5 - CalPower
Contents
1. 27 8 Troubleshooting 29 8 1 Troubleshooting 29 ii 1 Before You Start 1 1 Symbols Used Table 1 lists the International Electrical Symbols Some or all of these symbols may be used on the instrument or in this manual Hart Scientific Manual Rev 152301 1 1 Before You Start Symbol Description AC AC DC Battery CE DC Double Insulated Electric Shock Fuse PE Ground Hot Surface Read the User s Manual Off On Table 1 International Electrical Symbols 1 2 Safety Information Use this instrument only as specified in this manual Otherwise the pro tection provided by the instrument may be impaired Refer to the safety information in Warnings and Cautions 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 in strument being used Warnings To avoid possible electric shock or personal injury follow these guidelines DO NOT use this instrument to measure the temperature of any hazard ous live component DO NOT use this instrument for any application other than calibration work DO NOT use this instrument in environments other than those listed in the user s guide Use o2. 9 3 3 Electrical Circuit 10 3 4 Warranty 10 4 Installation 13 4 1 Environmental Issues 13 4 2 Mounting 13 4 3 Lead Wire Identification 17 5 Care and Handling Guidelines 19 5 1 SPRT Care 19 5 2 SPRT Handling Guidelines 19 5 3 Metal Ion Contamination of SPRTs 20 5 4 Devitrification of Quartz Glass Fused Silica 21 6 Operation 23 6 1 General 23 6 2 Comparison Calibration of Other Instruments 23 6 3 Measuring Current 23 i 6 4 Immersion Requirements 24 6 5 Thermal EMF 24 6 6 Cooling Rates at High Temperatures 25 7 Accessories 27 7 1 Case 27 7 2 SPRT Termination
3. K Mg and Ca The alkalis found in normal tap water can cause the process to start There is conflicting opinion among the experts as to whether the process can be stopped Some say that once the process starts it does not stop Others indicate that once the alkali is removed the process will stop Removal of the devitrification is not practical as it requires drastic mea sures and is potentially dangerous to the instrument and or the user Devitrification starts with a dulling or opacity of the quartz It develops into a rough and crumbling surface Devitrification ultimately weakens the glass quartz until it breaks or is otherwise no longer useful The best cure for contamination and devitrification is prevention Being aware of the causes and signs of contamination can help the user take the steps necessary to control contamination of the SPRT Keep your SPRT clean and avoid contact with metals at temperatures above 600 C Hart Scientific Manual Rev 152301 21 5 Care and Handling Guidelines 6 Operation 6 1 General For best results be familiar with the operation of the calibration bath or furnace and the read out instrument Be sure to follow the manufacturer s instructions for the read out instrument and the calibration bath or fur nace 6 2 Comparison Calibration of Other Instruments The uniformity and stability of the bath and the degree of accuracy re quired determine the number of temperature measurements nec
4. Manual Rev 152301 7 2 Introduction SPRT Calibration by ITS 90 Fixed Point All calibrations in this section include the following 1 calibration at two levels of current and extrapolation to zero power 2 ITS 90 deviation function coefficients and interpolation tables for the nominal current calibration and the zero power calibration and 3 analysis for compliance to ITS 90 criteria for a standard interpolating instrument of the ITS 90 Order No Temperature ITS 90 Subranges Fixed Points Used 1910 4 200 C to 0 C 4 comp at NBPLN2 TPHg TPW 1910 4 11 200 C to 30 C 4 11 comp at NBPLN2 TPHg TPW MPGa 1910 4 10 200 C to 157 C 4 10 comp at NBPLN2 TPHg TPW FPIn 1910 4 9 200 C to 232 C 4 9 comp at NBPLN2 TPHg TPW FPIn FPSn 1910 4 8 200 C to 420 C 4 8 comp at NBPLN2 TPHg TPW FPSn FPZn 1910 4 7 200 C to 660 C 4 7 comp at NBPLN2 TPHg TPW FPSn FPZn FPAl 1910 5 10 40 C to 157 C 5 10 TPHg TPW MPGa FPIn 1910 5 9 40 C to 232 C 5 9 TPHg TPW MPGa FPIn FPSn 1910 5 8 40 C to 420 C 5 8 TPHg TPW MPGa FPSn FPZn 1910 5 7 40 C to 660 C 5 7 TPHg TPW MPGa FPSn FPZn FPAl 1910 11 0 C to 30 C 11 TPW MPGa 1910 10 0 C to 157 C 10 TPW FPIn 1910 9 0 C to 232 C 9 TPW FPIn FPSn 1910 8 0 C to 420 C 8 TPW FPSn FPZn 1910 7 0 C to 660 C 7 TPW FPSn FPZn FPAl 1910 6 0 C to 962 C 6 TP
5. NVLAP Level I Accuracy Class 2 3 Calibration In order for any instrument to be used as a standard it must be cali brated The SPRTs may be purchased calibrated or non calibrated Hart Scientific s National Voluntary Laboratory Accreditation Program NVLAP has the capability of performing fixed point of comparison cali brations traceable to NIST The 5681 can be economically calibrated us ing the comparison method or any one of several fixed point calibrations matching ITS 90 subranges Fixed point calibration is recommended for the 5683 5684 and 5685 2 3 1 Calibration Options In order for the thermometers to make accurate temperature measure ments they must be calibrated Calibration can be attained through any recognized primary standard laboratory designed to perform temperature calibrations Hart Scientific can provide either comparison calibration or fixed point calibrations as shown in Table 2 2 4 Recalibration The recalibration of the SPRTs should be scheduled according to the user s company Quality Assurance requirements Normally an SPRT is recalibrated annually Unless the SPRT is used only over a limited range calibration over the full range of the SPRT 189 C to 661 C for the 5681 189 C to 480 C for the 5683 and 0 C to 962 C for the 5684 and 5685 is recommended For information on recalibrating your SPRT con 6 Manual Rev 152301 5681 5683 5684 5685 2 Introduction Hart Scientific
6. If the thermometer is an nealed in a furnace above 660 C the furnace should be base metal free 6 DO use the protective case provided or other protection when the ther mometer is not in use 7 DON T subject the thermometer to any physical shock or vibration 8 DON T subject the thermometer to temperatures above the highest specified operating temperature 9 DON T expose the thermometer s handle or cables to extreme temper atures 10 DON T submerge the handle or cable in liquids 5 3 Metal Ion Contamination of SPRTs Since the acceptance of ITS 90 information has been accumulating about contamination of SPRTs ITS 90 extended the range of the SPRT as an interpolation device and new problems manifested themselves Metal ion contamination is one of the new problems and can start at ap proximately 700 C At high temperatures the lattice structure of most metals becomes quite loose This allows some of the metal ions to come off the surface analo gous to steam rising from hot water Since the molecular activity in creases with temperature so does the amount of ion loss and the risk of contamination Ion transfer occurs at different temperatures for different metals Copper nickel iron and manganese are metals that have been attributed to causing contamination In addition the quartz lattice struc ture also becomes quite loose at these high temperatures This allows the quartz to become transparent to these meta
7. Red and black wires have red heat shrink tubing Blue and white wires have black heat shrink tubing See Figure 6 for details Hart Scientific Manual Rev 152301 17 4 Installation BLACK RED Rx White Red Blue Black Figure 6 SPRT Circuit Schematic 5 Care and Handling Guidelines Caution Read before removing the SPRT from the case 5 1 SPRT Care The 5680 series Standard Platinum Resistance Thermometers SPRTs are extremely delicate instruments Great care must be taken in handling the SPRTs to maintain calibration accuracy Vibration or shock may cause the resistance to increase A slight tap to the SPRT tip as it is re moved from an instrument can cause a change in Rtp as high as 1 mK At high temperatures the SPRT may become contaminated if inserted into metal blocks This contamination can effect the accuracy of the sensor if the contamination invades the sensor changing the purity of the platinum wire The fused silica sheath is very fragile and susceptible to contamina tion Once a SPRT is contaminated it can contaminate other standards equipment Copper contamination shows as red smudged on the sheath Any contamination can cause devitrification of the sheath at high temperatures The fused silica sheath should not be handled with bare hands Cotton gloves or other suitable methods should be used in han dling the SPRT The sheath should always be wiped down with 200 proof Ethyl Alcohol or other suitable sol
8. SPRT If the Rtp does not stabilize contact Hart Sci entific Customer Service Severe mechanical shock can permanently damage the SPRT If annealing the SPRT does not resolve the data change contact Hart Scientific Customer Service Oxidation of the platinum sensor may occur after prolonged use between 200 450 C Rtp will show an increase To reduce the effects of oxidation anneal the SPRT at the appropriate tem perature as described above Measure the Rtp again Repeat the annealing Rtp measurement cycle several times This annealing process should return Rtp to within calibration tolerances If the Rtp is within calibration tolerance the SPRT is usable If the Rtp is not within calibration tolerance but it is stable recalibrate the SPRT Data unstable Connection may not be made If the data is unstable at the Triple Point of Water TPW check the connection first If this action does not fix the problem contact Hart Scientific Customer Service The SPRT may be damaged and need re pair Electrical noise in the system If the data is unstable at high temperatures it may be due to electrical noise in the system Re duce the temperature and observe the data If it is stable electrical noise is interfering with the measurements at high temperatures Check the grounding of the readout device and the heat source A faulty ground on either device could interfere with high tempera ture measurements A ground lead wire the fifth wi
9. before construc tion of the SPRT Likewise connection to extension lead wires and readout instruments can be a source of thermal EMF The thermal EMF is caused by a differ ence in temperature between two connections If the two connections are the same temperature there will be little or no thermal EMF effects How ever if there is a substantial temperature difference between connec tions the thermal EMF effects will be significant Therefore cover or insulate any exposed bridge or galvanometer terminals to lessen the 24 Manual Rev 152301 5681 5683 5684 5685 6 Operation source of error The effects of thermal EMF can be canceled by using an AC bridge or a DC bridge with reversible current 6 6 Cooling Rates at High Temperatures The equilibrium concentration of point defects in the pure platinum wire increase exponentially to the increase in temperature If a high cooling rate i e removing a SPRT from a high temperature and cooling it to room temperature in less than a minute occurs above 500 C some of the point defects in the platinum wire become trapped in the crystalline structure causing a slight increase in resistance This slight increase in resistance can be reversed by annealing the SPRT To avoid this prob lem slowly cool the SPRT at a rate of roughly 150 C hour above 500 C before removing to room temperature The SPRT can be safely removed from an instrument at 500 C or less and cooled to room temperat
10. 0 5mK after 100 hours at 450 C The Models 5684 and 5685 cover high temperature ranges up to 1070 C and can be calibrated at the Freezing Point of Silver 961 78 C All four SPRTs are hand constructed at Hart by experts with years of SPRT manufacturing experience Each SPRT is carefully annealed at the appropriate temperatures and precisely tested for stability Convection prevention discs are used to reduce stem errors caused by thermal radia tion For Models 5681 5683 and 5685 the sensing elements are fabri Hart Scientific Manual Rev 152301 5 2 Introduction Figure 1 Model 5681 Standard Platinum Resistance Thermometer cated using high purity platinum wire wound in a strain free design on a fused silica cross frame For Model 5684 the sensing element is formed from high purity platinum wire wound bifilarly around a fused silica sup port The fused silica sheaths are pressure sealed with a special ar gon oxygen mixed gas and fit with a terminal box handle with a strain relieved connection to the four wire cable Gold plated spade lugs termi nate the wires 2 2 Application Hart 5680 series thermometers are classified as primary standards A primary standard is defined in terms of transfer of the ITS 90 from a stan dards laboratory to a customer s laboratory Primary standards are cali brated in a standards lab using known intrinsic values The SPRTs are designed to meet the National Voluntary Laboratory Accreditation s
11. 5681 5683 5684 5685 StandardPlatinum ResistanceThermometer User sGuide Rev 152301 Rev 152301 Copyright 1995 2001 All rights reserved Hart Scientific Inc 799 E Utah Valley Drive American Fork Utah 84003 9775 Telephone 801 763 1600 Fax 801 763 1010 Internet http www hartscientific com E Mail support hartscientific com Table of Contents 1 Before You Start 1 1 1 Symbols Used 1 1 2 Safety Information 2 1 3 Verifying Probe Accuracy 2 1 4 Customer Service Information 3 2 Introduction 5 2 1 General 5 2 2 Application 6 2 3 Calibration 6 2 3 1 Calibration Options 6 2 4 Recalibration 6 2 5 Return Procedure 8 3 Specifications 9 3 1 Specifications 9 3 2 Construction
12. Sensitivity 0 1 C 0 001 C 0 01 C Drift Rate lt 0 002 C 100 hours at 661 C typically lt 0 001 C lt 0 001 C 100 hours at 480 C 0 0005 C typical lt 0 003 C 100 hours at 1070 C typically lt 0 001 C Sensor Support Quartz glass cross Quartz glass strip with notches Quartz glass cross Diameter of Sensor Pt Wire 0 003 0 07 mm 0 016 0 4 mm 0 008 0 2 mm Protective Sheath Quartz glass Diameter 0 28 7 mm Length 20 5 520 mm Quartz glass Diameter 0 28 7 mm Length 26 8 680 mm The official maximum temperature of an SPRT as a defining interpolation instrument of the ITS 90 is 961 78 C but these types of SPRTs were found to be stable up to at least 1070 C The annealing temperature during the stability test was 1085 C The lower temperature limit of these types of SPRTs can be as low as 200 C In general it is suggested that a 25 ohm SPRT be used below 0 C 3 2 Construction Construction of the 5681 5683 5684 and 5685 SPRT is shown in Fig ure 2 and explained below Model 5681 covers the range from 189 C to 661 C The 25 5 sensor element is crafted using high purity platinum wire wound in a strain free design on a fused silica cross frame The 5681 has a sensitivity of 0 1 C Model 5683 covers the range from 189 C to 480 C The 25 5 sensor element is crafted using high purity platinum wire wound in a strain free design on a fus
13. W FPSn FPZn FPAl FPAg SPRT Calibration by Comparison All calibrations in this section include the following 1 ITS 90 deviation function coefficients for the nominal current cali bration 2 bound interpolation table in 1 degree increments in terms of resistance vs T90 for the nominal current calibra tion and 3 analysis for compliance to ITS 90 criteria for a standard interpolating instrument of the ITS 90 Order No Temperature Comparison Points Used 1920 4 9 200 C to 232 C 197 0 C 38 8 C 0 01 C 156 6 C 231 9 C 1920 4 8 200 C to 420 C 197 0 C 38 8 C 0 01 C 231 9 C 419 5 C 1920 4 7 200 C to 660 C 197 0 C 38 8 C 0 01 C 231 9 C 419 5 C 660 3 C 1920 D 9 100 C to 232 C 100 C 38 8 C 0 01 C 156 6 C 231 9 C 1920 D 8 100 C to 420 C 100 C 38 8 C 0 01 C 231 9 C 419 5 C 1920 D 7 100 C to 660 C 100 C 38 8 C 0 01 C 231 9 C 419 5 C 660 3 C 1920 5 9 40 C to 232 C 38 8 C 0 01 C 156 6 C 231 9 C 1920 5 8 40 C to 420 C 38 8 C 0 01 C 231 9 C 419 5 C 1920 10 0 C to 157 C 0 01 C 156 6 C 1920 9 0 C to 232 C 0 01 C 156 6 C 231 9 C 1920 8 0 C to 420 C 0 01 C 231 9 C 419 5 C 1920 7 0 C to 660 C 0 01 C 231 9 C 419 5 C 660 3 C Table 2 Fixed Point and Comparison Calibrations tact Hart Scientific s Customer Service department for an RMA number and current pri
14. cess Hole SPRT Thermometer Guide Tube Water Vapor Borosilicate Glass Reentrant Thermometer Well Water from Ice Bath or Alcohol Water Solid Ice Water Liquid Metal Bushing Soft Pad Ice Bath or Maintenance Bath Cushion Figure 4 Water Triple Point Cell in an Ice Bath Dewar 16 Manual Rev 152301 5681 5683 5684 5685 4 Installation Top Zone Controller Top Zone Heater SPRT Equilibration Block Bottom Zone Controller Bottom Zone Heater Main Controller Main Heater TOP END ZONE PRIMARY ZONE BOTTOM END ZONE Freeze Point Cell Cell Support Container Thermal Block 3 zone subdivision Supercooling Gas Supply Argon Water Cooling Coils PRT Sensor SPRT Thermal Guard Assembly Differential TCs Differential TCs SET SET UP UP DOWN DOWN EXIT EXIT 419 03 C 419 03 C SET DOWN UP EXIT 419 03 C Figure 5 Hart 9114 Metrology Furnace with SPRT in Fixed Point Cell 4 3 Lead Wire Identification All Hart 5680 Series SPRTs are equipped with a four wire cable The same circuit schematic applies to all three SPRTs See Figure 7 Four lead wires are used to cancel lead wire resistance For best results the readout device should be equipped to handle four terminal resistors The lead wire colors are red black white and blue Lead wire pairs at tached to each end of the sensor are identified by heat shrink tubing
15. cing see Section 1 Before You Start 2 5 Return Procedure Note Call Hart Scientific s Customer Service or visit our support page on the world wide web for an RMA number before shipping Extreme care must be taken in shipping an SPRT Place the thermometer in the factory provided protective storage case Be sure the case is latched securely Place the protective case in the original manufacturer s wooden shipping crate or wooden crate with similar dimensions 44 in x 11 3 4 in x 11 3 4 in Place soft insulation on all sides of the crate to cushion the SPRT against mechanical shocks The cover of the crate should be attached with screws We recommend that you label the crate as extremely fragile Whether the thermometer is returned for repair or warranty please include a letter containing the following information Description of the faulty operation and circumstances of failure Complete shipping instructions for the return of the thermometer to the customer 8 Manual Rev 152301 5681 5683 5684 5685 2 Introduction 3 Specifications 3 1 Specifications 5681 5683 5684 5685 Measuring Temperature Range 200 C to 661 C 200 C to 480 C 0 C to 1070 C 0 C to 1070 C Nominal RTPW 25 5 0 25 2 5 Specified Current 1 mA 14 14 mA 5 mA Resistance Ratio W 302 9146 K 1 11807 and W 234 3156 K 0 844235 W 302 9146 K 1 11807 and W 1234 93 K 4 2844
16. e of calibration accompanying your probe However because probes are subject to change from mishandling vibra tion and other forms of mechanical shock Hart does not warrant the be havior of your probe once it has left Hart s control See Section 1 3 Verifying Probe Accuracy for procedures for initially checking your probe 10 Manual Rev 152301 5681 5683 5684 5685 3 Specifications Terminal Gold Plated Terminal Box Protecting Tube Quartz Glass 28 7 mm 85 2159 mm Strain Relief Lead Wire Model 5681 amp 5683 20 5 520 mm Models 5684 amp 85 26 4 670 mm 6 152 mm 3 5 89 mm Figure 2 Standard Dimensions upon receipt at your facility This warranty extends only to the original purchaser and shall not apply to any product which in Hart s sole opin ion has been subject to misuse alteration abuse or abnormal conditions of operation or handling Software is warranted to operate in accordance with its programmed in structions on appropriate Hart products It is not warranted to be error free Hart s obligation under this warranty is limited to repair or replacement of a product which is returned to Hart within the warranty period and is de termined upon examination by Hart to be defective If Hart determines that the defect or malfunction has been caused by misuse alteration abuse or abnormal conditions or operation or handling Hart will repair the product and bil
17. ed silica cross frame The Model 5683 has a sensitivity of 0 1 C The Model 5683 is different from the Model 5681 in the filling gas and manufacture procedure The drift rate of the Model 5683 can be decreased to about half of that of the Model 5861 Hart Scientific Manual Rev 152301 9 3 Specifications Model 5684 covers the range from 0 C to 1070 C The 0 25 High Tem perature Platinum Resistance Thermometer HTPRT sensor uses a high purity platinum wire with a strip shaped support made from high purity fused silica The 5684 demonstrates a typical sensitivity of 0 001 C Model 5685 covers the range from 0 C to 1070 C The 2 5 High Tem perature Platinum Resistance Thermometer HTPRT sensor is con structed of high purity platinum wire bifilarly wound around a fused silica cross frame The 5685 has a sensitivity of 0 01 C 3 3 Electrical Circuit All four SPRTs are provided with a terminal box handle The eight foot cable has four Teflon_coated wires enclosed in a silicon rubber jacket with a stainless steel spring strain relief Gold plated spade lugs termi nate the wires 3 4 Warranty Hart Scientific Inc Hart warrants this product to be free from defects in material and workmanship under normal use and service for a period as stated in our current product catalog from the date of shipment If your probe thermometer was calibrated by Hart Hart also warrants the validity of the data on the certificat
18. essary However to follow good practice procedures always measure the triple point of water Rtp after each temperature measurement This provides the most accurate measurement of the ratio W R R t t tp 6 3 Measuring Current Each SPRT has a specified drive current depending upon the particular sensor The recommended currents are listed in the specifications for each thermometer and in the following table Suggested Drive Currents Model Resistance Drive Current 5681 5683 25 1 mA 5684 0 25 10 mA 5685 2 5 3 mA Errors caused by self heating of the element need to be minimized Al lowing sufficient time for the SPRT to stabilize and the heat to be dis persed into the surrounding medium will provide the most accurate results The Hart testing or calibration certificates provided with the SPRT repre sent data that has been extrapolated For example on Model 5681 mea surements are made at 1 mA and 1 4 mA These measurements are then extrapolated to zero current This can be done graphically by plotting i vs R and extrapolating to zero power or by using the following equation R R i R R i i 0 1 1 2 2 1 2 2 1 2 Hart Scientific Manual Rev 152301 23 6 Operation where R0 Zero current resistance R1 Resistance measured at current i1 R2 Resistance measured at current i2 6 4 Immersion Requirements Stem effect can cause measu
19. f this instrument at high temperatures for extended periods of time can cause the handle to become hot Follow all safety guidelines listed in the user s guide Calibration Equipment should only be used by Trained Personnel Cautions To avoid possible damage to the instrument follow these guidelines DO NOT remove the label from the handle The delicate nature of the instrument is described on the label Read Section 5 entitled Care and Handling Guidelines before remov ing the SPRT from the shipping box or case Incorrect handling can damage the SPRT and void the warranty DO NOT subject the SPRT to mechanical shock Keep the shipping container in case it is necessary to ship the SPRT In correct packaging of the SPRT for shipment can cause irreparable damage 1 3 Verifying Probe Accuracy Before using your probe verify that its behavior has not changed signifi cantly from the most recent calibration as can sometimes occur from mechanical shock during shipping for example To verify your probe check the probe at the triple point of water 0 01 C or in a well con structed ice bath by following these steps 2 Manual Rev 152301 5681 5683 5684 5685 1 Before You Start 1 Connect the probe to a calibrated readout and verify that the probe s coefficients have been correctly entered into the readout 2 Properly prepare a triple point of water cell TPW or ice bath Contact Hart Customer Service if u
20. l ions permitting the transfer of these ions to the pure platinum wire of the SPRT sensor The new alloy formed has a different alpha curve than the pure platinum meaning a loss of calibration Contamination can be spread by an infected SPRT to other primary standards analogous to a virus Therefore it is very important to avoid contamination as much as possible to ensure the longevity of the SPRT itself and to decrease the spread to other standards Isolation of sensitive materials can prevent contamination Pure platinum foil is being used by some experts to absorb the ions before they reach 20 Manual Rev 152301 5681 5683 5684 5685 5 Care and Handling Guidelines the SPRT sensor Silicon carbide is also used by some experts to shield the SPRT sensor because it is less expensive Information on contamina tion effects and prevention is still being gathered by experts in the field 5 4 Devitrification of Quartz Glass Fused Silica Devitrification is a natural process with quartz materials The quartz is uti lized in a glass fused silica state The most stable state for quartz is crystalline Therefore devitrification is the tendency of the quartz to re turn to its most stable state If the quartz is kept extremely clean and free of contamination devitrification will occur only at high temperatures The process occurs more rapidly and at lower temperatures when the glass has become contaminated by alkaline metals Na
21. l the purchaser for the reasonable cost of repair To exercise this warranty the purchaser must forward the product after calling or writing Hart for authorization Hart assumes NO risk for in tran sit damage For service or assistance please contact the manufacturer Hart Scientific Inc 799 East Utah Valley Drive American Fork UT 84003 9775 Phone 801 763 1600 Fax 801 763 1010 E mail support hartscientific com THE FOREGOING WARRANTY IS PURCHASER S SOLE AND EXCLU SIVE REMEDY AND IS IN LIEU OF ALL OTHER WARRANTIES EX PRESS OR IMPLIED INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OR MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR USE HART SHALL NOT BE LIABLE FOR ANY SPECIAL INDIRECT INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSS WHETHER IN CONTRACT TORT OR OTHER WISE Hart Scientific Manual Rev 152301 11 3 Specifications 4 Installation 4 1 Environmental Issues Primary standard equipment should be used in a calibration laboratory or other facility specifically designed for this purpose Environmental re quirements include Stable temperature and humidity Clean draft free area Low noise level low radio frequency magnetic or electrical interfer ence Low vibration levels 4 2 Mounting Most often temperature standards primary and secondary are used to calibrate other temperature sensitive equipment Three representative applications are shown in the f
22. nce with it Your probe should also be checked any time you suspect it may have received mechanical shock or when ever its accuracy appears suspect 1 4 Customer Service Information Hart Scientific can be contacted by writing to Hart Scientific Inc 799 E Utah Valley Drive American Fork UT 84003 9775 Or by calling or faxing Telephone 801 763 1600 Hart Scientific Manual Rev 152301 3 1 Before You Start Fax 801 763 1010 Our World Wide Web site is http www hartscientific com E mail support hartscientific com When calling Hart Scientific Customer Service please have the following information available Model Number Serial Number 4 Manual Rev 152301 5681 5683 5684 5685 1 Before You Start 2 Introduction 2 1 General The Hart Standard Platinum Resistance Thermometer SPRT is de signed to be the best primary standard interpolating instrument convert ing temperature to resistance Hart Scientific offers four models of SPRT probes 5681 5683 5684 and 5685 The Model 5681 fused silica sheathed SPRT covers the International Temperature Scale of 1990 ITS 90 range from the Triple Point of Argon 189 C to the Freezing Point of Aluminum 660 323 C The Model 5683 fused silica sheathed SPRT covers the ITS 90 range from the Triple Point of Argon 189 C to 450 C The limited temperature range of the Model 5683 allows for un beatable long term stability typically less than
23. nsure how to do this A triple of water cell is preferred Ice baths should use distilled water and crushed ice in a Dewar flask or thermos bottle The ratio of ice to water should be such that the mixture is firm after pre pared 3 Set your readout to read in ohms rather than temperature Place your probe in the TPW or ice bath and allow it to stabilize Re member a TPW is at 0 01 C and an ice bath is at 0 C 4 If using a TPW cell compare the resistance value on your read out with the resistance value at TPW given on the probe s certifi cate If using an ice bath compare the resistance value on your readout with the resistance indicated on the certificate for 0 C You may have to use the probe s temperature versus resistance table and interpolate to get the probe s calibrated resistance value at 0 C 5 Considering the probe s uncertainty specification determine whether or not it is within tolerance of the data on its most recent certificate of calibration If it is it may be placed in service If not double check the probe coefficients in the readout If they are correct contact Hart Customer Service Hart recommends that a probe be periodically checked against a stan dard such as a triple point of water cell or well constructed ice bath if an ITS 90 fixed point standard is not available The verification interval de pends on how the probe is handled how and how much it is used and your documented experie
24. ollowing figures Figure 3 Liquid Bath Installation Figure 4 Water Triple Point Cell in an Ice Bath Dewar Figure 5 Hart 9114 Metrology Furnace with SPRT in Fixed Point Cell The SPRT must be mounted carefully to avoid any damage to the sheath or sensor If the fluid bath used does not have a lid designed for SPRT in sertion clamps should be used to ensure the handle and cable are not immersed If metal comparison blocks are used in the bath maintain a close fit between the thermometer sheath and the well in the comparison block However allow for the thermal expansion of the thermometer sheath when determining block well tolerances For applications where the fluid in the bath is not compatible with the SPRT salt the SPRT can be slid into a thin walled metal sheath for pro tection The gap between the protective sheath and the SPRT should not be any larger than 0 003 in 0 08 mm At high temperatures the SPRT is subject to metal ion contamination If a metal equilibration block is used in a furnace above 600 C protective shielding such as thin wall platinum tubing or high purity ceramic is ad vised Hart Scientific Manual Rev 152301 13 4 Installation 14 Manual Rev 152301 5681 5683 5684 5685 4 Installation 7007 Tank with Long Stem SPRTs 24 Figure 3 Liquid Bath Installation Hart Scientific Manual Rev 152301 15 4 Installation Lid Dewar Flask Outer Canister Precooling Ac
25. re of the SPRT may help to reduce electrical noise interference Be sure the ground lead wire is connected to an appropriate ground on the readout device Hart Scientific Manual Rev 152301 29 8 Troubleshooting Problem Solution Temperature read out different than ex pected e g the heat source is set at 300 C the SPRT measures 275 C Measure the SPRT resistance at TPW If the resistance of the SPRT is less than the rated resis tance there may be a short in the sensor Contact Hart Scientific Customer Service If the resistance of the SPRT is only a few ohms there may be a short in the four lead wires Contact Hart Sci entific Customer Service If the SPRT is open the resistance will be Out of Limits or in the kilo ohm or mega ohm range Contact Hart Sci entific Customer Service 30 Manual Rev 152301 5681 5683 5684 5685 8 Troubleshooting
26. rement errors for any thermometer not im mersed in the fluid at least six inches This error is due to heat lost or gained by the sensing element through the thermometer stem In addi tion heat losses occur due to radiation losses from the sensing element to the housing The sand blasted finish on the quartz sheath is designed to depreciate losses due to radiation piping Convection prevention discs provide multiple radiation shields along the lead wires Convection discs and quartz insulation on lead wires causes some shunt resistance at very high temperatures However the effect of the shunt resistance is in significant Full immersion is recommended in a furnace or freeze point cell The immersion depth for primary standards is dependent on several fac tors including accuracy requirements and type of liquid Therefore we recommend an 8 inch minimum immersion depth The exact immersion depth required can be determined by performing a gradient test taking measurements approximately every 1 2 inch 1 27 cm until there is a significant difference in readings Allow the thermome ter to stabilize at each new depth Plot the results to see the stem effect 6 5 Thermal EMF Two factors contribute to thermal EMF chemical consistency and physi cal consistency Variations in chemical structure due to impurities and discrepancies in crystal structure can contribute to thermal EMF These factors are minimized by annealing the full length of wire
27. ure without concern for the cooling rate Hart Scientific Manual Rev 152301 25 6 Operation 7 Accessories 7 1 Case The SPRTS are shipped in a protective case The SPRT should be stored in this case when not in use The SPRT should be shipped in this case when returning see Section 2 5 Return Procedure 7 2 SPRT Termination The 5680 series SPRTs are terminated with gold plated lugs Hart Scientific Manual Rev 152301 27 7 Accessories 8 Troubleshooting 8 1 Troubleshooting In the event that the probe appears to function abnormally this section may help to find and solve the problem Several possible problem condi tions 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 other wise be solved contact Hart Scientific Customer Service for assistance 1 801 763 1600 Be sure to have the model number and serial number of your probe available Problem Solution Data changes Slight mechanical shock can cause temperature errors as much as 2mK If this is observed first measure and record the Rtp Next anneal the SPRT at 661 C 5681 only 480 C 5683 or 975 C 5684 and 5685 overnight 12 hours Measure the Rtp again The annealing should decrease the Rtp Repeat the anneal ing Rtp measurement cycle several times When the Rtp is stable recalibrate the
28. vent before exposure to high temperatures Correct handling of the SPRT will prolong the life ex pectancy When not in use the SPRT should be stored in the protective case provided by Hart 5 2 SPRT Handling Guidelines 1 DO keep the thermometer as clean as possible Always remove any fluid from the sheath immediately after taking the thermometer from a bath To remove any possible contaminants always wipe the sheath with ethyl alcohol or other solvent before submitting the SPRT to high temper atures 2 DO immerse the thermometer in the appropriate liquid for the tempera ture range If a dry block is used the well diameter should allow the SPRT to comfortably slip in and out without excess movement For best results immerse the thermometer as deep as possible to avoid stem ef fect the temperature error caused by the conduction of heat away from the sensor Do not submerge the handles 3 DO allow sufficient time for the thermometer to stabilize before making measurements This allows for the best accuracy Hart Scientific Manual Rev 152101 19 5 Care and Handling Guidelines 4 DO use the correct drive current with the thermometer to prevent error in temperature or resistance 5 DO anneal the thermometer at a temperature slightly higher than the maximum temperature at which the thermometer will be used when it has been subjected to mechanical or temperature shock The SPRT should also be annealed before calibration
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