1、Designation: E2820 13Standard Test Method forEvaluating Thermal EMF Properties of Base-MetalThermocouple Connectors1This standard is issued under the fixed designation E2820; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This standard describes a thermal emf test method forbase-metal thermocouple connectors including Types E, J, K,N
3、and T. Standard connectors such as found in SpecificationsE1129/E1129M and E1684 as well as non-standard connectorconfigurations and connector components can be evaluatedusing this method.1.2 The measured emf is reported as an equivalent tempera-ture deviation or error relative to a reference thermo
4、couple ofthe same type. This method can be used to verify deviationsintroduced by the connector greater than or equal to 1C.1.3 The connector is tested with thermocouple contactsaxially aligned with a temperature gradient using a specifiedthermal boundary condition. The actual temperature difference
5、developed across the connector and corresponding error willdepend on the connector design.1.4 Connector contacts are often fabricated from raw mate-rials having temperature-emf relationships in accordance withSpecification E230. However, verifying Specification E230tolerances is not within the scope
6、 of this method.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard t
7、o establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E220 Test Method for Calibration of Thermocouples ByComparison TechniquesE230 Specification and Temperature-Electromotive Force(EMF)
8、 Tables for Standardized ThermocouplesE344 Terminology Relating to Thermometry and Hydrom-etryE563 Practice for Preparation and Use of an Ice-Point Bathas a Reference TemperatureE1129/E1129M Specification for Thermocouple ConnectorsE1684 Specification for Miniature Thermocouple Connec-torsE2488 Guid
9、e for the Preparation and Evaluation of LiquidBaths Used for Temperature Calibration by Comparison3. Terminology3.1 DefinitionsThe definitions given in Terminology E344apply to the terms used in this standard.4. Summary of Test Method4.1 The connector is tested as part of a thermocouple circuitand c
10、ompared to a reference thermocouple of the same typeand material lot.4.2 Measurements are made while the connector is sub-jected to a temperature gradient established by a specifiedboundary condition.4.3 Performance is evaluated at a fixed position within adry-well furnace or stirred liquid bath (Me
11、thod 1 or 2Arespectively) or variable position within a stirred liquid bath(Method 2B). The latter method can be used to survey theconnector to identify a position within the thermal gradient thatproduces a maximum output deviation.4.4 Results are interpreted relative to the properties of thereferen
12、ce thermocouple.5. Significance and Use5.1 A thermocouple connector, exposed to a temperaturedifference, contributes to the output of a thermocouple circuit.The output uncertainty allocated to the connector depends onthe connector design and temperature gradient.5.2 Connector performance can be clas
13、sified based on theresults of this method and used as part of a componentspecification.1This test method is under the jurisdiction of ASTM Committee E20 onTemperature Measurement and is the direct responsibility of Subcommittee E20.04on Thermocouples.Current edition approved May 1, 2013. Published J
14、uly 2013 Originally approvedin 2011. Last previous edition approved in 2011 as E282011. DOI: 10.1520/E282013.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the sta
15、ndards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.3 The method can be used as an engineering tool forevaluating different connector designs tested under similarthermal conditions.6. Appa
16、ratus6.1 The apparatus includes a temperature source, thermo-couple readout device or voltmeter and ice-bath as shown inFig. 1 and Fig. 2.An ice-bath is needed only if the readout doesnot provide cold junction compensation.6.2 The thermocouple readout device or voltmeter shallhave two or more channe
17、ls and have equivalent temperatureresolution of at least 0.1C. The difference between channelsshall not exceed the equivalent of 0.1C when supplied withthe same voltage input.6.3 The temperature source heats the measuring junctionsand produces a temperature gradient across the connector. Thesource i
18、s either a dry-well furnace or stirred liquid bathdepending on the specified method.6.3.1 Method 1a temperature controlled dry-well furnacewith an immersion depth of at least 100 mm and the capabilityof maintaining the specified test temperature within 1C.6.3.2 Method 2a temperature controlled stirr
19、ed liquid bathof non-conductive fluid with an immersion depth of at least 150mm and the capability of maintaining the specified temperaturewithin 1C. Comparison calibration baths as described inGuide E2488 are suitable for this test.7. Hazards7.1 Review the Material Safety Data Sheet (MSDS) beforeus
20、ing a fluid in a temperature-controlled bath. Temperaturelimits, flammability, vapor pressure, toxicity and chemicalstability are important factors in determining a suitable fluid.8. Preparation of Apparatus8.1 The apparatus requires a dual thermocouple circuit witha common measuring junction. The c
21、ircuit shall be fabricatedfrom the same spool of wire. Except for the connector undertest, the length of wire shall be continuous without splices orother connections between the measuring junction and thereadout device.8.2 The thermocouple wire shall carry the same letterdesignation (for example, Ty
22、pe K) as the connector under test.The wire shall conform to the special tolerance in SpecificationE230 over the range of 0C to the maximum specifiedconnector test temperature. The wire size shall be 24 gage (0.5mm) unless specified otherwise.8.3 The test connector shall be installed approximately 70
23、mm from the measuring junction. When testing in a dry-wellfurnace per Method 1, a thermally and electrically insulatinggasket shall be used to seal the furnace entrance, accentuatingthe temperature gradient across the connector. Placing thegasket between the plug and jack is generally the easiest wa
24、yto control the position of the connector within the temperaturegradient (Fig. 3a).8.4 When testing per Method 2 in a liquid bath, theconnector and a portion of the thermocouple shall be attachedto an insulating rod to support the sample during the test (Fig.3b).FIG. 1 Test Schematic Using a Readout
25、 Device with Cold Junction Compensation, Providing Temperature Indications of the Test Ther-mocouple Ttestand Reference Thermocouple TrefE2820 1328.5 The 0C reference junctions (if needed) shall be pre-pared using the same approach used for thermocouple calibra-tion per Test Method E220. The copper
26、wires shall be thermo-couple type TP per Specification E230 and shall all be cut fromthe same spool.8.6 The 0C ice-bath (if needed) shall be prepared inaccordance Practice E563.9. Procedure9.1 Set up the temperature source for the specified testcondition (Table 1).9.2 Connect both thermocouple circu
27、its to the readoutdevice or meter. With the common measuring junction andconnector at room temperature, verify the difference betweencircuits is within the equivalent of 0.1C. For voltage outputs,the difference expressed in C is determined as follows.T 5 Etest2 Eref!/S (1)where:Eref= voltage output
28、of reference thermocouple, mVEtest= voltage output of test thermocouple (with connector),mVS = nominal Seebeck coefficient (see Appendix X1),mV/C9.3 Method 1using a dry-well furnace at fixed depth.FIG. 2 Test Schematic Using a Voltmeter and Reference Junctions at 0CE2820 1339.3.1 Insert the thermoco
29、uples into the furnace with theconnector positioned at the furnace entrance with an insulatinggasket.9.3.2 Adjust the furnace temperature until the referencethermocouple channel indicates the specified test temperaturewithin 6 1C.9.3.3 Allow the thermocouple and connector to equilibrateas indicated
30、by a stable output difference between the referenceand test thermocouples. This typically requires 15 to 30 min,depending on connector design.9.3.4 Record the output of the test and reference thermo-couples.9.4 Method 2Ausing a stirred liquid bath at fixed depth.9.4.1 Insert the thermocouple into th
31、e bath with the connec-tor suspended just above the bath surface (approximately 70mm).9.4.2 Adjust the bath temperature until the referencethermocouple channel indicates the specified test temperaturewithin 6 1C.9.4.3 Lower the thermocouple to the specified connectorimmersion depth.9.4.4 Allow the t
32、hermocouple and connector to equilibrateas indicated by a stable output difference between the referenceand test thermocouples. This typically requires 15 to 30 min,depending on connector design.9.4.5 Record the output of the test and reference thermo-couples.9.5 Method 2Busing a stirred liquid bath
33、 at variabledepth.9.5.1 Insert the thermocouple into the bath with the connec-tor suspended just above the bath surface (approximately 70mm).9.5.2 Adjust the bath temperature until the reference ther-mocouple channel indicates the specified test temperaturewithin 6 1C.9.5.3 Allow the thermocouple an
34、d connector to equilibrateas indicated by a stable output difference between the referenceand test thermocouples. This typically requires 15 to 30 min,depending on connector design.9.5.4 Record the output of the test and reference thermo-couples.9.5.5 Repeat the stabilization step of 9.5.3 and the m
35、easure-ment of 9.5.4 at incrementally increasing depths until theconnector is completely immersed. Each step shall not exceed25 % of the connector length.10. Calculation and Interpretation of Results10.1 The connector error is calculated from the differencebetween the test and reference thermocouple
36、 outputs.10.1.1 When using a temperature readout device:Error 5 Ttest2 Tref(2)where:Ttest= temperature indicated by the test thermocouple (withconnector), CTref= temperature indicated by the reference thermocouple,C10.1.2 When using a voltmeter:FIG. 3 Connector Hook-Up Examples: (a) E1129 Connector
37、Prepared for Method 1 Testing in a Dry-Well Furnace and (b) A Terminal As-sembly Prepared for Method 2 Testing in a Stirred Liquid BathTABLE 1 Standard Test ConditionsCondition Nominal TestTemperature (C)A65B 100C 200D 260or user specifiedE2820 134Error 5 Etest2 Eref!/S (3)where:Etest= output of tes
38、t thermocouple (with connector), mVEref= output of reference thermocouple, mVS = nominal Seebeck coefficient (see Appendix X1),mV/C10.2 The connector error can be positive or negative. Whentesting at a fixed position or depth, the connector error typicallychanges linearly with test temperature as sh
39、own in Fig. 4.10.3 When surveying the connector at multiple immersiondepths (Method 2B), the connector is characterized by themaximum error without regard to sign.10.4 When the connector is completely immersed in thebath, the connector will be approximately isothermal and theresulting error should b
40、e zero.11. Report11.1 The report shall include the following minimum infor-mation:11.1.1 Connector identification,11.1.2 Test method and specified connector immersiondepth, if applicable, and11.1.3 Test condition (Table 1) or specified test temperatureand corresponding connector error expressed in C
41、.12. Precision and Bias12.1 The precision of this test method is based on aninterlaboratory study of ASTM E2820, Standard Test Methodfor Evaluating Thermal EMF Properties of Base Metal Ther-mocouple Connectors, conducted in 2012. Six laboratoriesparticipated in the study, testing three different typ
42、es ofconnectors. Every analyst was instructed to report three repli-cate test results in this study. Practice E691 was followed forthe study design; the details are given in ASTM ResearchReport No. E20-1003.312.1.1 Repeatability limit (r)Two test results obtainedwithin one laboratory shall be judged
43、 not equivalent if theydiffer by more than the “r” value for that material; “r”istheinterval representing the critical difference between two testresults for the same part, obtained by the same operator usingthe same equipment on the same day in the same laboratory.12.1.1.1 Repeatability limits are
44、listed in Table 2.12.1.2 Reproducibility limit (R)Two test results shall bejudged not equivalent if they differ by more than the “R” valuefor that material; “R” is the interval representing the criticaldifference between two test results for the same part, obtainedby different operators using differ
45、ent equipment in differentlaboratories.12.1.2.1 Reproducibility limits are listed in Table 2.12.1.3 The above terms (repeatability limit and reproduc-ibility limit) are used as specified in Practice E177.12.1.4 Any judgment in accordance with statements 12.1.1and 12.1.2 would have an approximate 95
46、% probability ofbeing correct.12.2 BiasAt the time of the study, there was no acceptedreference material suitable for determining the bias for this testmethod; therefore no statement on bias is being made.12.3 The precision statement was determined through sta-tistical examination of 51 test results
47、, from a total of sixlaboratories, on three types of connectors.3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:E20-1003. ContactASTM CustomerService at serviceastm.org.FIG. 4 Example of Connector Error Versus Temperature for an
48、 E1129 Type K Connector Tested per Method 1E2820 13513. Keywords13.1 connector emf; thermocouple connector; thermocouplecontact; thermocouple pin; thermocouple socket; thermocoupleterminalAPPENDIX(Nonmandatory Information)X1. SEEBECK COEFFICIENT CALCULATIONX1.1 The Seebeck coefficient describes the
49、rate of changeof thermal emf with temperature at a given temperature. Thisstandard uses the nominal Seebeck coefficient for the specifiedthermocouple type.X1.2 The Seebeck coefficient can be estimated from thetabulated values of emf versus temperature included in Speci-fication E230.S 5 E22 E1!/T22 T1! (X1.1)where:Tt= nominal test temperature, CT2=Tt+ 1CT1=Tt 1CE2= nominal emf at T2per Specification E230,mVE1= nominal emf at T1per Specification E230,mVX1.2.1 For example, the Seebeck coefficient for a Type Kthermocouple tested at 100C i
