7 Establish Action Levels Action levels are readings or responses to knowns or unknowns that trigger some action The action taken may include evacuating the area of unprotected or unnecessary personnel watching meter readings more closely upgrad ing levels of personal protection or leaving the area alto gether These must be based on departmental Standard Operating Procedures SOPs The action levels discussed below are accepted by most agencies LEL Action Levels The LEL CGI is a safety meter it is intended to tell the user whether or not it is safe to be in a particular area A meter reading of 100 LEL is obviously unsafe But at what LEL reading should you become concerned The answer depends on whether the mate rial is a known or an unknown If the material is 6 63 IAFF Training for Hazardous Materials Student Text 6 64 kn
28. ally polymerized methyl methacrylate mixed with methanol is punctured at a facility Workers notice a small puddle of material and immediately clean it up Workers adja cent to the area begin to complain of eye and throat irritation On arrival you notice a bitter odor A PID with a 10 2 eV UV lamp is used a meter reading of 42 units is obtained in the spill area The IP of methanol is 10 8 eV the IP of methyl methacrylate is 9 7 eV The OSHA 8 hour permissible exposure limit PEL for methyl methacrylate is 10 ppm and 200 ppm for methanol Questions l Knowing the IPs of both chemicals what is one of the first points to consider before you attempt to use a PID 2 Will the PID accurately detect both chemicals Module 6 Detection Devices 6 121 IAFF Training for Hazardous Materials Technician Student Text 6 122 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician FID Activity 14A At the methanol and methyl methacrylate spill described in the PID Activity 13B a FID gives a reading of 380 units The PID gave a reading of 42 units Question 1 Why do the two meters give such different readings Module 6 Detection Devices 6 123 IAFF Training for Hazardous Materials Technician Student Text 6 124 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician FID Activity 14B Vapor Survey Meter Instructor Notes Divide the class into groups of two
29. ardous Materials Technician Student Text Industrial Scientific Corp 1001 Oakdale Road Oakdale PA 15071 800 338 3287 or 412 788 4353 Ludlum Inc P O Box 810 Sweetwater TX 79556 800 622 0828 or 915 235 5494 Lumidor Safety Products 11221 Interchange Circle Miramar FL 33025 305 625 6511 Matheson Safety Products 30 Seaview Drive Secaucus NJ 07096 1587 800 828 4313 or 201 867 4572 MDA Scientific Inc 405 Barclay Boulevard Lincolnshire IL 60069 800 323 2000 Mine Safety Appliances P O Box 426 Pittsburgh 15230 800 MSA 2222 412 967 3000 National Draeger Inc P O Box 120 Pittsburgh 15230 800 922 5518 or 412 787 8383 Neotronics P O Box 370 Gainesville 30503 0370 800 535 0606 or 404 535 0600 Photovac International Inc 25 B Jefryn Boulevard West Deer Park NY 11729 516 254 4199 Protech Safety Equipment Inc P O Box 4280 Linden NJ 07036 800 526 4121 or 908 862 1550 Scott Aviation 225 Erie Street Lancaster NY 14086 716 683 5100 S E International Inc P O Box 39 Summertown TN 38483 615 964 3561 Sensidyne Inc 16333 Bay Vista Drive Clearwater FL 34620 800 451 9444 Thermo Environmental Instruments Inc 8 West Forge Parkway Franklin MA 02038 508 520 0430 Victoreen Inc 600 Cochran Road Cleveland OH 44139 3395 216 248 9300 6 132 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials
30. be protected from contamination at incident scenes if proper precautions are taken For example you can wrap the devices in plastic or trans port them in covered containers The sensors of course must be fully exposed to air in order to work properly Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials If instruments do become contaminated by hazardous materials they must be decontaminated like any other equipment If you suspect an instrument has been contaminated leave it in the Hot Zone with other exposed equipment for later decontamination or dis posal Activity Module 6 Detection Devices 6 65 IAFF Training for Hazardous Materials Student Text 6 66 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Application Exercise Module 6 Detection Devices 6 67 IAFF Training for Hazardous Materials Student Text 6 68 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Application Exercise Instructor Notes Module 6 Detection Devices 6 69 IAFF Training for Hazardous Materials Student Text 6 70 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Application Exercise Worksheet As you practice using the instruments at the work stations yo
31. by the equipment and verify that the readouts make sense relative to other available information Activity 6 11 IAFF Training for Hazardous Materials Student Text General Considerations in Monitoring Purpose of Detection and Monitoring Equipment The first step in using monitoring and detection equipment is to define the information needed This will help deter mine the appropriate equipment and sampling strategies Desired information may include What hazard if any is present Is it dispersing or concentrating Do responders have adequate protection Is the hazard affecting surrounding areas Factors Influencing the Quality of Information Team members must be aware of various factors that can directly affect the instrument readings Some of these factors are inherent to the instrument others are determined by the environment in which the instrument is used Instrument Factors Proper equipment operation Instrument calibration and calibration checks Equipment detection range Device relative response compared to the calibra tion gas Response time Inherent safety Reliability of power source e Non Instrument Factors Nature of the hazard Location of monitoring Interferences Environmental conditions e g temperature and humidity If these factors are not addressed the readings may be improperly evaluated and result in poor decision making 6 12 Module 6 Detection De
32. cus on what is perceived to be the primary hazard of a situation and forget that other hazards may also be present Additional instruments can be used to rule out other potential hazards For example if there is 0 LEL and 20 8 oxygen in a sewer vault and a petroleum vapor tube detector tube reading of only 100 ppm then other hazards must be considered as well The vault should be assessed for the presence of other materials such as hydrogen sulfide gas using the appropriate sensor or detec tor tube 5 Useone instrument to confirm another In the sewer scenario detector tubes can be used to deter mine the concentration of gasoline present and can verify the information collected using a CGI If the CGI in the example gave a reading of 1096 LEL and use of the char coal filter as described above decreased the reading to 596 Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials LEL then half the meter reading is caused by another gas perhaps methane Detector tubes can be used to measure the actual amount of methane and gasoline present Con centration readings from each tube when added together should correspond approximately to the CGI composite response 6 Interpret Readings in More Than One Way With increasing familiarity in instrument use team mem bers will be able to use readings in other ways For ex ample if a CGI is not avail
33. d as safe for atmo spheres that are not flammable These instruments are considered safe in that they will not serve as sources of ignition for other combustible and flammable materials in the area Limit the use of such instruments to clean up activities or situations where it is certain that the atmo sphere is not explosive or flammable Not all instruments have non incendive ratings Non rated instruments should be used only with a combustible gas indicator so that you can be warned of potential flammable or explosive vapor concentrations Sampling Techniques When entering an unknown atmosphere to conduct air monitoring remember the fundamental physical properties of hazardous materials Most gases and vapors will tend to sink in air but some will rise Good monitoring technique involves sampling enough locations to ensure that you have searched effectively for the hazard your instrument is designed to detect If the chemical you are monitoring for tends to rise in air such as methane or anhydrous ammonia begin sampling with the sensor held high moving lower as you proceed If the chemical tends to be heavier than air hold the sensor low at first then sample higher areas as you proceed Be sure to sample slowly enough so that the instrument has time to draw the sample in and produce a readout before you move to another location Most instruments with integrated pumps require one to two seconds per foot of sample line For exam
34. ed by the calibration gas when it burns on the catalytic fila ment When measuring another gas or vapor the instru ment still responds to the increased temperature of the filament However some vapors and gases produce more heat when burned These hot burning gases cause the catalytic filament to become hotter at lower concentrations than the calibration gas Conversely some gases burn cooler than the calibration gas and a higher concentration of such a gas is needed to cause the same increase in fila ment temperature Some combustible gas indicators are equipped with infrared IR capability IR monitors are used on CGIs to detect the presence of higher levels of carbon dioxide and methane in concentrations greater than 5 000 ppm Response curves or conversion factors indicate the gases that burn hotter or cooler than the calibration gas Hot burning gases will result in readings that indicate higher concentrations than actually exist These gases appear on the left side of the calibration response curve and have conversion factors of less than 1 Cool burning gases appear to the right side of the response curve and have conversion factors greater than 1 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials The figure below demonstrates response curves for three materials The calibration gas is pentane Methane burns hotter than pentane so the meter reading is at 10096 LEL whe
35. eet 19 3 4 000 feet 18 0 6 000 feet 17 3 8 000 feet 15 4 10 000 feet 14 3 It is essential that you adjust these devices to background gases at the same altitude as the atmosphere to be tested Testing a detector at the station then using it at a different elevation will probably result in an inaccurate reading Question Why will an oxygen meter calibrated at sea level indicate an oxygen deficient atmosphere at high altitudes Clean ambient air can be used for calibrating an oxygen sensor given that ambient air should contain 20 996 oxygen There are also oxygen deficient check gases available These are often used in combination with a CGI calibration gas for use in calibration checks of combination meters Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Interpreting Results There may be several reasons for low oxygen levels in ambient atmospheres Oxygen may be in the process of being displaced by a flammable toxic or other hazardous gas or vapor A low reading may also suggest that there is a chemical reaction taking place that is consuming the oxy gen Questions 1 Air is primarily made up of what gases and at what percent 2 If you replace 5 50 000 ppm of the total volume of air in a confined space with a toxic or flammable mate rial how much oxygen will you have replaced Occupational Safety and Health Administration
36. ents or ppm benzene equivalents Many materials are not ionized as well as the factory calibration gas while a few are ionized more easily In general consider the meter reading as only an indication of the presence of contaminants and remember that the actual ppm concentration is probably higher than the meter read ing Readings of 5 ppm or more of an unknown gas or vapor may indicate the need for protective clothing and breathing apparatus While PIDs can detect many materials at low ppm concen trations that are not detectable by CGIs they do not detect everything The absence of a meter response does not mean that there are no contaminants present It simply indicates that the instrument does not detect the presence of certain vapors or gases 6 51 IAFF Training for Hazardous Materials Student Text 6 52 Questions Briefly summarize the characteristics of a PID Type of atmosphere Method of detection Calibration standard Check standard Range of detection Response time Power source Operating temperatures Key limitations Activities Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Flame lonization Detectors Organic Vapor Analyzers Optional Flame ionization detectors FIDs are versatile monitoring instruments Depending on the model this instr
37. es will increase Observe participants conducting leak tests prior to sampling After participants have used the tubes appropriate to the contaminants encourage them to experiment to observe different re sponses For example have the students sample toluene with an acetone tube Discuss possible interferences according to manufacturer s information Questions 1 Did you have any difficulty reading the tubes Were there interferences 3 What color change did you observe in each of the tubes 4 What chemical reaction was taking place Module 6 Detection Devices 6 113 IAFF Training for Hazardous Materials Technician Student Text 6 114 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials TechnicianO Radiation Meter Activity 12A You arrive at the scene of a radiation incident Radiation levels are between 1 5 and 3 mR hour Using the detection instrument s available in your department answer the following questions Questions 1 What is the operating range of your instruments Is it designed to detect these levels 2 What type of radiation does your instrument s detect 3 Does your equipment have a shield How would you use it in this incident 4 If you are standing 100 feet away from the source and your instrument is reading 1 5 to 3 mR hour what type of radiation are you detecting Module 6 Detection Devices 6 115 IAFF Training for Hazardous Materials Technician Student
38. esponding reading on your meter applying the appropriate response factors Module 6 Detection Devices 6 103 IAFF Training for Hazardous Materials Technician Student Text 6 104 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician CGI Activity 8C At a cosmetic manufacturing facility a worker who entered an ethyl acetate storage tank to remove residual liquid and sludge has collapsed inside the tank A coworker who attempted a rescue has also been overcome and is lying unconscious in the tank On arrival fire fighters lower a sample line into the tank and note the following readings from a CGI meter 9096 LEL at the level of the victims 55 LEL at mid tank 40 LEL at the top of the tank The LEL of ethyl acetate is 2 Question 1 The approximate down time of victims prior to fire department arrival is 20 minutes What information would be valuable in determining the likelihood of victim survival Module 6 Detection Devices 6 105 IAFF Training for Hazardous Materials Technician Student Text 6 106 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician CGI O Activity 9 Instructor Notes Divide the class into groups of two or three to conduct the exercise Each participant must have the opportunity to use each instrument You will need the following materials CGI meter Check gas for each CGI 3 beach balls Flammable liquid
39. etected efficiently How well a chemical ionized is a function of its molecular chemistry including electron orbits electron sharing and the type of molecule Relative response factors can be applied to help quantify unknown chemicals 6 49 IAFF Training for Hazardous Materials Student Text 6 50 Calibrating Photoionizers are usually calibrated to benzene at the factory though isobutylene is also used A photoionizer cannot discriminate between different vapors and gases the response it generates is based on its response to the factory calibrant Consequently its response may be higher or lower than the true concentration depending on the relative response of the detector to the contaminant Calibration of a photoionizer is not usually checked against a benzene standard due to the health hazards associated with benzene Instead a check gas or span gas of a known ppm concentration is used to determine whether the instru ment is still within factory calibration limits The instru ment should detect the check gas at the correct level when it is properly calibrated Some PID manufacturers supply check gas information regarding the correct instrument settings and the ppm readout that should be obtained Some instruments MicroTIP Photon OVM have micro processors that use an internal calibration program The instrument prompts the user through each step of the cali bration procedure Instruments tha
40. ffect detector tubes This includes light especially ultraviolet light Tubes should be left in their original boxes until used The aspiration pump must be checked for leaks prior to sampling Instructions for leak checks will vary depending on the manufacturer Often a leak check is done by insert ing an unbroken detector tube into the pump orifice and attempting to aspirate air through the pump If any air is drawn in there is a leak in the pump Any leaks must be repaired prior to use Also the pump must be volumetri cally calibrated on a quarterly basis to check the volume of air that is drawn with each pump stroke Interpreting Results The detector tube is read by noting the number on the tube that corresponds to the point at which the color change ends Often this is a jagged or faded edge making it difficult to judge exactly where the color change ends This can make it difficult to get accurate results from this seem ingly simple test Because the endpoint of discoloration in a tube is usually not definitive it is helpful to standardize the practice for reading and interpreting tubes Also manufacturers information should be consulted to deter mine the tube s range of accuracy In an emergency situa tion it may be prudent to use the highest reading In any case it is easier to read the tube by comparing an exposed tube to an unbroken tube of the same type If the tube is being used in an environment with an un
41. grade the oxygen sensor The manufacturer of your meter should provide information on how the service life of your oxygen sensor is decreased by varying levels of CO Also certain vapors and gases can cause a detector tube to produce an inaccurate response Manufacturers supply information about interferences for each specific tube this information 6 19 IAFF Training for Hazardous Materials Student Text 6 20 should be consulted before evaluating detector tube re sponse For example directions for many types of detector tubes offer a humidity correction chart used to modify the readings under different humidity conditions Other types of interference include sunlight and radio waves Though calibration checks verify that an instrument is responding appropriately to its check gas they may not reflect the action of some interferences It is up to you to determine if interfering compounds are present usually by comparing the response of one type of instrument to the response of another Because temperature and humidity can affect the operation of the instrument let the instrument equilibrate to outside temperature and humidity before using it In some cases taking the instrument from a climate controlled atmosphere to a warm humid atmosphere can cause the sensors to fog up Questions 1 What effect does the vapor density of a gas have on your sampling methods Why 2 In what situations might a
42. hylamine Ozone Phenol Propyl Mercaptan Putrescine Pyrdine Skatole Styrene Sulfur Dioxide Tert Butyl Mercaptan Thiocresol Thiophenol Toluene Triethylamine Vinyl Acetate Xylene Module 6 Detection Devices Detectable Odor Level About 1 ppm 0 004 ppm About 1 ppm About 100 ppm Much less that 1 ppm 0 00005 ppm 0 037 ppm 0 0003 ppm About 5 ppm 0 00019 ppm 9 9 Less than 1 ppm 0 01 ppm 0 00018 ppm 0 000029 ppm 0 016 ppm 0 0035 ppm 0 001 ppm 0 000048 ppm About 10 ppm 0 00019 ppm 0 83 ppm 0 0047 ppm 9 About 100 ppm About 100 ppm 0 001 ppm 0 021 ppm 0 001 ppm In ppb level 0 000075 ppm 9 0 0037 ppm 0 0012 ppm Less than 1 ppm 0 009 ppm 0 00008 ppm 0 001 ppm 0 000062 ppm About 1 ppm 0 08 ppm Less than 1 ppm Less than 1 ppm MW 44 5 74 15 17 03 104 22 124 21 73 14 102 18 70 91 128 55 90 19 129 25 101 19 45 08 186 28 62 1 45 08 34 1 17 15 48 1 31 05 48 76 16 88 15 79 1 131 2 64 07 90 19 124 21 110 18 101 19 6 135 IAFF Training for Hazardous Materials Technician Student Text 6 136 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Appendix D Slide Script for Instructors Module 6 Detection Devices 6 137 IAFF Training for Hazardous Materials Technician Student Text 6 138 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technicia
43. ially organic lead and silicon compounds These materials form fumes that coat the wire filaments Eventually the filaments will no longer reach the proper temperature or the catalyst will become completely covered Gases will no longer burn on the wire and the sensor will have to be replaced The instrument may appear to work properly even when the sensor is no longer functional Because of this vulnerabil ity it is extremely important to conduct a calibration check before and after each use Calibrating Typical CGI calibration gases include methane pentane and hexane Two meters from two different manufacturers may be calibrated to the same gas yet respond differently to other gases because they use different catalysts Re sponse curves or conversion factors should be used only with the make and model for which they are supplied Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Questions 1 What is the CGI calibration gas for your CGI 2 If two CGIs from different manufacturers are calibrated to the same gas yet respond differently to other gases what should you do 3 What can be done to simplify use of the meter with respect to response curves Interpreting Results Interpreting the readings from a CGI is easiest when the gas in the atmosphere being tested is the same as the gas to which the instrument was calibrated An example
44. ies Equipment Detection Range A detection device is manufactured to detect a hazard within a certain range of concentrations If the instrument is used to detect hazards outside that range the instrument will not provide valid or reliable results Meters can mea sure in gas LEL or ppm equivalents For example a gas combustible gas indicator measures in the percent range Other instruments such as flame or photoionization detectors are designed to detect gases and vapors in ppm equivalents Activities Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Detection Relative Response As discussed earlier instruments are calibrated to a specific vapor or gas Each instrument responds to any vapor or gas as if it is detecting its calibrant gas The reading an instrument displays may be higher or lower than the actual concentration when vapors or gases other than the calibration gas are present This is known as the instrument s relative response the instrument s response or reading relative to the calibration gas The response is therefore expressed as calibration gas equivalents If operating properly the instrument will respond consis tently higher or lower to a given vapor or gas relative to the calibration standard Conversion factors or relative re sponse curves can be used to convert the instrument reading to a true concentrati
45. ing a consistently high back ground reading The instrument fuel supply will last approximately six to eight hours of continuous use Because these instruments have a flame a combustible gas indicator must be used first to establish that the environ ment is not explosive Another important limitation is that oxygen must be present in order for a FID to burn the sample Insufficient oxygen will extinguish the flame Some FIDs operate in two different modes survey mode and gas chromatography mode Other FIDs offer only a survey mode which is the most commonly used Survey Mode When operating in the survey mode a FID continually draws air into the combustion chamber where it is burned The resulting signal is translated on the meter as the con centration of total organic vapors The meter display has a scale of O to 10 This scale can be set to read O to 10 O to 100 or 0 to 1 000 ppm or an even greater range by using the appropriate scale factor Gas Chromatography Mode To operate a FID qualitatively it must be equipped with the gas chromatograph GC features In the GC mode this instrument is able to separate a sample into its different components and detect each of them Depending on the instrument setup each component will have a characteristic response to the instrument Use of the instrument in this way requires extensive training and practice A FID in the GC mode works differently than in the survey mode In the GC m
46. ion Devices Student Text IAFF Training for Hazardous Materials Technician Appendix A Activities Module 6 Detection Devices 6 77 IAFF Training for Hazardous Materials Technician Student Text 6 78 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Instructor Notes Module 6 Detection Devices 6 79 IAFF Training for Hazardous Materials Technician Student Text 6 80 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Oregon Case Study Activity 1 An independent contractor arrives at a local sawmill to inspect a backflow valve on a city water line The contractor has performed the same annual inspection in the past without encountering problems and is licensed and certified by the state to perform such inspections The backflow valve is in an underground vault about 8 feet deep with about 14 inches of water on the bottom The contractor removes the manhole cover and enters the vault Half an hour later a truck driver notices the open manhole and sees a body floating face down in the water at the bottom of the vault He notifies the office at the sawmill which requests emer gency assistance Before help arrives the supervisor at the sawmill attempts a rescue A few seconds later a maintenance worker also enters the vault to help Neither is wearing respiratory protection Within two to three minutes both men are unconscious Shortly
47. itivity and selectivity of other instruments in your depart ment Explain that a properly set low level alarm for LEL on a CGI meter is 1096 of the LEL for the gas it is calibrated to Most CGIs are calibrated to hexane pentane methane or propane In many cases responders must use CGI meters to measure a gas other than the calibrant gas In these cases responders have two options 1 Calibrate the CGI meter to pentane hexane or toluene commonly available calibration gases and set the alarm level to 10 of the LEL The meter will respond conservatively for commonly encountered gases and vapors and will most likely indicate that 10 of the LEL is being observed when less than 10 actually exists This is a practical efficient simple method for use of CGI meters and minimizes or removes the need for calibration charts and calculations 2 If the gas being measured can positively be identified response factors or graphs supplied by the manufacturer of the meter may be used to determine the actual concentration being detected Using graphs response curves allow you to convert a meter reading in LEL to the actual LEL of the material involved Response factors are specific numbers by which the meter reading is multiplied in order to obtain the concentration of the actual gas involved Response curves and factors are specific to each CGI model and manufac turer and should not be interchanged Demonstrate how your CGI meter has the alarm set a
48. l protective equipment Safe areas and evacuation zones Control tactics Despite what some marketing information leads you to believe there is no readily available cost effective instru ment that will identify unknowns and tell you exactly how much is present Monitoring can be done to determine the level of a known hazard For example if a tank truck containing carbon disulfide is involved in an incident and begins leaking responders must establish a safe area for the warm zone Because the hazard is known team members can use a detection device specific to carbon disulfide to rapidly and easily monitor the surrounding air In other situations monitoring may be performed to iden tify an unknown hazard to decide if a hazard is present or to determine when it is no longer necessary to use personal protective equipment Monitoring also provides informa tion for assessing potential safety and health effects and for documenting exposure for post incident medical surveil lance In an emergency situation specific information about the type and level of the hazard must be readily obtainable Most detection tools provide readout information in real time that is a readout at the time the monitoring is being performed These are also known as direct read out instruments The information provided here about selected pieces of equipment is generic Specific information should be obtained from equipment manufacturers It is i
49. lled the ionization potential IP of that atom or molecule The IP is a unique value for a specific compound Ionization potentials are expressed in electron volts eV Ultraviolet radiation as found in the lamp of a PID is capable of causing this ionization There are several UV lamps available with varying levels of ionization potentials When a chemical compound with an IP less than the eV capacity of the PID s ultraviolet lamp is bombarded with UV light it loses electrons These negatively charged electrons are attracted to a metal grid within the ionization chamber The grid conducts a small amount of current and the electrons attracted to the grid produce a change in current The change is amplified and displayed as a ppm equivalent So the meter reading is proportional to the current charge which in turn is dependent on the number of electrons attracted to the grid upon ionization Anything that interferes with the light transmission can affect instrument readings Water vapor humidity in the ionization chamber acts like fog on a dark night scattering and reflecting light back toward the source Gases that cannot be ionized because of their high ionization potential will affect the instrument in the same way Meter responses can be decreased dramatically when high humidity or non ionizing gases are present It is important to note that not all chemicals with ionization potentials below the strength of a PID UV lamp will be d
50. locations based on environmental conditions and information you know about the hazard For example in an incident involving a leaking cylinder of chlorine gas reference materials can be used to determine that the vapor density of chlorine gas is 2 4 This means the material will hug low lying areas and pool in areas where Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials there are barriers blocking further dispersion If the leak is outside determine wind direction and speed so you can intelligently select sampling locations Documentation of monitoring locations is essential De scribe locations so other individuals can locate the same spot Include information such as distance direction and elevation from the source This allows the data to be more accurately evaluated Also take subsequent instrument readings at the same location so you can compare informa tion as conditions change Interferences Some hazardous vapors and gases interfere with proper operation of monitoring instruments Such interferences can result in decreased instrument sensitivity or false readings For example the silicone sprays used on electri cal contacts can damage CGI sensors over time Water vapor and relatively low concentrations of methane can interfere with the readings of a photoionization detector High levels of CO will over a period of time de
51. luded General considerations and precautions in hazardous materials monitoring Basic sampling techniques Evaluating meter readings The function and operation of the following instruments Combustible Gas Indicators Oxygen Meters Carbon Monoxide and Hydrogen Sulfide Meters Colorimetric Detector Tubes Radiation Survey Meters Photoionization Detectors Flame Ionization Detectors Organic Vapor Analyzers A review of other methods of detecting hazardous materials Basic guidelines for using detection devices at hazardous materials incidents Knowing how you respond to emergencies in your first due areas would you change your actions or habits based on the information covered in this module Listed below are some suggested actions Some you may already do and others may not fit your work environment If there are actions you have not done in the past do you think you will begin doing them as a result of this training As a result of this training I will Practice using the detection devices available in my department Practice better sampling techniques Compare measurements among detection devices and with other resources at an incident scene prior to taking action Take more care in selecting the right instrument for the right chemical and the right situation Create my own action statement Module 6 Detection Devices 6 75 IAFF Training for Hazardous Materials Student Text 6 76 Module 6 Detect
52. mosphere a photoionizer measures 500 ppm Assuming this value is accurate what is the percent volume of benzene in air Does this concentration indicate an immediate flammability hazard 6 126 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Comparing Instrument Responses Activity 15 At an isopropyl alcohol spill you obtain a reading of 10 LEL using your CGI 1 What is the actual LEL present 2 Some of the spilled material may have entered the sanitary sewer by way of an illegal sump pump connection Your meter gives a reading of 1096 LEL when the sample line is lowered into the sewer What does this suggest 3 A nursing home is situated 200 yards slightly downhill from the spill area Hazardous materials team members use a CGI and get readings between 0 and 1 LEL in the first floor social room Readings in residents rooms on the second floor give 0 LEL What does this indicate 4 How can you confirm the CGI readings 6 Team members also have a PID with a 10 2 eV UV lamp available Can this instrument be used to measure low ppm concentrations of isoproyl alcohol The ioniza tion potential of isopropyl alcohol is 10 1 Module 6 Detection Devices 6 127 IAFF Training for Hazardous Materials Technician Student Text 6 128 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials TechnicianO Appendix B Manufacturers and Suppliers of Detection
53. mportant to become thoroughly familiar with each unit prior to use in the field Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Detection Devices Limitations In addition to knowing how to use monitoring equipment it is important to keep in mind that this equipment cannot make decisions Like all equipment detection and moni toring devices perform specific functions and provide only limited information Further if the equipment is not prop erly maintained and operated the information obtained may be incorrect If you use detection equipment you must be well trained and ensure that the equipment is used within its limits Choose the right meter for the right chemical in the right situation There is no one monitoring device for every incident For an accurate picture of the atmosphere at an emergency you must use a combination of instruments at a minimum a combustible gas indicator and an oxygen meter Finally detection and monitoring equipment and the information generated by these devices must be used within an Incident Command System It is most effective when one person the Incident Commander can integrate various pieces of information into a whole picture and direct subsequent activities based on this information Team members using detection and monitoring equipment should however continually question the information generated
54. n Module 6 Detection Devices 6 139 IAFF Training for Hazardous Materials Technician Student Text 6 140 Module 6 Detection Devices
55. n incident involving radioactive materials a radiation survey meter is used to determine the type of radiation present alpha beta gamma and its level Use meter readings and radiation safety guidelines to delineate safe and restricted zones In addition to radiation survey meters personal dosimeters can be used to estimate an individual s dose of radiation these direct read out instruments are often the shape and size of a penlight Consulting with a health professional trained in radiation will help determine the devices that are appropriate for a specific hazardous materials team Instrument Operation One radiation detection device is the Geiger Mueller tube also known as a Geiger Counter or GM Counter In recent years they have been replaced by newer more accurate technology A radiation survey instrument commonly found in fire departments today is the Ludlam Meter named after the manufacturer The Ludlum Survey Meter is a portable survey instrument with four linear ranges used in combination with dose rate or cpm meter dials Four linear range multiples of x0 1 x1 x10 and x100 are used in combination with the 0 2mR hr meter dial 0 200 mR hr can be read with a range multiplier Most radiation survey instruments work on the principle that radiation causes ionization in the detecting media The ions produced are counted and reflect the relationship between the number of ionizations and the quantity of radiation present
56. n the actual concentration is less than 7096 LEL Xylene burns cooler so the meter reads less than 50 LEL when a 10096 LEL condition exists Methane Pentane Meter Reading 50 LEL 25 50 75 Actual Concentration LEL RELATIVE RESPONSE MSA MODEL 260 Relative Response A properly set low level alarm on a CGI meter is 10 of the LEL for the calibration gas The reason this percentage is fairly low is that it serves as a safety factor to account for differences in the instrument s relative response Module 6 Detection Devices 6 27 IAFF Training for Hazardous Materials Student Text 6 28 Questions 1 Based on the previous example for unknown spill situations which would you rather have your meter calibrated to methane or pentane 2 If you select methane what would the approximate actual concentration of pentane being monitored at a spill be when the meter reads 1096 of the LEL 3 Isthis good Oxygen is required for proper functioning of any CGI since oxygen is necessary for the combustion of the gas or vapor Manufacturers instructions should indicate the minimum concentration of oxygen required Most instruments will not give an accurate reading at less than 10 oxygen Oxygen enriched atmospheres will enhance the catalytic combustion process and will result in false high readings The catalytic filament is vulnerable to contaminants such as sulfur compounds heavy metals espec
57. ncentration of a chemical present Photoionization Detector 6 47 IAFF Training for Hazardous Materials Student Text Instrument Operation Components The basic components of one commonly used field photo ionization unit include a battery meter readout analog display or digital and an ultraviolet UV lamp detector meter lamp power readout supply Ion Chamber battery Bias Readout Unit Ion Chamber Portable Photoionization Detector The HNu photoionizer can be equipped with a chart re corder for documenting instrument readings but this negates the intrinsic safety warranty and makes it impos sible to use it as a portable survey instrument In addition to a real time display some PIDs have built in data loggers that can store hundreds of data points Data can be retrieved by direct printout or by downloading to a personal computer 6 48 Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials lonization Potentials of Chemicals In order to understand how a photoionizer works it is important to understand the process of ionization Elec trons which are negatively charged particles are held in orbit around the nucleus of an atom or molecule The nucleus carries a positive charge keeping the electrons in their orbits The energy required to remove the outermost electron from the atom or molecule is ca
58. nitial color of the indicating layer and what color change indicates the presence of the gas detected by the CGI 5 Can it be used to confirm the presence of 100 LEL concentrations 6 There is no color change when the indicator tube is placed backward in the pump that is with the arrow facing away from the pump during sampling Is this a valid result or should the test be repeated Module 6 Detection Devices 6 111 IAFF Training for Hazardous Materials Technician Student Text 6 112 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Detector Tube Activity 11B Instructor Notes Divide the class into groups of two or three to conduct the exercise Each participant must have the opportunity to use detector tubes You will need the following materials Detector tubes and pump piston assembly Contaminants for each detector tube alcohols acetone toluene Several one quart jars Detector Tube Worksheet or record used by your department Provide participants with detector tubes appropriate for the available contaminants For con taminants such as alcohol acetone or toluene add a few drops to an unmarked jar or place a cotton ball soaked with the material in the jar Use the contaminants sparingly By the end of the exercise it is likely that much of the liquid will evaporate making the classroom an uncom fortable environment in which to work In addition interferenc
59. non intrinsically safe moni toring device be used Environmental Conditions Environmental conditions may affect the operation of monitoring instruments as well as the dispersion of hazard ous materials Humidity temperature barometric pressure and direct sunlight are among the more common conditions known to affect instrument response Some instruments lose sensitivity at high humidity In particular very high humidity decreases the sensitivity of photoionizers by preventing the detection of some gases and vapors Some detector tubes also lose sensitivity because the humidity interferes with the chemical reaction that takes place in the tube High voltage power lines or hand held radios may influence analog display instruments causing the needle to fluctuate or drop below zero This effect can be countered by remov ing the instrument from the area of high voltage lines using Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials a sample line to bring the test atmosphere to the instrument or limiting the use of hand held radios in close proximity to meters Direct sunlight affects some digital readouts LCD readouts tend to black out when exposed to direct sunlight for a period of time It may take several minutes for the readout to return to normal Review the instrument operating manual for the effects of adverse environmental conditions on
60. nts provide measurements in real time B Measurements from direct read out instruments do not need to be converted C Measurements from direct read out instruments are displayed digitally D Direct read out instruments detect specific chemicals Module 6 Detection Devices 6 7 IAFF Training for Hazardous Materials Student Text 10 Which of the following instruments should you use in a flammable atmosphere Instruments marked UL Instruments marked FM Instruments marked intrinsically safe Instruments marked non incendive Hon gt Which of the following is the best definition of relative response as it applies to detection devices A The instrument s reading compared to the calibration gas B The instrument s reading over the period of the response time The instrument s reading in response to a specific class of chemicals D The instrument s reading in response to measurements from other devices If you are monitoring a gas with an LEL of 296 and your combustible gas indicator reads 5096 LEL what is the actual percentage of gas in the atmosphere A 196 B 2 C 25 D 50 An atmosphere is assumed to be oxygen enriched if concentrations of oxygen are greater than A 19 5 20 9 C 23 5 D 25 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Introduction Questions For each of the following scenari
61. ode the sample to be separated is 6 55 IAFF Training for Hazardous Materials Student Text 6 56 injected into a column packed with an inert solid a carrier gas hydrogen flows through the column As the carrier gas forces the sample through a column the separate components of the sample are retained on the column for different periods of time The amount of time a substance remains on the column known as retention time is a function of its affinity for the column material column temperature and flow rate of the carrier gas Lighter molecules such as butane are drawn through the column more quickly than larger molecules such as polypropylene Gas in 0 00 sample injection G C Column Gas i in 0 45 large and and small LJ E are being separated inside column wit TT aa Gas in 5 1 30 the lighter and smaller molecules pass through before the heavier and larger molecules Retention Time The response of an organic vapor analyzer in the GC mode can be compared to a known standard for identification Also the user can determine the level of air contaminant downwind of a release by comparing it to readings from the source of the release To successfully use the organic vapor analyzer in the GC mode the operator must have a general idea of the vapors and gases that may be present in the sample Without that knowledge the instrument will be of minimal use Module 6 Detection
62. on of the known vapor or gas You should have this information before beginning monitoring The use of these conversion factors will be discussed separately under each applicable piece of equipment Activity Response Time When monitoring at a hazardous materials incident it is important to obtain information as early as possible Data generated by monitoring instruments is not instantaneous The time it takes the instrument to obtain the sample and produce a reading depends on the length of the sample hose the flow rate of the pump and the length of time the detector requires to generate a response For example a combustible gas indicator with a 6 foot hose will respond more quickly than one with a 25 foot hose In addition the presence of a contaminant or other interfer ence can slow response time No instrument is truly instantaneous some respond in 5 to 10 seconds others require 30 to 60 seconds Consult the instrument operation manual and allow appropriate time for 6 15 IAFF Training for Hazardous Materials Technician Student Text 6 16 the instrument to respond completely before recording the reading Continue sampling in the same location while waiting for the response Activity Inherent Safety Most monitoring instruments require electricity to operate Electrical or electronic circuitry can be a source of ignition in a flammable atmosphere If an instrument is going to be used in such an atmosphere it
63. or operation and they can be calibrated for a wide range of gases They are often used to detect leaks in industrial applications For example they are used in the semicon ductor industry to check for leaks of gases such as phos 6 37 IAFF Training for Hazardous Materials Student Text 6 38 phine arsine and silane Solid state sensors require fre quent calibration because of sensor drift associated with temperature effects or other factors Sensor life is also relatively short Activity Module 6 Detection Devices Student Text Cotton Plug Pre Filter Module 6 Detection Devices IAFF Training for Hazardous Materials Detector Tubes Detector tubes are very useful for measuring the concentra tion of known vapor or gas contaminants in air Detector tubes however only indicate if a chemical is present They should not be used as the sole basis for determining entry into a hazardous atmosphere Detector tubes respond to a specific chemical or group of chemicals The concentration of contaminant is determined by observing the color change in the tube Depending on the tube selected the scale may be read in ppm or percent Some tubes have a millimeter mm scale and the user must refer to a chart to determine the concentration Other tubes indicate only the presence of a contaminant without indicating the relative concentration Glass Vial Indicating Chemical
64. or three to conduct the exercise You will need the following materials Photoionization detector Flame ionization detector Check gas for instruments Samples of gases vapors similar to those used for the exercise To allow parison of performance of the instruments include ammonia wet cotton ball and methane Two of the samples should be known quantities to allow participants to check precision accuracy of the instruments Air Monitoring Record Instrument Checklist to be developed by Instructor Develop an Instrument Checklist to simplify procedures for turning on the machine checking calibration and taking measurements Observe participants checking the calibration of their instruments before and after monitoring Supervise participants in the use of the instruments on various samples Questions 1 Which instrument was most sensitive to each of the unknowns Why 2 Compare your results with the identities and concentrations of the unknowns given by your instructor Which instrument is more precise Why 3 How do you think the LEL CGI would measure each of the unknowns at these concen trations 4 A benzene detector tube indicates a concentration of 95 ppm An HNu photoionizer calibrated to benzene gives a reading of 215 ppm in the same atmosphere Why the difference Module 6 Detection Devices 6 125 IAFF Training for Hazardous Materials Technician Student Text 5 In a benzene at
65. os what would be your initial actions What type s of detection devices would you use 1 Your hazardous materials team responds to a leaking propane tank at 2 00 a m The one ton tank is on top of a small construction building It was being moved by a crane when it was accidentally smashed into a wall breaking off an outlet pipe You can hear propane leaking The construction company wants to restart the crane to move the propane tank down to ground level 2 Your hazardous materials team responds to a basement where unknown chemicals have leaked into the bottom of an elevator shaft 3 Your hazardous materials team responds to a natural gas leak inside a large warehouse 4 Your hazardous materials team responds to a leaking ammonia rail car outside on a warm day 5 Your hazardous materials team responds to a vehicle accident involving a medical courier carrying radioac tive isotopes for patient treatment 6 Your hazardous materials team responds to a shopping mall for an unknown odor 7 Your hazardous materials team responds to a green liquid spill in a drainage ditch Module 6 Detection Devices 6 9 IAFF Training for Hazardous Materials Student Text 6 10 When to Monitor Detection equipment provides additional information about a product so you can take the safest approach when you respond to a release Specifically monitoring equipment helps you determine Appropriate persona
66. ound radiation it is likely that the item is contaminated Measure source radiation at various distances next Radia tion activity decreases as distance from the source in creases Team members may encounter radiologic materials as a result of transportation incidents If radiological packaging is encountered under these circumstances it is important not to disturb the packaging The transport index should be noted in the white box on the lower half of the label on the container This is the maximum dose equivalent rate expressed in mrem per hour measured at one meter from Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials the external surface of the container Shipping papers can be consulted for information about the form of the radioac tive source Personal Dosimeters Personal dosimeters monitor the accumulated dose received by the dosimeter Results of exposure or non exposure can be documented so medical personnel can assist in evaluating radiation related ilInesses Dosimeters are available in several styles e g pencil badge ring Some types pencil can be read on the scene Most other types are typically sent to a lab for analysis with a report being generated Limitations The primary disadvantage of personal dosimeters is that they indicate the dose of radiation that has already been received Dosimeters also do not sh
67. ow how fast the dose is being delivered unlike survey meters Although personal dosimeters are fairly rugged some can be damaged by shock heat light and moisture Pocket Dosimeters 6 45 IAFF Training for Hazardous Materials Student Text Questions Briefly summarize the characteristics of radiation survey meters Type of hazard Method of detection Calibration standard Check standard Range of detection Response time Power source Operating temperatures Key limitations Activities 6 46 Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Photoionization Detectors Photoionization detectors PIDs are general survey instru ments designed to detect organic vapors and gases in the low ppm range They can also detect a small number of inorganic gases though many of these inorganics are halogens or halogenated compounds Since these com pounds are corrosive they can damage instruments that are not corrosion resistant Most PIDs are not corrosion resis tant Photoionizers are useful for general atmospheric monitor ing characterizing release plumes screening samples and evaluating relative differences in concentration from one location to another They cannot determine the identity of unknowns in the air they indicate only that there is a high or low co
68. own and a response curve or factor is available the action level is 5046 of the actual LEL Unknown materials have an action level of 25 LEL in the Hot Zone For many cool burning materials a 25 LEL meter response can correspond to actual concentra tions above 5096 LEL At only slightly higher meter readings the actual LEL can approach 75 to 100 LEL Other Action Levels Action levels have been defined by the Occupational Safety and Health Administration and the American Conference of Governmental Industrial Hygienists for workplace exposures to many commonly encountered chemicals The 8 hour maximum exposure levels can be used as action levels in emergency response Mea surements can establish the appropriate size of the Hot Zone and safe areas for unprotected personnel When the contaminant is unknown responders must rely on the instruments on hand to provide a general indication of the relative health risks that may be present A CGI reading of 1 LEL should indicate an action level from a health standpoint The 146 reading suggests that there are at least 100 ppm and possibly much more of a combustible gas present Similarly a 0 1 decrease in oxygen concentration may represent a concentration of an unknown of 5 000 ppm When such readings are obtained the area should be considered hazardous requiring appropriate respiratory and skin protection for entry Protect Instruments From Contamination Instruments can often
69. ple if your instrument is equipped with a ten foot sampling line you may have to wait 20 seconds at a location to obtain a stable reading Mechani cal pumps usually sample more quickly and reliably than hand aspirated pumps 6 17 IAFF Training for Hazardous Materials Technician Student Text 6 18 Non Instrument Factors Likely to Influence Readout Data Any information you can gather about the material involved can assist you in choosing monitoring strategies The team member preparing to sample the environment should consider the following questions 5 the material organic or inorganic Which instrument is most appropriate to use for detection and monitoring What is the lower explosive limit lower flammable limit of the material Is there sufficient oxygen for the instrument to produce an accurate response What is the vapor pressure of the material Given the ambient temperature is it likely that the liquid will generate enough vapors to support combustion Will liquid present generate enough vapors to create a potential health hazard e What is the vapor density of the material is the mate rial lighter or heavier than air e What are the various exposure limits for the substance e How is the instrument likely to respond to the sub stance Location of Monitoring Monitoring must be carefully planned so that time and resources are not wasted in gathering information Choose monitoring
70. rates of the gamma sources Module 6 Detection Devices 6 117 Student Text IAFF Training for Hazardous Materials Technician Use the following grid to graph the relationship between the level of radiation and dis 4 tance from the source Take three to four readings doubling the distance from the source for each reading Distance Module 6 Detection Devices 6 118 Student Text IAFF Training for Hazardous Materials TechnicianO PID Activity 13A Instructor Notes Demonstrate how PIDs can be affected by humidity Explain that one component of a PID sensor is glass Use a piece of glass a watch glass or simply a window and breathe on the glass to fog it Explain to the students that in a PID meter this fogging from humidity can affect the instrument s operation If your instrument has a digital readout you can demonstrate the effect of sunlight by having the students observe the readout in direct sun Some meters are more prone than others to radio interference from units like hand held radios You can demonstrate this to the students by keying a microphone to your meters Observe which meters receive interfering signals and at what distance the interference occurs Module 6 Detection Devices 6 119 IAFF Training for Hazardous Materials Technician Student Text 6 120 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials PID Activity 13B A drum of parti
71. regulations state that atmospheres with 19 5 oxygen and above are safe for use with air purifying respirators While an atmo sphere of 19 596 oxygen may be acceptable in terms of oxygen concentration it can still be extremely hazardous due to the presence of other gases and vapors Approxi mately 5 of a displacing gas is needed to drop the oxygen concentration by 1 In many cases 5 of a gas or vapor is very hazardous It is important to emphasize that both an oxygen meter and a CGI are necessary for assessing an unknown environment because it is possible to detect a high LEL concentration without a significant change in oxy gen concentration An oxygen enriched atmosphere greater than 23 5 is particularly hazardous Although several instruments can measure oxygen enriched atmospheres no testing or other work should ever be performed under such conditions because a spark arc or flame could lead to fire or explo sion 6 35 IAFF Training for Hazardous Materials Student Text Oxygen Meter Summary Questions Briefly summarize the characteristics of oxygen meters Type of atmosphere Method of detection Calibration standard Check standard Range of detection Response time Power source Operating temperatures Key limitations Activity 6 36 Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous
72. result will be a false negative read ing 3 Remember absence of evidence is not evi dence of absence From The Cosmos Carl Sagan Simply because a device produces no reading does not mean that no contamination is present The device you are using may not be capable of detecting the type or concen tration of contaminant present For this reason use mul tiple types of air monitoring instruments to confirm the presence or absence of contamination 6 61 IAFF Training for Hazardous Materials Student Text 6 62 Questions Using the scenario of gasoline in the sewer suppose that there is a sufficient concentration of oxygen in the sewer to use a CGI 1 Does a reading of 0 LEL prove that no gasoline is present 2 Does a CGI reading of 15 LEL mean that gasoline is present in the sewer 3 If your answer to the previous question is no how would you identify the chemical producing the 1596 LEL response can be used with filters to determine the presence of specific chemicals For example in the sewer scenario described above you could attach an activated charcoal filter to the CGI to remove gasoline vapors from the sample before they reach the sensor Light hydrocarbon gases such as methane pass through the filter and there will be no decrease in LEL detected if methane gas is responsible for the meter readout 4 Never assume only one hazard is present Team members may fo
73. s IAFF Training for Hazardous Materials Student Text 6 6 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Module 6 Prerequisite Quiz 1 Which of the following is the best definition of response time as it applies to detection devices A The period between beginning measurement and the initial reading B The period between beginning measurement and obtaining a reading C The length of time required to obtain a sample D The length of time it takes a device to adjust for the calibration standard 2 Detector tubes are used to A Measure the concentration of known gases vapors and unknown hydrocarbons B Identify specific gases in an atmosphere Distinguish between specific gases within a hazard class D Detect flammable atmospheres 3 Alpha and beta radiation survey meters usually display readings in A Millroentgens per hour B Millirems per hour Counts per minute D Percentages of LEL 4 On a combustible gas indicator with a reading in LEL the reading indicates 0 100 of A The explosive gas in the atmosphere B The non explosive gas in the atmosphere C The lower explosive limit D The flammable range 3 The most common calibration gases for combustible gas indicators are A Methane pentane B Pentane oxygen C Methane xylene D Oxygen methane 6 Which of the following is true of direct read out instruments A Direct read out instrume
74. s Soak cotton balls with butane alcohols etc and place them in jars with tight fitting lids Air Monitoring Instrument Record Supervise participants as they use the instruments to determine oxygen concentrations and LEL UEL of the various samples Participants need only record the measurements of known samples those in the beach balls but should note the reaction of the instruments to the other available samples Make sure that participants do a field check of their CGI prior to and on completion of monitoring Questions 1 What does each reading indicate What course of action would you take based on the readings 2 What are the advantages and limitations of each instrument 3 Two different CGI models have Class I Division 1 Groups A B C and D approvals One is approved as Intrinsically Safe and the other as Explosion Proof Can both instruments be used under the same conditions 4 A subsurface gasoline leak is being monitored with a combustible gas indicator Initial readings are greater than 5096 of the LEL but as the survey continues concentrations decline and are finally undetectable by the CGI Can you account for this 5 A tank car is leaking carbon dioxide in an area of uneven terrain What instruments are required for site entry 6 What is indicated by an 1196 oxygen level in a confined space Module 6 Detection Devices 6 107 IAFF Training for Hazardous Materials Technician Student Text 6 10
75. st paper for determining the pres ence of a specific hazard or a hazardous characteristic There are test papers for acids and bases pH paper oxi dizers and peroxides and sulfides Test paper is useful for liquid releases such as acids and bases oxidizers and peroxides and sulfides When the identity of a spilled material is unknown one of several kits can be used to determine the contents Test strips with colorimetric tests for a variety of hazard charac teristics and chemicals are available from other manufactur ers Using these strips you can test for oxidizers fluorides petroleum products halogens and pH HazCat is a field characterization kit that allows you to evaluate the characteristics of an unknown chemical These kits help determine the class and in certain cases the specific chemical One disadvantage of a HazCat kit is that it requires handling and measuring test chemicals Personnel using this kit must be well trained Kits such as HazCat come complete with an extensive user s manual and guidance charts on how to conduct individual tests and evaluate results The test kits described above may require a few minutes to several hours to characterize the hazard Some kits incor porate hazardous chemicals into the test materials You must be completely familiar with the tests and test materials before using such kits to avoid inaccuracies and injuries 6 59 IAFF Training for Hazardous Materials
76. t 1096 of the LEL Use a variety of samples such as gasoline or acetone and show how the alarm will sound when the reading indicates 1096 of the LEL regardless of which material is being sampled Module 6 Detection Devices 6 95 IAFF Training for Hazardous Materials Technician Student Text 6 96 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Relative Response Activity 6 Instructor Notes Demonstrate how the manufacturer of your CGI recommends application of their response factors response graphs or response charts For example if your meter is calibrated to pentane the manufacturer may recommend you apply a response factor of 1 4 when monitoring natural gas That response factor must be applied as 10 LEL observed on meter x 1 4 14 LEL Response factors vary depending upon the manufacturer and the model of instrument Module 6 Detection Devices 6 97 IAFF Training for Hazardous Materials Technician Student Text 6 98 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician Instrument Response Activity 7 Instructor Notes Using one of your detection devices time the response of the instrument with and without a sample hose connected A general rule of thumb is to allow one second for every foot of sample hose Demonstrate how response time is affected by adding sample hoses of varying lengths Evaluate the fastest and slowest instr
77. t are manually checked can be adjusted to compensate for dirty lamps or grids decreased lamp output or other instrument factors that may affect readings The adjustment knob is often called a span potentiometer The span control adjusts the amplification of the current change similar to the volume control on a radio The span setting should be adjusted during the calibration check procedures according to the manufacturers instruc tions This setting must be locked into place and remain unchanged during use The setting must be documented Interpreting Results When the PID responds to the calibration gas the reading is equivalent to the actual ppm concentration present up to around 400 to 500 ppm Higher concentrations of the calibration gas are not measured accurately by the PID AII responses of the PID are relative to its response to the calibration gas Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials When another gas or vapor is present or when there is a mixture of gases the meter reading does not reflect the actual concentration present Rather it represents a change in the current across the grid as the materials in the air are ionized A meter response of 22 units represents a current change equivalent to that produced by 22 ppm of the factory calibration gas For this reason the readings are often called ppm calibration gas equival
78. te warm up time meter zeroing cleaning and decontamination and maintenance procedures Use only the attachments furnished with the instrument Other attachments may give off or absorb contaminants that will affect the instrument reading Activity 6 13 IAFF Training for Hazardous Materials Student Text 6 14 Instrument Calibration and Calibration Checks Monitoring instruments are calibrated at the factory to respond accurately to a particular vapor or gas within a specific concentration range Instrument response should be checked before and after each use against the calibration gas standard or a check gas if the calibration standard is not available or is danger ous to use This check verifies that the instrument is responding accurately to its calibration standard If the instrument responds the same each time it is likely that the instrument is and has been operating properly If the instrument calibration check is outside an acceptable response range as given by the manufacturer the informa tion you obtain during use may not be valid for evaluating the situation Send the instrument to a factory or an ap proved service center to be recalibrated The operating manual for the monitoring instrument should provide instructions for performing calibration checks The appropriate check standards and regulators must be avail able in the field All calibration checks must be docu mented Activit
79. terials that are similar in structure and reactivity Some manufacturers also produce tubes for groups of gases for example aro matic hydrocarbons Instructions should also list potential interferences that can cause inaccurate tube readings The chemical in the tube can react with air contaminants in addition to the gas or vapor to which it is calibrated A color change in the tube that is different from that expected may indicate that some other vapor or gas is present Also interfering gases or vapors may increase or decrease tube response Finally environmental conditions such as barometric pressure humidity and temperature can have a direct effect on the chemical reaction in the tube by increasing or de creasing tube response Manufacturers instructions may include temperature and humidity conversion factors Calibrating Detector tubes are calibrated to a specific vapor or gas It is not necessary to do a calibration check however it is important to check the expiration date of each box of detector tubes Also in order to improve performance and extend the shelf life of tubes they should be stored at temperatures recommended by the manufacturer Other Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials wise the tubes may not be good even if they are used prior to the expiration date Anything that affects a chemical reaction will a
80. time Power source Operating temperatures Key limitations Activities 6 31 IAFF Training for Hazardous Materials Student Text 6 32 Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Oxygen Meters Oxygen meters are used to detect the percentage of oxygen in atmosphere Most oxygen sensing devices used by fire departments are calibrated to indicate concentrations between 0 and 25 Oxygen meters are most useful when used in conjunction with a combustible gas indicator As discussed in the section on CGIs it is important to verify that there is sufficient oxygen for proper operation of the CGI Remember inadequate oxygen less than 10 will result in an inaccurate reading as will oxygen enriched atmospheres Instrument Operation An oxygen meter has two principal components an oxy gen sensing device and a meter readout In some units air is drawn to the oxygen detector with an aspirator bulb or pump in other units ambient air is allowed to diffuse into the sensor The detection of oxygen concentration is based on a chemi cal reaction in a detector cell Oxygen molecules diffuse through a semipermeable membrane in the oxygen detec tion cell Reactions between the oxygen and electrodes produce a very small electric current that is proportional to the sensor s oxygen content The current passes
81. ual concentration you are measuring 3 Is your CGI meter useful in detecting hydrocarbons in the 0 5 ppm range 4 Will a combustible gas meter detect a radioactive isotope Additional Instructions Your combustible gas meter may have sensors in addition to the CGI sensor Sensors for oxy gen hydrogen sulfide carbon monoxide cyanide and other chemicals are available Demon strate the detection range of each of those sensors Oxygen sensors typically detect oxygen levels in the in air range and alarm at both 19 5 low alarm and around 23 high alarm You can use the air present in the room as a calibra tion check for 20 8 O and your exhaled breath to obtain low O readings Use a medical O bottle to supply for increased levels of Module 6 Detection Devices 6 89 IAFF Training for Hazardous Materials Technician Student Text 6 90 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials TechnicianO Detection Activity 5B Instructor Notes Detector tubes typically measure results in parts per million ppm Demonstrate to the students how the detection range on a sample detector tube is determined Distribute unused detector tubes to the students along with the directions for those tubes Dis cuss how the detection range for different tubes varies depending on the number of pump strokes and the version of tube you have selected For example one pump stroke may have a range of 50 700 ppm
82. ument can be used for general surveys or as a qualitative instrument that can help you identify a chemical Use of a FID asa qualitative instrument requires additional training skill and knowledge Major FID components include a battery a combustion chamber where the sample is burned a detector a meter readout analog or digital and a supply of fuel usually a cylinder of hydrogen gas or a mixture of hydrogen and nitrogen gases Some organic vapor analyzers are also equipped with a gas chromatographic option and a chart recorder An advantage of FIDs over photoionization detectors is that they are not restricted by the ionization potential of the chemical contaminant because they have very high ioniza tion energy FIDs detect with varying sensitivity any material that can be burned that is anything that contains carbon This includes light hydrocarbon gases such as methane which has a very high ionization potential In addition humidity does not limit their use FIDs are generally very sensitive and can read into low ppm ranges particularly for low weight organic molecules like methane These instruments are common in the petro leum industry as leak detectors and gas detectors for very low levels of methane ethane propane and butane 6 53 IAFF Training for Hazardous Materials Student Text pressure supply pressure supply regulators indicator low capillary restrictor
83. uments you have available for the class and demonstrate to the students their differences in response times Ask for a volunteer to monitor the time Again you can use the samples such as acetone to obtain a reading Module 6 Detection Devices 6 99 IAFF Training for Hazardous Materials Technician Student Text 6 100 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Technician CGI Activity 8A You respond to a reported hexane spill Using your CGI with a LEL readout you obtain a measurement of 20 Questions 1 What is the meter response conversion factor for hexane for your instrument 2 What is the LEL of hexane 3 What is the actual concentration of hexane in terms of LEL and ppm hint 1 in air is 10 000 ppm Module 6 Detection Devices 6 101 IAFF Training for Hazardous Materials Technician Student Text 6 102 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials TechnicianO CGI Activity 8B A facility handling ethylene oxide has a fixed sensor alarm that sounds when high concentrations of the gas are detected The sensor indicates that there is a concentration of 4 500 ppm of ethyl ene oxide in the area but this should be confirmed with another instrument Questions 1 The LEL of ethylene oxide is 3 What reading should be expected a LEL CGI assuming the instrument is calibrated to a gas other than ethylene oxide 23 What is the corr
84. ur instructor has set up answer the questions below for each station Work Station 1 What is the name of this device 2 What is the primary purpose of this device 3 Does this device carry any approval markings that allow it to be used in potentially combus tible atmospheres If so what are they 4 List the items you should inspect when doing a field check on this instrument 5 What type of material does the manufacturer recommend you use to conduct a calibration check on this instrument 6 Use the device to sample the substances your instructor has provided and note your findings below Sample 1 Sample 2 Sample 3 Sample 4 7 Use the device to sample something outside the classroom or the building Record the item you sampled and the results 8 What questions do you have about this instrument Module 6 Detection Devices 6 71 IAFF Training for Hazardous Materials Student Text 6 72 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Action Statement Module 6 Detection Devices 6 73 IAFF Training for Hazardous Materials Student Text 6 74 Module 6 Detection Devices Student Text IAFF Training for Hazardous Materials Action Statement You have just completed the sixth module of the Hazardous Materials Technician course The topics inc
85. ut will show a 1 0 100 level or greater This indicates that the ambient atmosphere is readily combustible When the atmosphere has a concentration of gas above the UEL the instrument may react in one of several different ways If it is an analog meter the meter needle may rise above the 1 0 10096 mark and then return to zero A digital readout may freeze at this level NO METHANE BELOW LEL IN EXPLOSIVE 0 0 5 3 RANGE 5 3 14 OVER 14 CGI Response to Methane LEL 5 3 UEL 14 The illustration above shows an example of an analog CGI response in various environments Digital instruments display different types of warnings when concentrations are above the LEL such as over high or LEL In interpreting results the user must consider that a level of a combustible gas or vapor may be well below the LEL while the atmosphere may still be hazardous Concentra tions high enough to result in CGI readings of 10 to 25 of the LEL are likely to be toxic or immediately dangerous to life or health If toxicity is a concern a CGI with a ppm scale or another more sensitive instrument must be used 6 30 Module 6 Detection Devices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Questions Briefly summarize the characteristics of a CGI Type of atmosphere Method of detection Calibration standard Check standard Range of detection Response
86. vices Student Text Module 6 Detection Devices IAFF Training for Hazardous Materials Anyone responsible for evaluating information generated by monitoring equipment must have additional supporting data to justify subsequent actions Supporting information must include each of the points listed above These points particularly those relating to non instrument factors should be documented along with the equipment readouts A more detailed discussion of each of these factors illus trates their influence on the data generated by the instru ments Proper Equipment Operation Most portable monitoring instruments are easy to operate however all require thorough knowledge of operating principles and procedures to ensure proper functioning Never adjust settings on instruments without regard for the effect The most important initial check performed on an instru ment is the battery check Most analog display instruments have a battery check setting and the needle should show adequate power available Digital readout instruments often do not have a battery check option These instru ments display a low battery message when there is insuffi cient charge for instrument function If there is inadequate battery power turn off and recharge the instrument before you use it To operate properly an instrument must have sufficient battery power Other considerations regarding instrument operation in clude adequa

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