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Users Guide

1. 4 4 5 1 Tipping Prevention Bracket Installation 5 4 7 1 Front Control Panel 7 3 8 1 Chart of Various Bath Fluids and Their Properties 8 9 9 1 Controller Operation Flowchart 9 4 9 2 Bath Temperature Fluctuation At Various Proportional Band Settings 9 10 10 1 Serial Communications Cable Wiring 10 3 11 1 Calibration Example 11 4 7341 Users Guide viii 1 1 Chapter 1 Before You Start Title Page Symbols Used 1 3 Safety Information 1 4 Authorized Service Centers 1 7 7341 Users Guide 1 2 Before You Start Symbols Used 1 1 3 Symbols Used Table 1 lists the International Electrical Symbols Some or all of th
2. 9 3 Reset Cutout 9 3 Temperature Set point 9 5 Programmable Set points 9 5 Set point Value 9 5 Set point Vernier 9 6 Scan 9 6 Scan Control 9 6 lScan Rate 9 6 Temperature Scale Units 9 7 Ramp and Soak Program 9 7 Number of Program Set points 9 7 Set points 9 8 Program Soak Time
3. 9 8 Program Function Mode 9 8 Program Control 9 9 Secondary Menu 9 9 Heater Power 9 9 Proportional Band 9 10 Cutout 9 12 Controller Configuration 9 13 Probe Parameters 9 13 R0 9 13 Contents continued iii ALPHA 9 13 Operating Parameters 9 13 Cutout Reset Mode
4. 9 17 Calibration Parameters 9 17 7341 Users Guide 9 2 CTO 9 17 CO and CG 9 17 H and L 9 17 HGbt 9 17 Controller Operation Bath Temperature 9 9 3 This chapter discusses in detail how to operate the bath temperature controller using the front control panel Using the front panel key switches and LED display the user may monitor the bath temperature set the temperature set point in degrees C or F monitor the heater output power adjust the controller proportional band set the cutout set point and program the probe calibration parameters operating parameters serial and IEEE 488 interface configuration and controller calibration parameters Operation is summarized in Figure 9 1 Bath Temperature The digital LED display on the front panel allows direct viewing of the actual bath temperature This temperature value is what is normally shown on the di
5. 8 5 Ethylene Glycol 8 5 Mineral Oil 8 5 Silicone Oil 8 6 Fluid Characteristics Charts 8 6 Limitations and Disclaimer 8 6 About the Chart 8 8 Stirring 8 10 Power 8 10 Heater 8 10 Temperature Controller 8 10 Refrigeration 8 11 9 Controller Operation 9 1 Bath Temperature
6. 7 3 8 General Operation 8 1 Heat Transfer Fluid 8 3 Temperature Range 8 3 Viscosity 8 3 Specific Heat 8 3 Thermal Conductivity 8 3 Thermal Expansion 8 3 Electrical Resistivity 8 4 Fluid Lifetime 8 4 Safety 8 4 Cost 8 5 Commonly Used Fluids 8 5 Water
7. 2 1 3 Specifications and Environmental Conditions 3 1 Specifications 3 3 Environmental Conditions 3 4 4 Quick Start 4 1 Unpacking 4 3 Set Up 4 3 Power 4 5 Setting the Temperature 4 5 5 Installation 5 1 Moving or Uncrating the Bath 5 3 Bath Environment 5 3 Tipping Prevention Bracket Installation 5 3 Installation On A Wood Floor
8. 9 13 ALPHA 9 13 Operating Parameters 9 13 Cutout Reset Mode 9 13 Cooling Mode 9 14 Hot Gas Bypass Mode 9 14 Serial Interface Parameters 9 15 Baud Rate 9 15 Sample Period 9 15 Duplex Mode 9 16 Linefeed 9 16 IEEE 488 Parameters 9 16 IEEE 488 Address 9 16 Transmission Termination
9. 10 5 IEEE 488 Address 10 5 Transmission Termination 10 5 IEEE 488 Operation 10 5 Interface Commands 10 5 Cooling Control 10 5 11 Calibration Procedure 11 1 Calibration Points 11 3 Measuring the Set point Error 11 3 Computing R0 and ALPHA 11 3 Calibration Example 11 4 12 Maintenance 12 1 13 Troubleshooting 13 1 Troubleshooting
10. 10 5 Interface Commands 10 5 Cooling Control 10 5 7341 Users Guide 10 2 Digital Communication Interface Serial Communications10 10 3 The 7341 bath is capable of communicating with and being controlled by other equipment through the digital interface Two types of digital interface are available the RS 232 serial interface which is standard and the IEEE 488 GPIB interface which is optional With a digital interface the bath may be connected to a computer or other equipment This allows the user to set the bath temperature monitor the temperature and access any of the other controller functions all using remote communications equipment In addition the cooling may be controlled using the interface To control the cooling with the interface the cooling power switch must be ON Serial Communications The RS 232 serial interface allows serial digital communications over fairly long distances 15 24 meters With the serial interface the user may access any of the functions parameters and settings discussed in Chapter 9 Controller Operation with the exception of the baud rate setting The serial interface operates with eight data bits one stop bit and no parity Wiring The serial communications cable attach
11. 5 3 Installation On a Concrete Floor 5 4 Installation Of The Bath 5 4 Dry out Period 5 4 Bath Preparation and Filling 5 5 Power 5 5 6 Bath Use 6 1 General 6 3 Comparison Calibration 6 3 Calibration of Multiple Probes 6 4 7341 Users Guide ii 7 Parts and Controls 7 1 Front Control Panel 7 3 Back Panel 7 3 Fluid Expansion Reservoir
12. 9 17 H and L 9 17 HGbt 9 17 10 Digital Communication Interface 10 1 Serial Communications 10 3 Wiring 10 3 Setup 10 3 Baud Rate 10 4 Sample Period 10 4 Duplex Mode 10 4 Linefeed 10 4 Serial Operation 10 4 IEEE 488 Communication optional 10 4 Setup
13. 13 3 Comments 13 6 EMC Directive 13 6 Immunity Testing 13 6 Emission Testing 13 6 Low Voltage Directive Safety 13 6 7341 Users Guide 13 2 Troubleshooting Troubleshooting13 13 3 This section contains information on troubleshooting CE Comments and a wiring diagram This information pertains to a number of bath models and certain specifics may not pertain to your model Troubleshooting In the event that the instrument appears to function abnormally this section may help to find and solve the problem Several possible problem conditions are described along with likely causes and solutions If a problem arises please read this section carefully and attempt to understand and solve the problem If the probe seems faulty or the problem cannot otherwise be solved contact an Authorized Service Center see Authorized Service Centers in Chapter 1 for assistance Be sure to have the instrument model number serial number voltage and problem description available
14. 8 6 Limitations and Disclaimer 8 6 About the Chart 8 8 Stirring 8 10 Power 8 10 Heater 8 10 Temperature Controller 8 10 Refrigeration 8 11 7341 Users Guide 8 2 General Operation Heat Transfer Fluid 8 8 3 Heat Transfer Fluid Many fluids will work with 7341 bath Choosing a fluid requires consideration of many important characteristics of the fluid Among these are temperature range viscosity specific heat thermal conductivity thermal expansion electrical resistivity fluid lifetime safety and cost Use the fluid chart in the manual to choose the type of fluid that is best suited for you intended purpose Temperature Range One of the most important characteristics to consider is the temperature range of the flui
15. 9 13 Cooling Mode 9 14 Hot Gas Bypass Mode 9 14 Serial Interface Parameters 9 15 Baud Rate 9 15 Sample Period 9 15 Duplex Mode 9 15 Linefeed 9 16 IEEE 488 Parameters 9 16 IEEE 488 Address 9 16 Transmission Termination 9 17 Calibration Parameters 9 17 CTO 9 17 CO and CG
16. 13 3 Comments 13 6 EMC Directive 13 6 Immunity Testing 13 6 Emission Testing 13 6 Low Voltage Directive Safety 13 6 7341 Users Guide iv v List of Tables Table Title Page 1 1 International Electrical Symbols 1 3 3 1 Specifications 3 3 8 1 Various Bath Fluids and Their Properties 8 7 9 1 Program Mode Setting Actions 9 9 9 2 Typical Proportional Band Settings for Various Fluids 9 11 10 1 Interface Command Summary 10 6 7341 Users Guide vi vii List of Figures Figure Title Page 4 1 Stir Baffle Fill Levels
17. 8 3 Specific Heat 8 3 Thermal Conductivity 8 3 Thermal Expansion 8 3 Electrical Resistivity 8 4 Fluid Lifetime 8 4 Safety 8 4 Cost 8 5 Commonly Used Fluids 8 5 Water 8 5 Ethylene Glycol 8 5 Mineral Oil 8 5 Silicone Oil 8 6 Fluid Characteristics Charts
18. 9 7 Ramp and Soak Program 9 7 Number of Program Set points 9 7 Set points 9 8 Program Soak Time 9 8 Program Function Mode 9 8 Program Control 9 9 Secondary Menu 9 9 Heater Power 9 9 Proportional Band 9 10 Cutout 9 12 Controller Configuration 9 13 Probe Parameters 9 13 R0
19. 9 7 cooling The scan rate function appears in the main menu after the scan control function The scan rate units are in degrees per minute degrees C or F depending on the selected units Sr 0 010 Scan rate in C min Press UP or DOWN to change the scan rate Sr 2 0 New scan rate Press SET to accept the new scan rate and continue Temperature Scale Units The temperature scale units of the controller may be set by the user to degrees Celsius C or Fahrenheit F The units are used in displaying the bath temperature set point vernier proportional band and cutout set point The temperature scale units selection is accessed after the vernier adjustment function by pressing SET From the temperature display function access the units selection by pressing SET 4 times Un C Scale units currently selected Press UP or DOWN to change the units U Change units Un F New units selected Press SET to accept the new selection and resume displaying the bath temperature S Set the new units and resume temperature display Ramp and Soak Program The ramp and soak program feature allows the user to program a number of set points and have the instrument automatically cycle between the temperatures holding at each for a length of time The user can select one of four different cycle functions The program parameter menu is accessed by pressing SET and then UP 1 100 00
20. OFF transmission of a linefeed character LF ASCII 10 after transmission of any carriage return The default setting is with linefeed on The mode may be changed using UP or DOWN Press SET to set the sample period to the new value or EXIT to abort and skip to the next parameter Serial Operation Once the cable has been attached and the interface set up properly the controller will immediately begin transmitting temperature readings at the programmed rate The set point and other commands may be sent to the bath via the serial interface to set the bath and view or program the various parameters The interface commands are discussed in Interface Commands IEEE 488 Communication optional The IEEE 488 interface is available as an option Baths supplied with this option may be connected to a GPIB type communication bus which allows many instruments to be connected and controlled simultaneously To eliminate noise the GPIB cable should be Digital Communication Interface Interface Commands10 10 5 shielded Setup To use the IEEE 488 interface connect an IEEE 488 standard cable to the back of the bath set the device address and set the transmission termination character To enter the IEEE 488 parameter menu press EXIT while holding down SET then release both buttons to enter the secondary menu Press SET repeatedly until the display reaches PrObe Press UP repeatedly un
21. S Store new set point access vernier 0 00000 Current vernier value Press EXIT and the bath temperature will be displayed again E Return to the temperature display 4 73C Bath temperature display The bath heats or cools until it reaches the new set point temperature Turn off the cooling to reach and control at higher temperatures When setting the set point temperature be careful not to exceed the temperature limit of the bath fluid The over temperature cutout should be correctly set for added safety See Cutout in Chapter 10 To obtain optimum control stability adjust the proportional band as discussed in Proportional Band in Chapter 9 5 1 Chapter 5 Installation Title Page Moving or Uncrating the Bath 5 3 Bath Environment 5 3 Tipping Prevention Bracket Installation 5 3 Installation On A Wood Floor 5 3 7341 Users Guide 5 2 Installation Moving or Uncrating the Bath 5 5 3 Caution Read Chapter 6 BATH USE before placing the bath into service Moving or Uncrating the Bath The bath is equipped with casters and should be rolled It is not equipped with handles and is not designed to
22. Comments EMC Directive Fluke s equipment has been tested to meet the European Electromagnetic Compatibility Directive EMCEMC Directive 89 336 EEC The Declaration of Conformity for your instrument lists the specific standards to which the unit was tested The instrument was designed specifically as a test and measuring device Compliance to the EMC directive is through EN 61326 1 2006 Electrical equipment for measurement control and laboratory use EMC requirements This instrument was tested to Criteria A immunity requirements for Controlled EM Environments per EN61326 2 1 2006 for EM Field from 0 8 2 7 GHz As noted in the IEC 61326 1 the instrument can have varying configurations The instrument was tested in a typical configuration with shielded RS 232 cables Immunity Testing The instrument was tested for laboratory locations Criterion B was used for Radiated RF IEC 61000 4 3 and Voltage dips short interruptions as well as voltage immunity tests IEC 61000 4 11 Criterion C was used for Electrostatic Discharge ESD IEC 61000 4 2 If the instrument is subjected to ESD conditions the instrument may require the user to cycle the power to return to normal operation Emission Testing The instrument fulfills the limit requirements for Class A equipment but does not fulfill the limit requirements for Class B equipment The instrument was not designed to be used in domestic establishments Low Voltage Directive Saf
23. 30 0 0 00385 1 100 000 100 077 Compute ALPHA ALPHA 1 0 00385 80 0 0157 1 0 00385 30 0 0 086 80 0 30 0 1 0 00385 0 0038416 haz008 eps Figure 11 1 Calibration Example 12 1 Chapter 12 Maintenance The calibration instrument has been designed with the utmost care Ease of operation and simplicity of maintenance have been a central theme in the product development Therefore with proper care the instrument should require very little maintenance Avoid operating the instrument in dirty or dusty environments A battery is used to maintain operating parameters in the unit All operating parameters including calibration parameters should be checked on a regular basis to insure accuracy and proper operation of the instrument See the troubleshooting section for the procedure on checking the status of the battery If the outside of the bath becomes soiled it may be wiped clean with a damp cloth and mild detergent Do not use harsh chemicals on the surface which may damage the paint Periodically check the fluid level in the bath to ensure that the level has not dropped If the fluid level is too low the stability may be affected Changes in fluid level are dependent upon several f
24. C below the new set point This permits the maximum heating rate to reach the higher temperatures as quickly as possible The cooling remains off at temperatures above 60 C The automatic cooling mode may not be ideal for all circumstances The automatic mode may be turned off permitting manual control These controls are available through the front panel as described in Operating Parameters in Chapter 9 or through the digital interface as described in Interface Commands and Cooling Control in Chapter 10 The cooling mode control may be set to automatic on or off With these selections the refrigeration is either in automatic as described above always on or always off The hot gas bypass modes are similarly selectable between automatic on or off This system is either in automatic as described above always on low cooling capacity or always off high cooling capacity The following situations benefit by changing cooling modes If the scan mode has been selected and the desired cooling scan requires maximum cooling capacity in a range where the hot gas bypass would normally be on The application requires maximum cooling capacity when the hot gas bypass would normally be on When using the bath at temperatures below 0 C in an ambient of less than 23 C a 7341 Users Guide 8 12 small benefit to stability may be realized by using the hot gas bypass The refrigeration may be beneficially used for short time
25. Fluids used in this bath may produce noxious or toxic fumes under certain circumstances Consult the fluid manufacturer s MSDS Material Safety Data Sheet Proper ventilation and safety precautions must be observed The instrument is equipped with a soft cutout user settable firmware and a hard cutout set at the factory Check the flash point boiling point or other fluid characteristic applicable to the circumstances of the bath operation Ensure that the soft cutout is adjusted to the fluid characteristics of the application As a guideline the soft cutout should be set 10 C to 15 C below the flash point of the bath fluid See Transfer Fluid Chapter 8 for specific information on bath fluids and Cutout Chapter 9 Caution Always operate this instrument at room temperature between 41 F and 122 F 5 C to 50 C Allow sufficient air circulation by leaving at least 6 inches 15 cm of clearance around the instrument When filling the tank ensure the immersion coils are completely covered DO NOT fill above the stir baffle see Figure 4 1 DO NOT overfill the bath Overflowing fluid may damage the electrical system See Bath Preparation and Filling Chapter 5 for specific instructions Read Chapter 6 Bath Use before placing the bath into service DO NOT turn the bath on without fluid in the tank and the heating coils fully immersed See Fluid Expansion Reservoir Chapter 7 for more
26. Problem Causes and Solutions The heater indicator LED stays red but the temperature does not increase The display does not show Cut out nor displays an incorrect bath temperature and the controller otherwise appears to operate normally The problem may be insufficient heating no heating at all or too much cooling The heater power setting being too low especially at higher operating One or more burned out heaters or blown heater fuses may also cause this problem If the heaters seem to be burned out contact an Authorized Service Center see Authorized Service Centers in Chapter 1 for assistance The controller display flashes Cut out and the heater does not operate The display flashes Cut out alternately with the process temperature If the process temperature displayed seems grossly in error consult the following problem The display flashes Cut out and an incorrect process temperature Normally the cutout disconnects power to the heater when the bath temperature exceeds the cutout set point causing the temperature to drop back down to a safe value If the cutout mode is set to AUTO the heater switches back on when the temperature drops If the mode is set to RESET the heater only comes on again when the temperature is reduced and the cutout is manually reset by the operator see Cutout in Chapter 10 Check that the cutout set point is adjusted to 10 or 20
27. When the bath is cooling from one temperature to another below 60 C cooling is at maximum until the bath is within 1 degree C of the set point These conditions are the default conditions but may be altered 7341 Users Guide 10 6 in the following ways The cooling refrigeration may be set to operate in the auto on or off modes See Cooling Mode in Chapter 9 The hot gas bypass or reduced cooling mode may also be set to on off or auto The auto modes allow the bath to operate automatically in the manner described above The cooling on function eliminates this auto feature and the refrigeration is on at all times unless the front panel switch is turned off or until some other menu selection is made The hot gas bypass mode selection works the same way The auto function is the default and active until off or on is selected On means it is always on with no automatic selection and off is always off or cooling always on maximum It may desirable for different reasons to eliminate the automatic functioning therefore these selections are made available either through the front panel or through the digital communications interface Table 10 1 Interface Command Summary Command Description Command Format Command Example Returned Returned Example Acceptable Values Display Temperature Read current set point s etpoint s set 9999 99 C or F set 150 00 C Set current set po
28. cleaning the condensing coil fins Use low pressure compressed air directed at a downward angle to remove lint and dust build up on the condensing fin coils The schedule should be set dependent upon the laboratory environment to ensure that dust does not build up on the fins hampering the efficiency of the bath i e monthly quarterly If a hazardous material is spilt on or inside the equipment the user is responsible for taking the appropriate decontamination steps as outlined by the national safety council with respect to the material MSDS sheets applicable to all fluids used in the 7341 Users Guide 12 2 baths should be kept in close proximity to the instrument If the mains supply cord becomes damaged replace it with a cord of the appropriate gauge wire for the current of the bath If there are any questions call an Authorized Service Center see Authorized Service Centers in Chapter 1 for more information Before using any cleaning or decontamination method except those recommended by Fluke users should check with an Authorized Service Center see Authorized Service Centers in Chapter 1 to be sure that the proposed method will not damage the equipment If the instrument is used in a manner not in accordance with the equipment design the operation of the bath may be impaired or safety hazards may arise The over temperature cutout should be checked every 6 months to see that it is working properly
29. ti 5 Set program set point soak time to n minutes pt n pt 5 0 to 500 Read program control mode pc pc prog OFF or ON prog OFF Set program control mode pc g o s top c ont GO or STOP or CONT Start program pc g o pc g Stop program pc s top pc s Continue program pc c ont pc c Read program function pf pf pf 9 pf 3 Set program function to n pf n pf 2 1 to 4 Secondary Menu Read proportional band setting pr op band pr pr 9 999 pr 0 326 Set proportional band to n pr op band n pr 0 326 Read cutout setting c utout c cu 999 x xxx cu 160 C in Set cutout setting c utout n r ese t Set cutout to n degrees c utout n c 160 Temperature Range Reset cutout now c utout r eset c r Read heater power duty cycle po wer po po 9999 po 1 7341 Users Guide 10 8 Table 10 1 Interface Command Summary cont Command Description Command Format Command Example Returned Returned Example Acceptable Values Configuration Menu Probe Menu Read R0 calibration parameter r 0 r r0 999 999 r0 100 578 Set R0 calibration parameter to n r 0 n r 100 324 98 0 to 104 999 Read ALPHA calibration parameter al pha al al 9 9999999 al 0 0038573 Set ALPHA calibration parameter to n al pha n al 0 0038433 00370 to 0039999 Operating Parameters Menu Read cutout mode cm ode cm cm xxxx cm auto Set cutout m
30. 0 8 5019 100 C v 70 C e NONE 5 7 50 C 0 8 40 C 0 5 70 C 1 71 40 C 0 2 0 0004 0 0011 Methanol 96 C fr 10 C fl cc 12 C 1 3 35 C 0 66 0 C 0 45 20 C 0 810 0 C 0 792 20 C 0 6 0 0005 20 C 0 0014 25 C Water 0 C fr 95 C b NONE 1 25 C 0 4 75 C 1 00 1 00 0 0014 0 0002 25 C Ethylene Glycol 50 5020 30 C fr 90 C b NONE 7 0 C 2 50 C 0 7 100 C 1 05 0 8 0 C 0 001 Mineral Oil No 7 5011 10 C v 166 C fl 168 C 15 75 C 5 125 C 0 87 25 C 0 84 75 C 0 81 125 C 0 48 25 C 0 53 75 C 0 57 125 C 0 00025 25 C 0 0007 50 C 5 25 C Silicone Oil Type 200 05 5010 40 C v 130 C fl cc 133 C 5 25 C 0 92 25 C 0 4 0 00028 25 C 0 00105 1000 25 C 10 150 C Silicone Oil Type 200 10 5012 30 C v 209 C fl cc 211 C 10 25 C 3 135 C 0 934 25 C 0 43 40 C 0 45 100 C 0 482 200 C 0 00032 25 C 0 00108 1000 25 C 50 150 C Silicone Oil Type 200 20 5013 10 C v 230 C fl cc 232 C 20 25 C 0 949 25 C 0 370 40 C 0 393 100 C 0 420 200 C 0 00034 25 C 0 00107 1000 25 C 50 150 C Silicone Oil Type 200 50 5014 30 C v 278 C fl cc 280 C 50 25 C 0 96 25 C 0 4 0 00037 25 C 0 00104 1000 25 C 50 150 C Silicone Oil Type 550 5016 70 C v 230 C fl cc 300 C fl oc 232 C 50 70 C 10 104 C 1 07 25
31. 003 C Eth Gly 50 35 C 0 31 C 0 005 C Eth Gly 50 60 C 0 31 C 0 005 C Eth Gly 50 100 C 0 4 C 0 010 C Oil 200 10cs 35 C 0 6 C 0 004 C Oil 200 10cs 60 C 0 6 C 0 004 C Oil 200 10cs 100 C 0 6 C 0 004 C Oil 710 200 C 0 4 C 0 008 C The proportional band adjustment may be accessed within the secondary menu Press SET and EXIT to enter the secondary menu and show the heater power Then press SET to access the proportional band S E Access heater power in secondary menu 12 Pct Heater power in percent S Access proportional band Pb 0 101C Proportional band setting To change the proportional band press UP or DOWN D Decrement display Pb 0 060C New proportional band setting To accept the new setting and access the cutout set point press SET Pressing EXIT will exit the secondary menu ignoring any changes just made to the proportional band value S Accept the new proportional band setting 7341 Users Guide 9 12 Cutout As a protection against software or hardware fault shorted heater triac or user error the bath is equipped with an adjustable heater cutout device that shuts off power to the heater if the bath temperature exceeds a set value This protects the heater and bath materials from excessive temperatures and most importantly protects the bath fluids from being heated beyond the safe operating temperature
32. Alexandra Terrace 03 16 The Comtech Lobby D 118502 SINGAPORE Phone 65 6799 5588 Telefax 65 6799 5588 E mail antng singa fluke com When contacting these Service Centers for support please have the following information available Model Number Serial Number Voltage Complete description of the problem 2 1 Chapter 2 Introduction The Fluke s 7341 is a compact constant temperature bath useful in temperature calibration and other applications requiring stable temperatures An innovative state of the art solid state temperature controller has been incorporated which maintains the bath temperature with extreme stability The temperature controller uses a micro controller to execute the many operating functions User interface is provided by the 8 digit LED display and four key switches Digital remote communications is standard with an RS 232 and optional with an IEEE 488 interface The 7341 bath was designed to be compact and low cost without compromising performance The 7341 bath operates over a wide temperature range from 40 C to 150 C The refrigeration permits sub ambient temperature control The 7341 features Rapid heating and cooling RS 232 standard and IEEE 488 optional Temperature scan rate control Ramp and soak functions Compact size Eight set point memory Adjustable readout in C or F Automatic refrigeratio
33. August 2012 2012 Fluke Corporation All rights reserved Specifications are subject to change without notice All product names are trademarks of their respective companies 7341 Calibration Bath Users Guide LIMITED WARRANTY AND LIMITATION OF LIABILITY Each Fluke product is warranted to be free from defects in material and workmanship under normal use and service The warranty period is one year and begins on the date of shipment Parts product repairs and services are warranted for 90 days This warranty extends only to the original buyer or end user customer of a Fluke authorized reseller and does not apply to fuses disposable batteries or to any product which in Fluke s opinion has been misused altered neglected contaminated or damaged by accident or abnormal conditions of operation or handling Fluke warrants that software will operate substantially in accordance with its functional specifications for 90 days and that it has been properly recorded on non defective media Fluke does not warrant that software will be error free or operate without interruption Fluke authorized resellers shall extend this warranty on new and unused products to end user customers only but have no authority to extend a greater or different warranty on behalf of Fluke Warranty support is available only if product is purchased through a Fluke authorized sales outlet or Buyer has paid the applicable international price Fluke reserves the right to inv
34. SET after the name of the parameter is displayed The value of the parameter may be changed using the UP and DOWN buttons After the desired value is reached press SET to set the parameter to the new value Press EXIT to skip the parameter ignoring any changes that have been made R0 This probe parameter refers to the resistance of the control probe at 0 C Normally this is set for 100 000 ohms ALPHA This probe parameter refers to the average sensitivity of the probe between 0 and 100 C Normally this is set for 0 00385 C 1 Operating Parameters The operating parameters menu is accessed by pressing UP when the probe menu is displayed The operating parameters menu is indicated by PAr Operating parameters menu Press UP to enter the menu The operating parameters menu contains the cutout reset mode parameter cooling mode and hot gas bypass mode Cutout Reset Mode The cutout reset mode determines whether the cutout resets automatically when the bath temperature drops to a safe value or must be manually reset by the operator The parameter is indicated by CtorSt Cutout reset mode parameter Press SET to access the parameter setting The cutout is set at the factory for manual mode Cto Auto Cutout set for automatic reset 7341 Users Guide 9 14 To change to manual reset mode press UP and then SET Cto rst Cutout set for manual reset Cooling Mode Th
35. Stainless Steel Power 115 VAC 10 60 Hz 16 A 1660 VA 230 VAC 10 50 Hz 8 A 1450 VA optional Note If the voltage is outside 10 the compressor may be damaged Check the back panel label for the correct voltage and frequency prior to energizing the instrument System Fuse 115V 20A 250V slow blow 230V 10A 250V slow blow Volume 4 2 gal 15 9 liters Weight 150 lb 68 kg Size w x f b x h 14 W x 31 D x 42 H 356 x 788 x 1067mm 37 940 mm from floor to tank access opening Safety OVERVOLTAGE Installation CATEGORY II Pollution Degree 2 per IEC 1010 1 Refrigeration R 507 single stage Interface Package RS 232 included IEEE 488 optional Rated at listed 115 V or optional 230 V 7341 Users Guide 3 4 Environmental Conditions Although the instrument has been designed for optimum durability and trouble free operation it must be handled with care The instrument should not be operated in an excessively dusty or dirty environment Maintenance and cleaning recommendations can be found in the Maintenance Section of this manual The instrument operates safely under the following conditions ambient temperature range 5 40 C 41 104 F ambient relative humidity maximum 80 for temperatures lt 31 C decreasing linearly to 50 at 40 C pressure 75kPa 106kPa mains voltage within 10 of nominal vibrations in the calibration environment should
36. The electrical conductivity of water may prevent its use in some applications Water has a limited temperature range from a few degrees above 0 C to a few degrees below 100 C At higher temperatures evaporation becomes significant Water used in the bath should be distilled or deionized to prevent mineral deposits Consider using an algicide chemical in the water to prevent contamination Note Water used at temperatures greater than 75 C 167 F may have stability problems Ethylene Glycol The temperature range of water may be extended by using a solution of one part water and one part ethylene glycol antifreeze The characteristics of the ethylene glycol water solution are similar to water but with higher viscosity Use caution with ethylene glycol since this fluid is very toxic Ethylene glycol must be disposed of properly Mineral Oil Mineral oil or paraffin oil is often used at moderate temperatures above the range of water Mineral oil is relatively inexpensive At lower temperatures mineral oil is quite viscous and control may be poor At higher temperatures vapor emission becomes 7341 Users Guide 8 6 significant The vapors may be dangerous and a fume hood or adequate ventilation system should be used As with most oils mineral oil expands as temperature increases Be careful not to fill the bath too full to avoid overflows when heated see Fluid Expansion Reservoir in Chapter 7 The viscosity and thermal characteristics
37. achieve an accuracy of 0 3 C over the range 10 to 110 C Choosing 30 C and 70 C may allow the bath to have a better accuracy of 0 1 C over the range 25 to 75 C but outside that range the accuracy may be only 0 5 C Measuring the Set point Error The first step in the calibration procedure is to measure the temperature errors including sign at the two calibration temperatures First set the bath to the lower set point tL Wait for the bath to reach the set point and allow 15 minutes to stabilize at that temperature Check the bath stability with the thermometer When both the bath and the thermometer have stabilized measure the actual bath temperature and compute the temperature error errL the actual bath temperature minus the set point temperature For example set the bath to 0 C The bath reaches a measured temperature of 0 3 C giving an error of 0 3 C Next set the bath for the upper set point tH and after stabilizing measure the bath temperature and compute the error errH For example set the bath to 100 C the thermometer measures 100 1 C giving an error of 0 1 C Computing R0 and ALPHA Before computing the new values for R0 and ALPHA the current values must be known The values may be found by either accessing the probe calibration menu from the controller panel or by inquiring through the digital interface The user should keep a record of these values in case they may need to be restored in the f
38. be minimized altitudes less than 2000 meters indoor use only 4 1 Chapter 4 Quick Start Title Page Unpacking 4 3 Set Up 4 3 Power 4 5 Setting the Temperature 4 5 7341 Users Guide 4 2 Quick Start Unpacking 4 4 3 Caution Read Chapter 6 entitled BATH USE before placing the bath in service This chapter gives a brief summary of the steps required to set up and operate the bath This should be used as a general overview and reference and not as a substitute for the remainder of the manual Please read Chapter 5 Installation through Chapter 8 General Operation carefully before operating the bath Unpacking Unpack the bath carefully and inspect it for any damage that may have occurred during shipment If there is shipping damage notify the carrier immediately Verify that all components are present 7341 Bath Access Hole Cover Fluid Expansion Reservoir with Cover User s Guide RS 232 Cable Report of Test Drain Valve 9930 I
39. concerning brownout and over voltage protection Check the back panel label for the correct voltage and frequency prior to energizing the bath 7341 Users Guide 5 6 6 1 Chapter 6 Bath Use Title Page General 6 3 Comparison Calibration 6 3 Calibration of Multiple Probes 6 4 7341 Users Guide 6 2 Bath Use General 6 6 3 Caution Read this chapter entitled BATH USE before placing the bath in service The information in this section is for general information only It is not designed to be the basis for calibration laboratory procedures Each laboratory needs to write their specific procedures General Be sure to select the correct fluid for the temperature range of the calibration Bath fluids should be selected to operate safely with adequate thermal properties to meet the application requirements Also be aware that fluids expand when heated and could overflow the bath if not watched Refer to Chapter 8 General Operation for information specific to fluid selection and to the MSDS sheet specific to the fluid selected Generally baths are set to one temperature and used to calibrate probes only at that single temperature This means
40. for air circulation See Figure 5 1 Screw the bracket securely to the floor Installation Of The Bath Slide the back casters of the bath completely into the tipping bracket Lock the front casters of the bath Check that the bath is securely locked into the tipping bracket by gently pushing on the bath Proceed to fill the bath with the applicable bath fluid after reading the entire Users Guide If you have any questions concerning installation of the tipping prevention bracket please contact a Fluke Authorized Service Center Dry out Period If this equipment is used in a manner not specified by the manufacturer the protection provided by the equipment may be impaired Before initial use or after transport or after storage in humid or semi humid environments or anytime the bath has not been energized for more than 10 days the instrument needs to be energized for a dry out period of 2 hours before it can be assumed to meet all of the safety requirements of the IEC 1010 1 If the product is wet or has been in a wet environment take necessary measures to remove moisture prior to Installation Bath Preparation and Filling 5 5 5 applying power such as storage in a low humidity temperature chamber operating at 50 C for 4 hour or more Bath Preparation and Filling Caution Avoid spilling fluid over the control panel Immediately clean up any spilling Cover the panel if necessary during filling DO NOT overfill
41. of mineral oil is poorer than water so temperature stability will not be as good Mineral oil has very low electrical conductivity Use caution with mineral oil since it is flammable and may also cause serious injury if inhaled or ingested Silicone Oil Silicone oils are available which offer a much wider operating temperature range than mineral oil Like most oils silicone oils have temperature control characteristics which are somewhat poorer than water The viscosity changes significantly with temperature and thermal expansion also occurs These oils have very high electrical resistivity Silicone oils are fairly safe and non toxic but can be fairly expensive Fluid Characteristics Charts Caution Due to the unique properties of silicone oils and their ability to migrate and creep through seals adequate ventilation must be used to prevent oil vapors from creating an oily dirty environment Oily dirty environments reduce the lifetime of the instruments electrical components Table 8 1 and Figure 8 1 have been created to provide help in selecting a heat exchange fluid media for your constant temperature bath These charts provide both a visual and numerical representation of most of the physical qualities important in making a selection The list is not all inclusive There may be other useful fluids not shown in this listing The charts include information on a variety of fluids which are often used as heat transfer fluid in baths
42. oily dirty environment Tipping Prevention Bracket Installation In order to create the safest possible conditions under use your bath comes equipped with a tipping prevention bracket The installation of the bracket is required for compliance with the international safety standard IEC 1010 1 see Stability in Chapter 7 that applies to the stability of the bath under normal operating conditions Installation On A Wood Floor The wood floor installation kit includes lag bolts Drill three 1 8 inch x 1 inch deep approximately 3 mm x 25 5 mm pilot holes using the tipping bracket to mark the hole placement Use the lag bolts to install the bracket to the floor Ensure that the bracket is installed in such a way that the bath will have a minimum 6 inches of clearance for air circulation See Figure 5 1 Screw the bracket securely to the floor 7341 Users Guide 5 4 Front Caster Slots 8 5 21 6 cm Wall haz002 eps Figure 5 1 Tipping Prevention Bracket Installation Installation On a Concrete Floor Using a concrete drill and concrete drill bit drill three inch x 1 inch deep approximately 6 5 mm x 32 mm holes in the concrete floor using the bracket to mark the hole placement Drop the flare anchor bolt into the hole Tightening the screw expands the anchor in the drilled hole and secures the tipping bracket Ensure that the bracket is installed in such a way that the bath will have a minimum of 6 inches of clearance
43. on au to On Off Auto Set HGb mode to Off hg b of f hg of Set HGb mode to On hg b on hg on Set HGb mode to Auto hg b a uto hg au Read low set point limit value tl ow tl tl 999 tl 40 Set low set point limit to n tl ow n tl 40 60 to 20 Read high set point limit value th igh th th 999 th 150 Set high set point limit to n th igh n th 150 150 to 30 Miscellaneous not on menus Read all extended parameters all all list of extended parameters Read firmware version number ver sion ver ver 9999 9 99 ver 7341 1 00 Read all operating parameters all all list of operating parameters Read structure of all commands h elp h list of commands Legend Optional Command data Returns either information n Numeric data supplied by user 9 Numeric data returned to user x Character data returned to user Note When DUPLEX is set to FULL and a command is sent to READ the command is returned followed by a carriage return and linefeed Then the value is returned as indicated in the RETURNED column 7341 Users Guide 10 10 11 1 Chapter 11 Calibration Procedure Title Page Calibration Points 11 3 Measuring the Set point Error 11 3 Computing
44. press SET E Return to temperature display Proportional Band In a proportional controller such as this the heater output power is proportional to the bath temperature over a limited range of temperatures around the set point This range of temperature is called the proportional band At the bottom of the proportional band the heater output is 100 At the top of the proportional band the heater output is 0 Thus as the bath temperature rises the heater power is reduced which consequently tends to lower the temperature back down In this way the temperature is maintained at a fairly constant temperature The temperature stability of the bath depends on the width of the proportional band see Figure 9 2 If the band is too wide the bath temperature deviates excessively from the set point due to varying external conditions This is because the power output changes very little with temperature and the controller cannot respond very well to changing conditions or noise in the system If the proportional band is too narrow the bath temperature may swing back and forth because the controller overreacts to temperature variations For best control stability the proportional band must be set for the optimum width haz006 eps Figure 9 2 Bath Temperature Fluctuation At Various Proportional Band Settings The optimum proportional band width depends on several factors among which are fluid volume fluid characteristics viscosity specific heat
45. resistivity describes how well the fluid insulates against the flow of electric current In some applications such as measuring the resistance of bare temperature sensors it may be important that little or no electrical leakage occur through the fluid In such conditions choose a fluid with very high electrical resistivity Fluid Lifetime Many fluids degrade over time because of vaporization water absorption gelling or chemical break down Often the degradation becomes significant near the upper temperature limit of the fluid substantially reducing the fluid s lifetime Safety When choosing a fluid always consider the safety issues associated Obviously where there are extreme temperatures there can be danger to personnel and equipment Fluids may also be hazardous for other reasons Some fluids may be considered toxic Contact with eyes skin or inhalation of vapors may cause injury A proper fume hood or General Operation Heat Transfer Fluid 8 8 5 adequate ventilation system must be used if hazardous or bothersome vapors are produced Warning Fluids at high temperatures may pose danger from BURNS FIRE and TOXIC FUMES Use appropriate caution and safety equipment Fluids may be flammable and require special fire safety equipment and procedures An important characteristic of the fluid to consider is the flash point The flash point is the temperature at which there is sufficient vapor given off so that when there is
46. switching the heater on for a certain amount of time using a solid state relay The front panel red green control indicator shows the state of the heater The control indicator glows red when the heater is on and green when the heater is off The indicator pulses at a constant rate when the bath is maintaining a stable temperature Temperature Controller Fluke s unique hybrid digital analog temperature controller controls the bath temperature The controller offers the tight control stability of an analog temperature controller as well as the flexibility and programmability of a digital controller The bath temperature is monitored using a platinum resistance sensor as the control probe The signal is electronically compared with the programmable reference signal amplified and then passed to a pulse width modulator circuit that controls the amount of power applied to the bath heater The bath is operable within the temperature range given in the specifications For protection against a solid state relay failure or other circuit failure the micro controller automatically turns off the heater with a second mechanical relay anytime the bath temperature is more than a certain amount above the set point temperature In addition to this protection the controller is also equipped with a separate thermocouple temperature monitoring circuit that shuts off the heater if the temperature exceeds the cutout set point The controller allows the operator
47. temperatures could ignite the flammable material Overhead clearance is required Do not place the instrument under a cabinet or other structure Always leave enough clearance to allow for safe and easy insertion and removal of probes Before You Start Safety Information 1 1 5 The instrument is intended for indoor use only The bath is a precision instrument Although it has been designed for optimum durability and trouble free operation it must be handled with care Position the bath before the tank is filled with fluid by rolling it into place DO NOT attempt to lift the bath Due to the weight of the compressor it may require two people to safely move the bath The area containing the compressor will be heavier than the rest of the bath DO NOT move a bath filled with fluid see Moving or Uncrating the Bath in Chapter 5 BURN HAZARD Extremely cold temperatures may be present in this equipment Freezer burns and frostbite may result if personnel fail to observe safety precautions High temperatures may be present in this equipment Fires and severe burns may result if personnel fail to observe safety precautions The drain tube and dust cover of the Fluid Expansion Reservoir may be hot Handle them carefully and always be sure the drain tube is fully inserted into the elbow of the dust cover The drain tube of the Fluid Expansion Reservoir is not designed to handle large flow rates en
48. that the type of bath fluid does not have to change Additionally the bath can be left energized reducing the stress on the system The bath generates extreme temperatures Precautions must be taken to prevent personal injury or damage to objects Probes may be extremely hot or cold when removed from the bath Cautiously handle probes to prevent personal injury Carefully place probes on a heat cold resistant surface or rack until they are at room temperature It is advisable to wipe the probe with a clean soft cloth or paper towel before inserting it into another bath This prevents the mixing of fluids from one bath to another If the probe has been calibrated in liquid salt carefully wash the probe in warm water and dry completely before transferring it to another fluid Always be sure that the probe is completely dry before inserting it into a hot fluid Some high temperature fluids react violently to water or other liquid mediums Be aware that cleaning the probe can be dangerous if the probe has not cooled to room temperature Additionally high temperature fluids may ignite the paper towels if the probe has not been sufficiently cooled For optimum accuracy and stability allow the bath adequate stabilization time after reaching the set point temperature Comparison Calibration Comparison calibration involves testing a probe unit under test UUT against a reference probe After inserting the probes to be calibrated into the bath allow su
49. Because of the temperature range some fluids may not be useful with your bath Limitations and Disclaimer The information given in this manual regarding fluids is intended only to be used as a general guide in choosing a fluid Though every effort has been made to provide correct information we cannot guarantee accuracy of data or assure suitability of a fluid for a particular application Specifications may change and sources sometimes offer differing information Fluke cannot be liable for any personal injury or damage to equipment product or facilities resulting from the use of these fluids The user of the bath is responsible for collecting correct information exercising proper judgment and insuring safe operation Operating near the limits of certain properties such as the flash point or viscosity can compromise safety or performance Your company s safety policies regarding flash points toxicity and such issues must be considered You are responsible for reading the MSDS material safety data sheets and acting accordingly General Operation Heat Transfer Fluid 8 8 7 Table 8 1 Various Bath Fluids and Their Properties Fluid PN Lower Temp Limit Upper Temp Limit Flash Point Viscosity centisto kes Specific Gravity Specific Heat cal g C Thermal Conductivity cal s cm C Thermal Expansion cm cm C Resistivity 1012 cm Halocarb on
50. C Well temperature S U Access program menu ProG Program menu Press SET to enter the program menu S Enter program menu Number of Program Set points The first parameter in the program menu is the number of set points to cycle through Up to 8 set points can be used in a ramp and soak program These set points are independent from the programmable set points described in Section Programmable Set points 7341 Users Guide 9 8 Pn 8 Number of program set points Use the UP or DOWN buttons to change the number from 2 to 8 Pn 3 New number of program set points Press SET to continue Press EXIT to ignore any changes and to continue S Save new setting Set points The next parameters are the program set points 1 50 0 First set point Use the UP or DOWN buttons to select any of the set points 3 30 0 Third set point Press SET to be able to change the set point C 30 0 Set point value Use UP and DOWN to change the set point value C 40 00 New set point value Press SET to save the new set point value The other set points can also be set in the same manner Once the set points are programmed as desired press EXIT to continue E Continue to next menu function Program Soak Time The next parameter in the program menu is the soak time This is the time in minutes that each program set point is maintained after settling before pr
51. C 0 358 40 C 0 386 100 C 0 433 200 C 0 00035 25 C 0 00075 100 25 C 1 150 C Silicone Oil Type 710 5017 80 C v 300 C fl oc 302 C 50 80 C 7 204 C 1 11 25 C 0 363 40 C 0 454 100 C 0 505 200 C 0 00035 25 C 0 00077 100 25 C 1 150 C Silicone Oil Type 210 H 66 C v 313 C fl oc 315 C 50 66 C 14 204 C 0 96 25 C 0 34 100 C 0 0003 0 00095 100 25 C 1 150 C Heat Transfer Salt 5001 180 C fr 550 C NONE 34 150 C 6 5 300 C 2 4 500 C 2 0 150 C 1 9 300 C 1 7 500 C 0 33 0 0014 0 00041 1 7 cm3 Limiting Factors b boiling point e high evaporation fl flash point fr freeze point v viscosity Flash point test oc open cup cc closed cup Very low water solubility ice will form as a slush from condensation below freezing 7341 Users Guide 8 8 About the Chart The fluid chart visually illustrates some of the important qualities of the fluids shown Temperature Range The temperature scale is shown in degrees Celsius The shaded bands indicate the fluids general range of application Qualities including pour point freeze point important viscosity points flash point boiling point and others may be shown Freezing Point The freezing point of a fluid is an obvious limitation to stirring As the freezing point is approached high viscosity may also limit performance General Operation Heat Transfer Fluid 8 8 9
52. C above the maximum bath operating temperature and that the cutout mode is set as desired If the cutout activates when the bath temperature is well below the cutout set point or the cutout does not reset when the bath temperature drops and it is manually reset then the cutout circuitry or the cutout thermocouple sensor may be faulty or disconnected Contact an Authorized Service Center see Authorized Service Centers in Chapter 1 for assistance The display flashes cutout and an incorrect process temperature The problem may be that the controller s voltmeter circuit is not functioning properly A problem could exist with the memory back up battery If the battery voltage is insufficient to maintain the memory data may become scrambled causing problems A nearby large static discharge may also affect data in memory Verify that the parameters on the Report of Test are accurate Cycle the power off disconnect the bath from AC and then restart the bath 7341 Users Guide 13 4 If the problem reoccurs the battery should be replaced Contact an Authorized Service Center see Authorized Service Centers in Chapter 1 for assistance If initializing the memory does not remedy the problem there may be a failed electronic component Contact an Authorized Service Center see Authorized Service Centers in Chapter 1 for assistance The controller may need to be reset Perform the following Factory Rese
53. EXIT button If the cutout is still in the over temperature fault condition the display continues to flash cutout The bath temperature must drop a few degrees below the cutout set point before the cutout can be reset Temperature Set point The bath temperature can be set to any value within the range and with resolution as given in the specifications The operator must know the temperature range of the particular fluid used in the bath and the bath should only be operated well below the upper temperature limit of the fluid In addition the cutout temperature should also be set below the upper limit of the fluid Setting the bath temperature involves three steps 1 selecting the set point memory 2 adjusting the set point value and 3 adjusting the vernier if desired Programmable Set points The controller stores 8 set point temperatures in memory The set points can be quickly recalled to conveniently set the bath to a previously programmed temperature set point To set the bath temperature one must first select the set point memory This function is accessed from the temperature display function by pressing SET The number of the set point memory currently being used is shown at the left on the display followed by the current set point value 25 00C Bath temperature in degrees Celsius S Access set point memory 1 25 0 1 25 0 C currently used To change the set point memory press UP or DOWN U Incre
54. G BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE FLUKE SHALL NOT BE LIABLE FOR ANY SPECIAL INDIRECT INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSSES INCLUDING LOSS OF DATA ARISING FROM ANY CAUSE OR THEORY Since some countries or states do not allow limitation of the term of an implied warranty or exclusion or limitation of incidental or consequential damages the limitations and exclusions of this warranty may not apply to every buyer If any provision of this Warranty is held invalid or unenforceable by a court or other decision maker of competent jurisdiction such holding will not affect the validity or enforceability of any other provision Fluke Corporation P O Box 9090 Everett WA 98206 9090 U S A Fluke Europe B V P O Box 1186 5602 BD Eindhoven The Netherlands 11 99 To register your product online visit register fluke com i Table of Contents Chapter Title Page 1 Before You Start 1 1 Symbols Used 1 3 Safety Information 1 4 Authorized Service Centers 1 7 2 Introduction
55. In order to check the user selected cutout follow the controller directions in Reset Cutout in Chapter 9 for setting the cutout Both the manual and the auto reset option of the cutout should be checked Set the bath temperature higher than the cutout Check to see if the display flashes cutout and if the temperature is decreasing Note When checking the over temperature cutout be sure that the temperature limits of the bath fluid are not exceeded Exceeding the temperature limits of the bath fluid could cause harm to the operator lab and instrument When using silicon oil the bath will require periodic maintenance The silicon oil will condense on the bath during normal operation due to the outgasing of the oil How often and how long the bath is operated at higher temperatures determines how often the maintenance will have to be performed Simply wipe down the oily areas of the bath with a mild degreaser such as 409 Do not spray the degreaser directly on the bath Spray the degreaser on a cloth and wipe the bath down with the cloth Repeat the process as often as necessary to keep the oil from collecting on the bath If oil is allowed to collect on the bath it may run into the bath and collect on the interior of the bath causing internal damage that may affect the lifetime of the instrument 13 1 Chapter 13 Troubleshooting Title Page Troubleshooting
56. R0 and ALPHA 11 3 Calibration Example 11 4 7341 Users Guide 11 2 Calibration Procedure Calibration Points11 11 3 In some instances the user may want to calibrate the bath to improve the temperature set point accuracy Calibration is done by adjusting the controller probe calibration constants R0 and ALPHA so that the temperature of the bath as measured with a standard thermometer agrees more closely with the bath set point The thermometer used must be able to measure the bath fluid temperature with higher accuracy than the desired accuracy of the bath By using a good thermometer and carefully following procedure the bath can be calibrated to an accuracy of better than 0 2 C over a range of 100 degrees Calibration Points In calibrating the bath R0 and ALPHA are adjusted to minimize the set point error at each of two different bath temperatures Any two reasonably separated bath temperatures may be used for the calibration however best results will be obtained when using bath temperatures which are just within the most useful operating range of the bath The further apart the calibration temperatures the greater the calibrated temperature range and the calibration error If for instance 0 C and 100 C are chosen as the calibration temperatures the bath may
57. The Model 7341 Bath is not provided with a fluid Various fluids are available from Hart and other sources Depending on the desired temperature range any of the following fluids as well as others may be used in the bath Water Ethylene glycol water Mineral oil Silicone oil Ethanol Fluids are discussed in detail in Heat Transfer Fluid in Chapter 8 Remove any access hole cover from the bath and check the tank for foreign matter dirt remnant packing material etc Fill the bath with clean unpolluted fluid Fill the bath carefully through the large rectangular access hole to a level that will allow for stirring and thermal expansion Thermal Expansion in Chapter 8 explains fluid expansion Caution DO NOT turn on the bath without fluid in the tank and the heating coils fully immersed See Fluid Expansion Reservoir in Chapter 7 on how to use the fluid expansion reservoir Be sure the fluid expansion reservoir is properly installed checking to insure it is clean and free of foreign matter Carefully monitor the bath fluid level as the bath temperature rises to prevent excessive overflow or splashing Remove excess hot fluid if necessary with caution Power With the bath power switch off plug the bath into an AC mains outlet of the appropriate voltage frequency and current capacity Refer to Specifications in Chapter 3 for power details Refer to and read the CAUTION at the front of the manual
58. actors specific to the conditions in which the equipment is used A schedule cannot be outlined to meet each set of conditions Therefore the bath should be checked weekly and adjustments made as required Warning Before servicing the instrument disconnect the power mains Periodically remove the top cover of the bath and wipe out oil around the outside of the gasket In order to do this remove the four screws on the top surface and the two screws at the rear of the bath Lift the cover just far enough to wipe out the collected oil Heat transfer medium lifetime is dependent upon the type of medium and the conditions of use The fluid should be checked at least every month for the first year and regularly thereafter This fluid check provides a baseline for knowledge of bath operation with clean usable fluid Once some fluids have become compromised the break down can occur rapidly Particular attention should be paid to the viscosity of the fluid A significant change in the viscosity can indicate that the fluid is contaminated being used outside of its temperature limits contains ice particles or is close to a chemical breakdown Once data has been gathered a specific maintenance schedule can be outlined for the instrument Refer to Chapter 8 General Operation for more information about the different types of fluids used in calibration baths Depending on the cleanliness of the environment a schedule should be set for
59. adequate oxygen present and an ignition source is applied the vapor will ignite This does not necessarily mean that fire will be sustained at the flash point The flash point may be either of the open cup or closed cup type Either condition may occur in a bath situation The open cup flash point is measured under the condition of vapors escaping the tank The closed cup flash point is measured with the vapors being contained within the tank Since oxygen and an ignition source is less available inside the tank the closed cup flash point will be lower than the open cup flash point Environmentally hazardous fluids require special disposal according to applicable federal or local laws after use Cost Cost of bath fluids may vary greatly from cents per gallon for water to hundreds of dollars per gallon for synthetic oils Cost may be an important consideration when choosing a fluid Commonly Used Fluids Below is a description of some of the more commonly used fluids and their characteristics Water Water is often used because of its very low cost its availability and its excellent temperature control characteristics Water has very low viscosity and good thermal conductivity and heat capacity which make it among the best fluids for good control stability at lower temperatures Temperature stability is much poorer at higher temperatures because water condenses on the lid cools and drips into the bath Water is safe and relatively inert
60. ations transmission rate The baud rate parameter is indicated by bAUd Serial baud rate parameter Press SET to choose to set the baud rate The current baud rate value will then be displayed 1200b Current baud rate The baud rate of the bath serial communications may be programmed to 300 600 1200 or 2400 baud Use UP or DOWN to change the baud rate value 2400b New baud rate Press SET to set the baud rate to the new value or EXIT to abort the operation and skip to the next parameter in the menu Sample Period The sample period is the next parameter in the serial interface parameter menu The sample period is the time period in seconds between temperature measurements transmitted from the serial interface If the sample rate is set to 5 the bath transmits the current measurement over the serial interface approximately every five seconds The automatic sampling is disabled with a sample period of 0 The sample period is indicated by sanpLe Serial sample period parameter Press SET to choose to set the sample period The current sample period value will be displayed sa 1 Current sample period seconds Adjust the value with UP or DOWN and then use SET to set the sample rate to the displayed value sa 60 New sample period 7341 Users Guide 9 16 Duplex Mode The next parameter is the duplex mode The duplex mode may be set to full duplex or half duplex With full d
61. ausing the fluid to thicken Replace at the first sign of increasing viscosity Stirring Stirring the bath fluid is very important for stable temperature control The fluid must be mixed well for good temperature uniformity and fast controller response The stirrer is precisely adjusted for optimum performance Power Power to the bath is provided by an AC mains supply Refer to Specifications in Chapter 3 for power details Refer to and read the CAUTION at the front of the manual concerning brownout and over voltage protection Check the back panel label for the correct voltage and frequency prior to energizing the bath Power to the bath passes through a filter to prevent switching spikes from being transmitted to other equipment To turn on the bath press the control panel power switch to the ON position The stirring motor will turn on the LED display will begin to show the bath temperature and the heater will turn on or off until the bath temperature reaches the programmed set point When powered on the control panel display will briefly show a four digit number This number indicates the number of times power has been applied to the bath Also briefly displayed is data which indicates the controller hardware configuration This data is used in some circumstances for diagnostic purposes Heater The temperature controller precisely controls the bath heater to maintain a constant bath temperature Power is controlled by periodically
62. bath and reduces energy consumption The HGb system is normally in the automatic mode which switches on reducing capacity when at set points above 0 C When the bath is scanning to lower temperatures greater than 2 C below the starting temperature the HGb turns off for full cooling capacity for all temperatures below the maximum refrigeration limit even above 0 C There are three HGb modes Auto On or Off Normally HGb mode is set to Auto mode If for some reason the automatic mode is undesirable the HGb mode can be set to always On or Off The parameter is indicated by Hgb HGb mode parameter Press SET to access the parameter setting Auto HGb mode set for automatic To change to On or Off mode press DOWN until the desired mode appears and then press SET Controller Operation Serial Interface Parameters 9 9 15 On HGb mode set to on OFF HGb mode set to off Serial Interface Parameters The serial interface menu is accessed by pressing UP from the operating parameters menu The serial RS 232 interface parameters menu is indicated by SErIAL Serial RS 232 interface parameters menu The serial interface parameters menu contains parameters which determine the operation of the serial interface The parameters in the menu are baud rate sample period duplex mode and linefeed Baud Rate The baud rate is the first parameter in the menu The baud rate setting determines the serial communic
63. baud rate value Press SET to set the baud to the new value or EXIT to abort the operation and skip to the next parameter in the menu Sample Period The sample period is the next parameter in the menu and prompted with SAnpLE The sample period is the time period in seconds between temperature measurements transmitted from the serial interface If the sample period is set to 5 the bath transmits the current measurement over the serial interface approximately every five seconds The automatic sampling is disabled with a sample period of 0 Press SET to choose to set the sample period Adjust the period with UP or DOWN Press SET to set the sample period to the new value or EXIT to abort and skip to the next parameter Duplex Mode The next parameter is the duplex mode indicated with dUPL The duplex mode may be set to half duplex HALF or full duplex FULL With full duplex any commands received by the bath via the serial interface are executed and immediately echoed or transmitted back to the device of origin With half duplex the commands are executed but not echoed The default setting is full duplex The mode may be changed using UP or DOWN Press SET to save the new setting or EXIT to abort and skip to the next parameter Linefeed The final parameter in the serial interface menu is the linefeed mode This parameter enables On or disables
64. be lifted When uncrating the bath remove all of the accessories from the packing foam around the bath Remove the pre formed foam Gently ease the bath from the crate using the casters to roll the bath If it is required to lift the bath slightly to release it from the crate two people should carefully slide their hands under the bath and gently lift the bath only enough to clear the packing foam and roll the bath from the crate The area containing the compressor will be heavier than the rest of the bath If it is required to move the bath after installation empty the bath of fluid DO NOT move a bath filled with fluid Unlock the casters and roll the bath Do not attempt to carry the bath It is tall and heavy and is not provided with handles Personal injury or damage to the bath may occur Bath Environment The Model 7341 Bath is a precision instrument which should be located in an appropriate environment The location should be free of drafts extreme temperatures and temperature changes dirt etc The surface where the bath is placed must be level Provide at least 6 inches 15 cm of clearance around the instrument to allow sufficient air circulation The top surface of the bath may become hot at high temperatures Beware of the danger of accidental fluid spills A fume hood or other adequate ventilation system should be used to remove any vapors given off by hot bath fluid Silicone oils require additional ventilation to prevent an
65. controller alternately heats for a while then cools The bath is not stable and the duty cycle is not constant The proportional band being too narrow typically causes this oscillation Increase the width of the proportional band until the temperature stabilizes as discussed in Proportional Band in Chapter 9 The controller erratically heats then cools control is unstable If both the bath temperature and output power do not vary periodically but in a very erratic manner the problem may be excess noise in the system Noise due to the control sensor should be less than 0 001 C However if the probe has been damaged or has developed an intermittent short erratic behavior may exist The probe is located inside the stirrer motor cover Check for a damaged probe or poor connection between the probe and bath Intermittent shorts in the heater or controller electronic circuitry may also be a possible cause Contact an Authorized Service Center see Authorized Service Centers in Chapter 1 for assistance The bath does not achieve low temperatures Too much heating or not enough cooling can cause this problem Check that the control indicator glows green showing that the controller is attempting to cool The heaters may be disabled as a test by temporarily removing the heater fuses Insufficient cooling may be caused by lack of refrigerant Contact an Authorized Service Center for assistance 7341 Users Guide 13 6
66. countered by overfilling the tank It is intended for expanding fluid rates from heating only Fill tank only until the level reaches the top of the baffle see Figure 4 1 ELECTRICAL HAZARD These guidelines must be followed to ensure that the safety mechanisms in this instrument will operate properly This instrument must be plugged into a 115 VAC 60Hz 230 VAC 50Hz optional AC only electric outlet The power cord of the instrument is equipped with a three pronged grounding plug for your protection against electrical shock hazards It must be plugged directly into a properly grounded three prong receptacle The receptacle must be installed in accordance with local codes and ordinances Consult a qualified electrician DO NOT use an extension cord or adapter plug DO use a ground fault interrupt device This instrument contains a fluid A ground fault device is advised in case fluid is present in the electrical system and could cause an electrical shock Always replace the power cord with an approved cord of the correct rating and type If you have questions contact an Authorized Service Center see Authorized Service Centers in Chapter 1 High voltage is used in the operation of this equipment Severe injury or death may result if personnel fail to observe the safety precautions Before working inside the equipment turn off the power and disconnect the power cord 7341 Users Guide 1 6 BATH FLUIDS
67. cover Other fixtures to hold the probes can be designed The object is to keep the reference probe and the probe s to be calibrated as closely grouped as possible in the working area of the bath Bath stability is maximized when the bath working area is kept covered In preparing to use the bath for calibration start by Placing the reference probe in the bath working area Placing the probe to be calibrated the UUT in the bath working area as close as feasibly possible to the reference probe but not touching the bath tank surface areas Calibration of Multiple Probes Fully loading the bath with probes increases the time required for the temperature to stabilize after inserting the probes Using the reference probe as the guide ensures that the temperature has stabilized before starting the calibration 7 1 Chapter 7 Parts and Controls Title Page Front Control Panel 7 3 Back Panel 7 3 Fluid Expansion Reservoir 7 3 7341 Users Guide 7 2 Parts and Controls Front Control Panel 7 7 3 Front Control Panel The following controls and indicators are present on the controller front panel see Figure 7 1 1 the digital LED disp
68. ctory settings A list of these constants and their settings are supplied to the user on the Report of Test with the manual CAUTION DO NOT change the values of the instrument calibration constants from the factory set values The correct setting of these parameters is important to the safety and proper operation of the instrument The calibration parameters menu is indicated by CAL Calibration parameters menu Press SET five times to enter the menu CTO Parameter CTO sets the calibration of the over temperature cutout This is not adjustable by software but is adjusted with an internal potentiometer This parameter is set at the factory CO and CG These parameters calibrate the accuracy of the instrument set point These are programmed at the factory Do not alter the value of these parameters If the user desires to calibrate the bath for improved accuracy adjust R0 and ALPHA according to the procedure given in Chapter 11 Calibration Procedure H and L These parameters set the upper and lower set point limits of the bath Note A high limit H setting below the flash point of the fluid in the bath is highly recommended HGbt 7341 Users Guide 9 18 This parameter is the temperature where the hot gas bypass activates This parameter is factory set To insure the bath s best performance without damaging its compressor DO NOT alter the value of this parameter 10 1 Chapter 10 Digital Communication In
69. d Few fluids work well throughout the entire temperature range of the bath The temperature at which the bath is operated must always be within the safe and useful temperature range of the fluid used The lower temperature range of the fluid is determined either by the freeze point of the fluid or the temperature at which the viscosity becomes too great The upper temperature is usually limited by vaporization flammability or chemical breakdown of the fluid Vaporization of the fluid at higher temperatures may adversely affect temperature stability because of cool condensed fluid dripping into the bath from the lid The bath temperature should be limited by setting the safety cutout see Cutout in Chapter 9 or the high limit see Calibration Parameters in Chapter 9 so that the bath temperature cannot exceed the safe operating temperature limit of the fluid Viscosity Viscosity is a measure of the thickness of a fluid or how easily it can be poured and mixed Viscosity affects the temperature uniformity and stability of the bath With lower viscosity fluid mixing is better This creates a more uniform temperature throughout the bath This improves the bath response time allowing it to maintain a more constant temperature For good control the viscosity should be less than 10 centistokes 50 centistokes is the practical upper limit of allowable viscosity Viscosity greater than this causes very poor control stability because of poor stirring and ma
70. d cool down The cooling shuts off automatically above 60 C Manually turn off the refrigeration at temperatures where it has been determined to be unnecessary See Refrigeration Chapter 8 Cooling Mode Chapter 9 and Hot Gas Bypass Mode Chapter 9 Back Panel On the back of the bath are the system fuses power cord high low voltage indicator drain serial port IEEE 488 port if installed and the fluid expansion reservoir Fluid Expansion Reservoir The fluid expansion reservoir is attached to the rear panel of the bath Its purpose is to 7341 Users Guide 7 4 receive excess fluid expanded in the process of heating the bath to higher temperatures Any liquid will expand when heated To prevent the bath from overflowing when the fluid expands the excess fluid must be removed either prior to heating or by allowing it to drain out of the bath tank Note The fluid level must never be below the heating elements This bath has an overflow tube attached to the bath tank that extends to the rear of the bath and drains into the fluid expansion reservoir The reservoir has enough capacity to cover a large range of thermal expansion rates for different fluids No attempt must be made to plug the overflow tube to prevent fluid from draining Do not attempt to fill the bath to a level higher than the overflow tube level The fluid expansion reservoir is stainless steel with an aluminum heat shield to prevent touching when the tank is
71. dangerous to permit the fluid to overflow the tank It may also cause loss of valuable bath fluid Excessive thermal expansion may also be undesirable in applications where constant liquid level is important Thermal expansion coefficients of several fluids are shown in Table 8 1 Fluid manufacturers can also provide this information The thermal expansion coefficients are shown in units of cm cm C However the values are the same for any unit of length Divide the value by 1 8 for F coefficients The following equation may be used to find the desired depth DE DS K TE TS 1 Or DS DE K TE TS 1 where DE The Maximum Fill Depth Where K Expansion coefficient TE Ending temperature TS Starting temperature DE Ending depth DS Starting depth The maximum fill depth is typically 0 5 to 0 8 inches below the level of the gasket at the top of the bath tank not the top of the bath lid Judgment must be made with different stirring arrangements to prevent splashing on the gasket or lid of the bath Example The final depth of Dow Corning 710 silicone oil in the bath tank is to be 9 2 inches when heated from 25 to 300 C What should the starting depth be Expansion coefficient for 710 oil on Table 2 K 0 00077 inch inch C Ending temperature TE 300 C Starting temperature TS 25 C Ending depth DE 9 2 inches DS 9 2 0 00077 300 25 1 7 59 inches Electrical Resistivity Electrical
72. degrees of the selected units C or F 0 00000 Current vernier value in C To adjust the vernier press UP or DOWN Unlike most functions the vernier setting has immediate effect as the vernier is adjusted SET need not be pressed This allows the bath temperature to be continually adjusted as it is displayed U Increment display 0 00090 New vernier setting Next press EXIT to return to the temperature display or SET to access the temperature scale units selection S Access scale units Scan The scan rate can be set and enabled so that when the set point is changed the instrument heats or cools at a specified rate degrees per minute until it reaches the new set point With the scan disabled the instrument heats or cools at the maximum possible rate Scan Control The scan is controlled with the scan on off function that appears in the main menu after the set point function scAn OFF Scan function off Press UP or DOWN to toggle the scan on or off scAn On Scan function on Press SET to accept the present setting and continue S Accept scan setting lScan Rate The next function in the main menu is the scan rate The scan rate can be set from 0 001 to 5 0 C min The maximum scan rate however is actually limited by the natural heating or cooling rate of the instrument This is typically less than 2 5 C min especially when Controller Operation Temperature Scale Units 9
73. e configured to use the same address as the external communicating device The address is indicated by AddrEss IEEE 488 interface address Press SET to access the address setting Add 22 Current IEEE 488 interface address Adjust the value with UP or DOWN and then use SET to set the address to the displayed value Add 15 New IEEE 488 interface address Controller Operation Calibration Parameters 9 9 17 Transmission Termination The transmission termination character can be set to carriage return only linefeed only or carriage return and linefeed Regardless of the option selected the instrument will interpret either a carriage return or a linefeed as a command termination during reception The termination parameter is indicated with eOS IEEE 488 termination Press SET to access the termination setting e Cr Present IEEE 488 termination Use UP or DOWN to change the selection e LF New termination selection Use SET to save the new selection Calibration Parameters The operator of the bath controller has access to a number of the instrument calibration constants namely CTO C0 CG H L and HGbt These values are set at the factory and must not be altered The correct values are important to the accuracy and proper and safe operation of the bath These parameters should not be adjusted In the event the controller s memory fails the user may restore these values to the fa
74. e cooling mode determines whether refrigeration is in Auto mode On or Off Normally the cooling mode is set to Auto mode In the Auto mode the refrigeration is On below approximately 60 C Note If the fluid is cooling from above 60 C the refrigeration turns on at approximately 59 C If the fluid is heating from below 60 C the refrigeration shuts off at 60 C If the set point is more than 5 C higher than the current bath temperature the refrigeration will automatically shut off until needed to maintain the temperature selected There may be times when Auto mode is undesirable In that case the refrigeration may be set to On or Off When the refrigeration is set to On or Off the refrigeration is on or off for all temperatures CAUTION The refrigeration may be damaged or the lifetime shortened if used above 60 C for more than one hour The parameter is indicated by CooL rst Cooling mode parameter Press SET to access the parameter setting Auto Cooling mode set for automatic To change to On or Off mode press DOWN until the desired mode appears and then press SET On Cooling mode set to on OFF Cooling mode set to off Individual steps may be skipped by pressing EXIT Hot Gas Bypass Mode The hot gas bypass HGb system is a method of reducing cooling or refrigeration capacity It is normally used above approximately 0 C Reducing cooling capacity helps improve temperature stability in the
75. e may be a defective electronic component contact an Authorized Service Center see Authorized Service Centers in Chapter 1 for assistance The controller controls or attempts to control at an inaccurate temperature The controller operates normally except when controlling at a specified set point At this set point the temperature displayed does not agree with the temperature measured by the user s reference thermometer to within the specified accuracy This problem may be caused by an actual difference in temperature between the points where the control probe and thermometer probe measure temperature by erroneous bath calibration parameters or by a damaged control probe Check that the bath has an adequate amount of fluid in the tank and that the stirrer is operating properly Check that the thermometer probe and control probe are both fully inserted into the bath to minimize temperature gradient errors Check that the calibration parameters are all correct according to the Report of Test If not re program the constants The memory backup battery may be weak causing errors in data as described in the problem The display flashes cutout and an incorrect process temperature Check that the control probe has not been struck bent or damaged If the cause of the problem remains unknown contact an Authorized Troubleshooting 13 13 5 Service Center see Authorized Service Centers in Chapter 1 f
76. een upper and lower case letters hence either may be used Commands may be abbreviated to the minimum number of letters which determines a unique command A command may be used to either set a parameter or display a parameter depending on whether or not a value is sent with the command following a character For example an s lt cr gt returns the current set point and an s 50 00 lt cr gt sets the set point to 50 00 degrees In the list of commands characters or data within brackets and are optional for the command A slash denotes alternate characters or data Numeric data denoted by n may be entered in decimal or exponential notation Characters are shown in lower case although upper case may be used Spaces may be added within command strings and will simply be ignored Backspace BS ASCII 8 may be used to erase the previous character A terminating CR is implied with all commands Cooling Control The 7341 bath has a fully automated refrigeration control system when the cooling power switch on the front panel is activated Under normal conditions the refrigeration is on at any temperature below approximately 60 C see Refrigeration in Chapter 8 When the bath is controlling at temperatures between 0 C and 60 C the refrigeration is in the hot gas bypass or reduced cooling mode Below 0 C the refrigeration is in the high cooling mode and the hot gas bypass is turned off automatically
77. emperature range of the calibration Bath fluids should be selected to operate safely with adequate thermal properties to meet the application requirements For operation at 7341 Users Guide 4 4 moderate bath temperatures clean distilled water works well Carefully pour the fluid into the bath tank through the large rectangular access hole above the tank avoiding spilling any fluid Caution When filling the tank ensure the immersion coils are completely covered DO NOT FILL ABOVE THE STIR BAFFLE See Figure 4 1 MIN FILL Maximum Fill Level Top of Baffle Minimum Fill Level Line haz001 eps Figure 4 1 Stir Baffle Fill Levels Quick Start Power 4 4 5 An overflow drain is provided for excess bath fluid due to expansion This drains the fluid into the fluid expansion reservoir for reuse See Fluid Expansion Reservoir in Chapter 7 for details in using the reservoir Note As the temperature of the bath increases the fluid level will increase see Chapter 6 Power Plug the bath power cord into a mains outlet of the proper voltage frequency and current capability Refer to Specifications in Chapter 3 for power details Refer to and read the CAUTION at the front of the manual concerning brownout and over voltage protection Check the back panel label for the correct voltage and frequency prior to energizing the bath Turn the bath on using the front panel POWER switch The bath will turn on and begin to heat
78. ending upon bath temperature and operation needs as described below The refrigeration system is activated when the switch on the front panel is turned on If the bath is below the 60 C cutoff point and is set to a temperature above 60 C the refrigeration shuts off to protect it from overheating and creating excessive internal pressures If the bath is above 60 C and is set to a new temperature below the cutoff temperature the refrigeration turns on again at 59 C When the bath is controlling at temperatures between the 60 C and 0 C the bath operates in a low cooling capacity mode with the hot gas bypass valve on HGb on The HGb system reduces the cooling capacity and helps to improve the bath stability within that temperature range Since more cooling capacity is generally required below 0 C the hot gas bypass is turned off HGb off providing more cooling capacity When the bath is cooled from temperatures below the cutoff point to 0 C and if the new set point is at least 2 C below the current bath temperature the cooling turns to maximum capacity HGb off until the bath is within about 0 5 C of the new set point This provides the fastest cooling possible to achieve the new set point temperature As indicated the cooling is always maximum below 0 C When heating the bath from temperatures of 40 C and the new set point is at least 10 C above the current bath temperature the refrigeration turns off until the bath is about 1
79. es to the bath through the DB 9 connector on the back of the instrument Figure 10 1 shows the pin out of this connector and the suggested cable wiring To eliminate noise the serial cable should be shielded with low resistance between the connector DB 9 and the shield haz007 eps Figure 10 1 Serial Communications Cable Wiring 7341 Users Guide 10 4 Setup Before operation the serial interface of the bath must first be set up by programming the baud rate and other configuration parameters These parameters are programmed within the serial interface menu To enter the serial parameter programming menu press EXIT while holding down SET then release both buttons to enter the secondary menu Press SET repeatedly until the display reads ProbE This is the menu selection Press UP repeatedly until the serial interface menu is indicated with SErIAL Finally press SET to enter the serial parameter menu In the serial interface parameters menu are the baud rate the sample rate the duplex mode and the linefeed parameter Baud Rate The baud rate is the first parameter in the menu The display prompts with the baud rate parameter by showing BAUd Press SET to choose to set the baud rate The current baud rate value is displayed The baud rate of the bath may be programmed to 300 600 1200 or 2400 baud The baud rate is pre programmed to 2400 baud Use UP or DOWN to change the
80. ese symbols may be used on the instrument or in this manual Table 1 1 International Electrical Symbols Symbol Description AC Alternating Current AC DC Battery Complies with European Union directives DC Double Insulated Electric Shock Fuse PE Ground Hot Surface Burn Hazard Read the User s Manual Important Information O Off I On Canadian Standards Association CAT II OVERVOLTAGE Installation CATEGORY II Pollution Degree 2 per IEC1010 1 refers to the level of Impulse Withstand Voltage protection provided Equipment of OVERVOLTAGE CATEGORY II is energy consuming equipment to be supplied from the fixed installation Examples include household office and laboratory appliances C TIC Australian EMC mark The European Waste Electrical and Electronic Equipment WEEE Directive 2002 96 EC mark 7341 Users Guide 1 4 Safety Information Use this instrument only as specified in this manual Otherwise the protection provided by the instrument may be impaired Refer to the safety information in Warnings and Cautions sections The following definitions apply to the terms Warning and Caution WARNING identifies conditions and actions that may pose hazards to the user CAUTION identifies conditions and actions that may damage the instrument being used Warning To avoid po
81. ety In order to comply with the European Low Voltage Directive 73 23 EEC Fluke equipment has been designed to meet the following standards IEC 1010 1 EN 61010 1 IEC 1010 2 010 EN 61010 2 010
82. fficient time for the probes to settle and the temperature of the bath to stabilize One of the significant dividends of using a bath rather than a dry well to calibrate multiple probes is that the probes do not need to be identical in construction The fluid in the bath allows different types of probes to be calibrated at the same time However stem effect from different types of probes is not totally eliminated Even though all baths have horizontal and vertical gradients these gradients are minimized inside the bath work area Nevertheless probes should be inserted to the same depth in the bath liquid Be sure that all probes are inserted deep enough to prevent stem effect From research at Hart Scientific we suggest a general rule of thumb for immersion depth to reduce the stem effect to a minimum 20 x the diameter of the UUT the sensor length Do not submerge the probe handles If the probe handles get too warm during calibration at high temperatures a heat shield could be used just below the probe handle This heat shield could be as simple as aluminum foil placed around the handle or as complicated as a specially designed reflective metal apparatus When calibrating over a wide temperature range starting at the highest temperature and progressing down to the lowest temperature can generally achieve better results Probes can be held in place in the bath by using probe clamps or drilling holes in the 7341 Users Guide 6 4 access
83. haz004 eps Figure 8 1 Chart of Various Bath Fluids and Their Properties Pour Point This represents a handling limit for the fluid Viscosity Points shown are at 50 and 10 centistokes viscosity When viscosity is greater than 50 centistokes stirring is very poor and the fluid is unsatisfactory for bath applications Optimum stirring generally occurs at 10 centistokes and below Fume Point Indicates the point at which a fume hood or ventilation system must be used to prevent health hazards posed by fume vapors In the graph it is assumed that the bath access hole is covered at this point This is subject to user s company policy Fluke recommends the use of a ventilation system as soon as the fluid produces vapors Keep the access hole covered to reduce evaporation Flash Point The point at which ignition may occur The point shown may be either the open or closed cup flash point Refer to the flash point discussion in Safety in Chapter 8 Boiling Point At or near the boiling point of the fluid the temperature stability is difficult to maintain Fuming or evaporation is excessive Large amounts of heater power may be required to maintain the temperature because of the heat of vaporization 7341 Users Guide 8 10 Decomposition The temperature may reach a point at which decomposition of the fluid begins Further increasing the temperature may accelerate decomposition to the point of danger or impracticality Silicone oils can oxidize c
84. hot There is a stainless steel dust cover over the reservoir with an elbow on top that the drain tube is inserted into The reservoir hangs on a hook and is attached to the bath with a thumbscrew Warning The drain tube and dust cover may be hot Always be sure the drain tube is fully inserted into the elbow of the dust cover To drain fluid from the reservoir first remove the dust cover and set aside Then undo the thumbscrew and carefully lift it with the two handles provided on the back The fluid may then be poured back into the bath when it is cooler or poured into some other approved container Caution Be careful when handling hot fluids burns can result When the excess fluid has been removed reverse the process to replace the reservoir and dust cover Always wipe away spilt fluid if spilling occurs Warning The overflow tube is not large enough to handle large flow rates encountered by overfilling the tank It is intended for expanding fluid rates from heating only Fill only until the level reaches the top of the stir baffle see Figure 4 1 8 1 Chapter 8 General Operation Title Page Heat Transfer Fluid 8 3 Temperature Range 8 3 Viscosity
85. information on Fluid Expansion Reservoir use No matter what fluid is used DO NOT exceed the recommended fluid viscosity DO NOT change the values of the bath calibration constants from the factory set values The correct setting of these parameters is important to the safety and proper operation of the bath The refrigeration may be damaged or the lifetime shortened if the set point temperature is set above 60 C for more than one hour with the refrigeration manually on Ensure that the refrigeration is off when the bath is used above 60 C The Factory Reset Sequence should be performed only by authorized personnel if no other action is successful in correcting a malfunction You must have a copy of the most recent Report of Test to restore the test parameters DO NOT operate this instrument in an excessively wet oily dusty or dirty environment Silicone oils require additional ventilation to prevent an oily dirty environment Before You Start Authorized Service Centers 1 1 7 Most probes have handle temperature limits Be sure that the probe handle temperature limit is not exceeded in the air above the instrument The instrument and any thermometer probes used with it are sensitive instruments that can be easily damaged Always handle these devices with care Do not allow them to be dropped struck stressed or overheated COLD BATHS Refrigerated baths require that the condens
86. ing coil be cleaned periodically Accumulation of dust and dirt on the condenser will result in premature failure of the compressor Bath or compressor lifetime may be affected by o Cycling the heat source through extreme temperature ranges the full temperature limit of the heat source Cycling the instrument can cause excessive stress on the compressors Compressor manufacturers recommend for longest lifetime that the instrument be set at one temperature and left on at that temperature o Turning the instrument on and off frequently adds wear and tear to the compressor Authorized Service Centers Please contact one of the following authorized Service Centers to coordinate service on your Fluke product Fluke Corporation 799 E Utah Valley Drive American Fork UT 84003 9775 USA Phone 1 801 763 1600 Telefax 1 801 763 1010 E mail support hartscientific com Fluke Nederland B V Customer Support Services Science Park Eindhoven 5108 5692 EC Son NETHERLANDS Phone 31 402 675300 Telefax 31 402 675321 E mail ServiceDesk fluke nl 7341 Users Guide 1 8 Fluke Int l Corporation Service Center Instrimpex Room 2301 Sciteck Tower 22 Jianguomenwai Dajie Chao Yang District Beijing 100004 PRC CHINA Phone 86 10 6 512 3436 Telefax 86 10 6 512 3437 E mail xingye han fluke com cn Fluke South East Asia Pte Ltd Fluke ASEAN Regional Office Service Center 60
87. int to n s etpoint n t emperature n s 150 t 150 Instrument Range 40 to 150 C Read vernier v ernier v v 9 99999 v 0 00000 Set vernier to n v ernier n v 00018 Depends on Configuration Read scan function sc an sc scan ON or OFF scan ON Set scan function sc an on of f Turn scan function on sc an on sc on Turn scan function off sc an of f sc of Read scan rate sr ate sr srat 9 999 C or F min srat 0 010 C min Set scan rate to n degrees per minute sr ate n sr 5 0 001 to 5 000 C min 0 001 to 9 000 F min Read temperature t emperature t t 9999 99 C or F t 55 69 C Read temperature units u nits u u x u C Set temperature units u nits c f Set temperature units to Celsius u nits c u c Set temperature units to Fahrenheit u nits f u f Digital Communication Interface Cooling Control10 10 7 Table 10 1 Interface Command Summary cont Command Description Command Format Command Example Returned Returned Example Acceptable Values Ramp and Soak Menu Read number of programmable set points pn pn pn 9 pn 2 Set number of programmable set points to n pn n pn 4 Read programmable set point number n psn ps3 psn 9999 99 C or F ps1 50 00 C Set programmable set point number n to n psn n ps3 50 1 to 8 Instrument Range 40 to 150 C Read program set point soak time pt pt ti 999
88. lay 2 the control buttons 3 the bath on off power switch 4 the control indicator light and 5 the cooling on off switch haz003 eps Figure 7 1 Front Control Panel 1 The digital display is an important part of the temperature controller It displays the set point temperature and bath temperature as well as the various other bath functions settings and constants The display shows temperatures according to the selected scale units C or F 2 The control buttons SET DOWN UP and EXIT are used to set the bath temperature set point access and set other operating parameters and access and set bath calibration parameters A brief description of the functions of the buttons follows SET Used to display the next parameter in a menu and to set parameters to the displayed value DOWN Used to decrement the displayed value of parameters UP Used to increment the displayed value EXIT Used to exit from a menu When EXIT is pressed any changes made to the displayed value will be ignored 3 The on off switch controls power to the entire bath including the stirring motor 4 The control indicator is a two color light emitting diode LED This indicator lets the user visually see the ratio of heating to cooling When the indicator is red the heater is on and when it is green the heater is off and the bath is cooling 5 The cooling switch turns on the refrigeration for control below 50 C and rapi
89. ment memory 4 40 0 New set point memory 4 40 0 C Press SET to accept the new selection and access the set point value S Accept selected set point memory Set point Value After selecting the set point memory and pressing SET the set point value may be adjusted in increments of 0 01 C or F The set point value is displayed with the units C or F at the left C 40 00 Set point 4 value in C If the set point value does not need to be changed press EXIT to resume displaying the bath temperature Press UP or DOWN to adjust the set point value U Increment display C 42 50 New set point value When the desired set point value is reached press SET to accept the new value and 7341 Users Guide 9 6 access the set point vernier If EXIT is pressed any changes made to the set point are ignored S Accept new set point value Set point Vernier The user may want to adjust the set point slightly to achieve a more precise bath temperature The set point vernier allows one to adjust the temperature below or above the set point by a small amount with very high resolution Each of the 8 stored set points has an associated vernier setting The set point vernier can be set in increments of 0 00018 C The vernier is accessed from the set point by pressing SET The vernier setting is displayed as a 6 digit number with five digits after the decimal point This is a temperature offset in
90. n control 7341 Users Guide 2 2 3 1 Chapter 3 Specifications and Environmental Conditions Title Page Specifications 3 3 Environmental Conditions 3 4 7341 Users Guide 3 2 Specifications and Environmental Conditions Specifications 3 3 3 Specifications Table 3 1describes the product specifications Table 3 1 Specifications Item Description Range 45 C to 150 C Stability 2 sigma 0 005 C at 40 C ethanol 0 005 C at 25 C water 0 007 C at 150 C 5012 oil Uniformity 0 007 C at 40 C ethanol 0 007 C at 25 C water 0 010 C at 150 C 5012 oil Heating Time 120 minutes from 25 C to 150 C 5012 oil 115V Cooling Time 130 minutes from 25 C to 45 C ethanol Stabilization Time 15 20 minutes Temperature Setting Digital display with push button entry Set point Resolution 0 01 0 00018 in high resolution Display Temperature Resolution 0 01 Digital Setting Accuracy 1 C Digital Setting Repeatability 0 01 C Heater 700 Watts 115V 230V Nominal Access Opening 6 8 x 4 7 172 x 119 mm Immersion Depth 18 457 mm without liquid in glass thermometer cal kit 19 482 mm with liquid in glass thermometer cal kit Wetted Parts 304
91. nterface it Software and User s Guide Tipping Prevention Bracket including mounting hardware for wood or concrete floor 2019 DCB Kit Liquid in Glass LIG Adapter and Carousel optional 2069 Scope Liquid in Glass LIG with mounts optional If you are missing any item please call an Authorized Service Center To locate an Authorized Service Center near you see Authorized Service Centers in Chapter 1 Set Up Warning The instrument is equipped with a soft cutout user settable firmware and a hard cutout set at the factory Check the flash point boiling point or other fluid characteristic applicable to the circumstances of the instrument operation Ensure that the soft cutout is adjusted to the fluid characteristics of the application As a guideline the soft cutout should be set 10 C to 15 C below the flash point of the bath fluid See Heat Transfer Fluid in Chapter 8 for specific information on bath fluids and Cutout in Chapter 10 Set up of the bath requires careful unpacking and placement of the bath filling the bath with fluid and connecting power Consult Chapter 5 Installation for detailed instructions for proper installation of the bath Be sure to place the bath in a safe clean and level location Refer to Tipping Prevention Bracket in Chapter 5 for Tipping Prevention Bracket installation instructions Fill the bath tank with an appropriate liquid Be sure to select the correct fluid for the t
92. oceeding to the next set point The duration is counted from the time the temperature reaches the set point Pt 15 Soak time in minutes Use the UP or DOWN buttons to change the time Pt 5 New soak time Press SET to continue S Save new setting Program Function Mode The next parameter is the program function or cycle mode There are four possible modes which determine whether the program scans up from set point 1 to n only or both up and down from set point n to 1 and also whether the program stops after one cycle or repeats the cycle indefinitely Table 9 1 shows the action of each of the four program mode settings Controller Operation Secondary Menu 9 9 9 Table 9 1 Program Mode Setting Actions Function Action 1 up stop 2 up down stop 3 up repeat 4 up down repeat Pf 1 Program mode Use the UP or DOWN buttons to change the mode Pf 4 New mode Press SET to continue S Enter program menu Program Control The final parameter in the program menu is the control parameter Three options are available for controlling the ramp and soak program The options are to start the program from the beginning GO continue the program from where it was when it was stopped Cont or stop the program OFF Pr OFF Program presently off Use the UP or DOWN buttons to change the status Pr Cont Start cycle from beginning Press SET to activate the new pr
93. ode cm ode r eset a uto Set cutout to be reset manually cm ode r eset cm r Set cutout to be reset automatically cm ode a uto cm a Serial Interface Menu Read serial sample setting sa mple sa sa 9999 sa 1 Set serial sampling setting to n seconds sa mple n sa 0 0 to 4000 Set serial duplex mode du plex f ull h alf FULL or HALF Set serial duplex mode to full du plex f ull du f Set serial duplex mode to half du plex h alf du h Set serial linefeed mode lf eed on of f Set serial linefeed mode to on lf eed on lf on Set serial linefeed mode to off lf eed of f lf of Calibration Menu Read C0 calibration parameter c0 c0 c0 9 9999 c0 0 0002 Set C0 calibration parameter to n c0 n c0 0 Unlimited Read CG calibration parameter cg cg cg 999 99 cg 406 25 Digital Communication Interface Cooling Control10 10 9 Set CG calibration parameter to n cg n cg 406 25 Unlimited Table 10 1 Interface Command Summary cont Command Description Command Format Command Example Returned Returned Example Acceptable Values Read Cool mode co ol co co xxx co auto Set Cool mode co ol of f on au to On Off Auto Set Cool mode to Off co ol of f co of Set Cool mode to On co ol on co on Set Cool mode to Auto co ol au to co au Read HGb mode hg b hg hgb xxx hgb auto Set HGb mode hg b of f
94. ogram control command and return to the temperature display S Activate new command Secondary Menu Functions which are used less often are accessed within the secondary menu The secondary menu is accessed by pressing SET and EXIT simultaneously and then releasing The first function in the secondary menu is the heater power display Heater Power The temperature controller controls the temperature of the bath by pulsing the heater on and off The total power being applied to the heater is determined by the duty cycle or the ratio of heater on time to the pulse cycle time This value may be estimated by watching the red green control indicator light or read directly from the digital display By knowing the amount of heating the user can tell if the bath is heating up to the set point cooling down or controlling at a constant temperature Monitoring the percent heater power lets the user know the stability of the bath temperature With good control stability the percent heating power should not fluctuate more than 1 within one minute The heater power display is accessed in the secondary menu Press SET and EXIT simultaneously and release The heater power is displayed as a percentage of full power 7341 Users Guide 9 10 S E Access heater power in secondary menu 12 Pct Heater power in percent To exit out of the secondary menu press EXIT To continue on to the proportional band setting function
95. oice Buyer for importation costs of repair replacement parts when product purchased in one country is submitted for repair in another country Fluke s warranty obligation is limited at Fluke s option to refund of the purchase price free of charge repair or replacement of a defective product which is returned to a Fluke authorized service center within the warranty period To obtain warranty service contact your nearest Fluke authorized service center to obtain return authorization information then send the product to that service center with a description of the difficulty postage and insurance prepaid FOB Destination Fluke assumes no risk for damage in transit Following warranty repair the product will be returned to Buyer transportation prepaid FOB Destination If Fluke determines that failure was caused by neglect misuse contamination alteration accident or abnormal condition of operation or handling including overvoltage failures caused by use outside the product s specified rating or normal wear and tear of mechanical components Fluke will provide an estimate of repair costs and obtain authorization before commencing the work Following repair the product will be returned to the Buyer transportation prepaid and the Buyer will be billed for the repair and return transportation charges FOB Shipping Point THIS WARRANTY IS BUYER S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL OTHER WARRANTIES EXPRESS OR IMPLIED INCLUDIN
96. or assistance The controller does not maintain controller parameters or parameters are reset each time the power to the unit is removed Note Before performing the memory check you need to record the controller calibration parameters found in the CAL menu of the instrument and any user adjusted parameters that you have changed such as the programmable set points and proportional band Memory Check Doing a memory check is the easiest way to verify the ability of the battery to maintain controller parameters 1 Power off the instrument 2 Disconnect the instrument from AC power for 10 seconds 3 Reconnect the AC power and power on the instrument 4 If the display shows InIT and or the cycle count shows a low number such as 0002 the battery is spent and should be replaced Contact an Authorized Service Center for assistance 5 After replacing the battery you must reprogram the calibration and user adjustable parameters into the controller The controller shows that the output power is steady but the process temperature is unstable Possible causes are an improper proportional band setting or the fluid being used If the bath temperature does not achieve the expected degree of stability when measured using a thermometer try adjusting the proportional band to a narrower width as discussed in Proportional Band in Chapter 9 Check to ensure the fluid has not deteriorated or is not too thick The
97. or cool to reach the previously programmed temperature set point The front panel LED display will indicate the actual bath temperature Set the cooling switch to ON for below or near ambient temperatures Note The actual temperature where cooling is required depends on the bath fluid and whether a cover is used over the access well Setting the Temperature In the following discussion and throughout this manual a solid box around the word SET UP DOWN or EXIT indicates the panel button to press while the dotted box indicates the display reading on the front panel Explanation of the button function or display reading is written at the right To view or set the bath temperature set point proceed as follows The front panel LED display normally shows the actual bath temperature 24 68 C Bath temperature display When SET is pressed the display shows the set point memory that is currently being used and its value Eight set point memories are available S Access set point selection 1 25 0 Set point 1 25 0 C currently used Press SET to select this memory and access the set point value S Access set point value C25 00 Current value of set point 1 25 00 C Press UP or DOWN to change the set point value U Increment display C30 00 New set point value Press SET to accept the new value and display the vernier value The bath begins heating or cooling to the new set point 7341 Users Guide 4 6
98. preventing hazardous vaporization breakdown or ignition of the liquid The cutout temperature is programmable by the operator from the front panel of the controller It must always be set below the upper temperature limit of the fluid and no more than 10 degrees above the upper temperature limit of the bath If the cutout is activated because of excessive bath temperature power to the heater is shut off and the bath cools The display flashes Cut out and the message will be sent over the communication ports The bath cools until it reaches a few degrees below the cutout set point temperature At this point the action of the cutout is determined by the setting of the cutout mode parameter The cutout has two selectable modes automatic reset or manual reset If the mode is set to automatic the cutout automatically resets itself when the bath temperature falls below the reset temperature allowing the bath to heat up again If the mode is set to manual the heater remains disabled until the user manually resets the cutout The cutout set point may be accessed within the secondary menu Press SET and EXIT to enter the secondary menu and show the heater power Then press SET twice to access the cutout set point S E Access heater power in secondary menu 12 Pct Heater power in percent S Access proportional band Pb 0 101C Proportional band setting S Access cutout set point CO 110C Cutout set point To change
99. s less than one hour above 60 C but less than 100 C This list is not intended to be complete but only suggests some of the situations when automatic modes may not be best Most of the time the automatic functions are adequate and should be used 9 1 Chapter 9 Controller Operation Title Page Bath Temperature 9 3 Reset Cutout 9 3 Temperature Set point 9 5 Programmable Set points 9 5 Set point Value 9 5 Set point Vernier 9 6 Scan 9 6 Scan Control 9 6 Scan Rate 9 6 Temperature Scale Units
100. splay The units C or F of the temperature value are displayed at the right For example 25 00C Bath temperature in degrees Celsius The temperature display function may be accessed from any other function by pressing the EXIT button Reset Cutout Cut out Indicates cutout condition The message continues to flash between the actual temperature and Cut out until the temperature is reduced and the cutout is reset The cutout has two modes automatic reset and manual reset The mode determines how the cutout is reset which allows the bath to heat up again When in automatic mode the cutout will reset itself as soon as the temperature is lowered below the cutout set point With manual reset mode the cutout must be reset by the operator after the temperature falls below the set point When the cutout is active and the cutout mode is set to manual reset then the display will flash cutout until the user resets the cutout To access the reset cutout function press the SET button S Access cutout reset function The display indicates the reset function 7341 Users Guide 9 4 haz005 eps Figure 9 1 Controller Operation Flowchart rEsEt Cutout reset function Press SET once more to reset the cutout S Reset cutout Controller Operation Temperature Set point 9 9 5 This action switches the display to the set temperature function To return to displaying the temperature display press the
101. ssible electrical shock or personal injury follow these guidelines GENERAL DO NOT use the instrument for any application other than calibration work The instrument was designed for temperature calibration Any other use of the instrument may cause unknown hazards to the user DO NOT use the instrument in environments other than those listed in the user s guide DO NOT overfill the bath Overflowing extremely cold or hot fluid may be harmful to the operator See Bath Preparation and Filling in Chapter 5 for specific instructions Follow all safety guidelines listed in the user s manual Calibration Equipment should only be used by Trained Personnel If this equipment is used in a manner not specified by the manufacturer the protection provided by the equipment may be impaired Before initial use or after transport or after storage in humid or semi humid environments or anytime the instrument has not been energized for more than 10 days the instrument needs to be energized for a dry out period of 2 hours before it can be assumed to meet all of the safety requirements of the IEC 1010 1 If the product is wet or has been in a wet environment take necessary measures to remove moisture prior to applying power such as storage in a low humidity temperature chamber operating at 50 C for 4 hours or more DO NOT operate high temperature baths 500 C near flammable materials Extreme
102. t Sequence Factory Reset Sequence Hold the SET and EXIT buttons down at the same time while powering up the instrument The instrument display shows init the model number and the firmware version Each of the controller parameters and calibration constants must be reprogrammed The values can be found on the Report of Test that was shipped with the instrument The displayed process temperature is in error and the controller remains in the cooling or the heating state at any set point value Possible causes may be either a faulty control probe or erroneous data in memory The probe may be disconnected burned out or shorted The probe is located inside the stirrer motor cover Check that the probe is connected properly The probe may be checked with an ohmmeter to see if it is open or shorted The probe is a platinum 4 wire Din 43760 type The resistance should read 0 2 to 2 0 ohms between pins 1 and 2 on the probe connector and 0 2 to 2 0 ohms between pins 3 and 4 It should read 100 to 300 ohms between pins 1 and 4 depending on the temperature If the probe appears to be defective contact an Authorized Service Center see Authorized Service Centers in Chapter 1 for assistance If the problem is not the probe erroneous data in memory may be the cause Re initialize the memory as discussed in the problem The display flashes cutout and an incorrect process temperature If the problem remains the caus
103. terface Title Page Serial Communications 10 3 Wiring 10 3 Setup 10 4 Baud Rate 10 4 Sample Period 10 4 Duplex Mode 10 4 Linefeed 10 4 Serial Operation 10 4 IEEE 488 Communication optional 10 4 Setup 10 5 IEEE 488 Address 10 5 Transmission Termination 10 5 IEEE 488 Operation
104. the cutout set point press UP or DOWN D Decrement display CO 75C New cutout set point To accept the new cutout set point press SET S Access cutout set point The next function is the configuration menu Press EXIT to resume displaying the bath temperature Controller Operation Controller Configuration 9 9 13 Controller Configuration The controller has a number of configuration and operating options and calibration parameters which are programmable via the front panel These are accessed from the secondary menu after the cutout set point function by pressing SET There are 5 sets of configuration parameters probe parameters operating parameters serial interface parameters IEEE 488 interface parameters and controller calibration parameters The menus are selected using the UP and DOWN keys and then pressing SET Pressing EXIT in any secondary menu exits and returns to displaying the temperature see Figure 9 1 Probe Parameters The probe menu is indicated by PrObe Probe parameters menu Press SET to enter the menu The probe parameters menu contains the parameters R0 and ALPHA which characterize the resistance temperature relationship of the platinum control probe These parameters may be adjusted to improve the accuracy of the bath This procedure is explained in detail in Chapter 11 Calibration Procedure The probe parameters are accessed by pressing
105. thermal conductivity heater power setting operating temperature and stirring Thus the proportional band width may require adjustment for best bath stability when any of these conditions change Of these the most significant factors affecting the optimum proportional band width are heater power setting and fluid viscosity The proportional band should be wider when the higher power setting is used so that the change in output power per change in temperature remains the same The proportional band should also be wider when the fluid viscosity is higher Controller Operation Proportional Band 9 9 11 because of the increased response time The proportional band width is easily adjusted from the bath front panel The width may be set to discrete values in degrees C or F depending on the selected units The optimum proportional band width setting may be determined by monitoring the stability with a high resolution thermometer or with the controller percent output power display Narrow the proportional band width to the point at which the bath temperature begins to oscillate and then increase the band width from this point to 3 or 4 times wider Table 9 2 lists typical proportional band settings for optimum performance with a variety of fluids at selected temperatures Table 9 2 Typical Proportional Band Settings for Various Fluids Fluid Temperature Proportional Band Stability Water 30 C 0 31 C 0 003 C Water 60 C 0 31 C 0
106. til the IEEE 488 interface menu is indicated with IEEE Press SET to enter the IEEE 488 parameter menu IEEE 488 Address The IEEE 488 address is indicated with AddreSS Press SET to program the address The default address is 22 Change the device address of the bath if necessary to match the address used by the communication equipment by pressing UP or DOWN Press SET to save the new setting or EXIT to abort and skip to the next parameter Transmission Termination The IEEE 488 transmission termination is indicated with EOS Press SET to access the termination character The present setting is displayed Press UP or DOWN to change the setting Press SET to save the new setting or EXIT to abort and skip to the next parameter IEEE 488 Operation Commands may now be sent via the IEEE 488 interface to read or set the temperature or access other controller functions All commands are ASCII character strings and are terminated with a carriage return CR ASCII 13 Interface commands are listed below Interface Commands The various commands for accessing the bath controller functions via the digital interfaces are listed in this section see Table 10 1 These commands are used with both the RS 232 serial interface and the IEEE 488 GPIB interface In either case the commands are terminated with a carriage return character The interface makes no distinction betw
107. to set the bath temperature with high resolution set the cutout temperature adjust the proportional band monitor the heater output power and program the controller configuration and calibration parameters The controller may be operated in temperature units of degrees Celsius or Fahrenheit The controller is operated and programmed from the front control panel using the four key switches and digital General Operation Refrigeration 8 8 11 LED display Remote digital operation with the controller is possible via the standard RS 232 serial port The controller may be optionally equipped with an IEEE 488 GPIB digital interface Operation of the controller using the front control panel is discussed following in Chapter 9 Controller Operation Operation using the digital interface is discussed in Chapter 10 Digital Communication Interface When the controller is set to a new set point the bath heats or cools to the new temperature Once the new temperature is reached the bath usually takes 15 20 minutes for the temperature to settle and stabilize There may be a small overshoot or undershoot of about 0 5 C during this process Refrigeration Cooling is provided by a compact refrigeration system utilizing the ozone safe R 507 HFC refrigerant Refrigeration is often not needed when the bath is above 45 to 60 C The automated system automatically turns the system off when above 60 C The refrigeration system automatically changes modes dep
108. uplex any commands received by the bath via the serial interface are executed and immediately echoed or transmitted back to the device of origin With half duplex the commands are executed but not echoed The duplex mode parameter is indicated by dUPL Serial duplex mode parameter Press SET to access the mode setting dUP FULL Current duplex mode setting The mode may be changed using UP or DOWN and pressing SET dUP HALF New duplex mode setting Linefeed The final parameter in the serial interface menu is the linefeed mode This parameter enables on or disables off transmission of a linefeed character LF ASCII 10 after transmission of any carriage return The linefeed parameter is indicated by LF Serial linefeed parameter Press SET to access the linefeed parameter LF On Current linefeed setting The mode may be changed using UP or DOWN and pressing SET LF OFF New linefeed setting IEEE 488 Parameters Baths may optionally be fitted with an IEEE 488 GPIB interface In this case the user may set the interface address and the transmission termination character within the IEEE 488 parameter menu This menu does not appear on baths not fitted with the interface The menu is accessed by pressing UP from the serial parameter menu The menu is indicated by IEEE IEEE 488 parameters menu Press SET to enter the menu IEEE 488 Address The IEEE 488 interface must b
109. uture The new values R0 and ALPHA are computed by entering the old values for R0 and ALPHA the calibration temperature set points tL and tH and the temperature errors errL and errH into the following equations If R0 and ALPHA were previously set for 100 000 and 0 0038500 respectively and the data for tL tH errL and errH were as given above then the new values R0 and ALPHA would be computed as 110 116 and 0 0038302 respectively Program the new values R0 and ALPHA into the controller Check the calibration by setting the temperature to tL and 7341 Users Guide 11 4 tH and measuring the errors again If desired the calibration procedure may be repeated again to further improve the accuracy Calibration Example The bath is to be used between 25 C and 75 C and it is desired to calibrate the bath as accurately as possible for operation within this range The current values for R0 and ALPHA are 100 000 and 0 0038500 respectively The calibration points are chosen to be 30 00 and 80 00 C The measured bath temperatures are 29 843 and 79 914 C respectively Refer to Figure 11 1 for applying equations to the example data and computing the new probe constants R0 100 000 ALPHA 0 0038500 tL 30 00 C measured t 29 843 C tH 80 00 C measured t 79 914 C Compute errors errL 29 843 30 00 C 0 157 C errH 79 914 80 00 C 0 086 C Compute R0 R0 0 086 30 0 0157 80 0 80 0
110. y also overheat or damage the stirring motor Viscosity may vary greatly with temperature especially with oils Viscosity increases as temperature decreases When fluid viscosity increases stability performance of the unit may decrease Ensure that stirring occurs at all temperatures When using fluids with higher viscosities the controller proportional band see Proportional Band in Chapter 9 may need to be increased to compensate for the reduced response time Otherwise the temperature may begin to oscillate Specific Heat Specific heat is the measure of the heat storage ability of the fluid Specific heat to a small degree affects the control stability and the heating and cooling rates Generally a lower specific heat means quicker heating and cooling The proportional band may require some adjustment depending on the specific heat of the fluid Thermal Conductivity Thermal conductivity measures how easily heat flows through the fluid Thermal conductivity of the fluid affects the control stability temperature uniformity and temperature settling time Fluids with higher conductivity distribute heat more quickly and evenly improving bath performance Thermal Expansion Thermal expansion describes how much the volume of the fluid changes with temperature Thermal expansion of the fluid must be considered since the increase in 7341 Users Guide 8 4 fluid volume as the bath temperature increases may cause overflow It may be

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