ASTM_E_2593_-_12.pdf

Designation:E259312Standard Guide forAccuracy Verification of Industrial Platinum ResistanceThermometers1This standard is issued under the fixed designation E2593;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year 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 guide describes the techniques and apparatus re-quired for the accuracy verification of industrial platinumresistance thermometers constructed in accordance with Speci-fication E1137/E1137M and the evaluation of calibrationuncertainties.The procedures described apply over the range of200C to 650C.1.2 This guide does not intend to describe proceduresnecessary for the calibration of platinum resistance thermom-eters used as calibration standards or Standard PlatinumResistance Thermometers.Consequently,calibration of thesetypes of instruments is outside the scope of this guide.1.3 Industrial platinum resistance thermometers are avail-able in many styles and configurations.This guide does notpurport to determine the suitability of any particular design,style,or configuration for calibration over a desired tempera-ture range.1.4 The evaluation of uncertainties is based upon currentinternational practices as described in ISO/TAG 4/WG 3“Guide to the Evaluation of Uncertainty in Measurement”andANSI/NCSL Z540-2-1997“U.S.Guide to the Expression ofUncertainty in Measurement.”1.5 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 to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E344 Terminology Relating to Thermometry and Hydrom-etryE563 Practice for Preparation and Use of an Ice-Point Bathas a Reference TemperatureE644 Test Methods for Testing Industrial Resistance Ther-mometersE1137/E1137M Specification for Industrial Platinum Resis-tance ThermometersE1502 Guide for Use of Fixed-Point Cells for ReferenceTemperaturesE1750 Guide for Use of Water Triple Point Cells2.2 ANSI Publication:ANSI/NCSL Z540-2-1997 U.S.Guide to the Expression ofUncertainty in Measurement32.3 Other Publication:ISO/TAG 4/WG 3 Guide to the Evaluation of Uncertainty inMeasurement3.Terminology3.1 DefinitionsThe definitions given in Terminology E344shall be considered as applying to the terms used in this guide.3.2 Definitions of Terms Specific to This Standard:3.2.1 annealing,va heat treating process intended tostabilize resistance thermometers prior to calibration and use.3.2.2 check standard,na thermometer similar in design tothe unit under test,but of superior stability,which is includedin the calibration process for the purpose of quantifying theprocess variability.3.2.3 coverage factor,nnumerical factor used as a multi-plier of the combined standard uncertainty in order to obtain anexpanded uncertainty.3.2.4 dielectric absorption,nan effect in an insulatorcaused by the polarization of positive and negative chargeswithin the insulator which manifests itself as an in-phasecurrent when the voltage is removed and the charges recom-bine.3.2.5 expanded uncertainty,U,nquantity defining aninterval about the result of a measurement that may beexpected to encompass a large fraction of the distribution ofvalues that could reasonably be attributed to the measurand.1This guide is under the jurisdiction of ASTM Committee E20 on TemperatureMeasurement and is the direct responsibility of Subcommittee E20.03 on ResistanceThermometers.Current edition approved Nov.1,2012.Published December 2012.Originallyapproved in 2007.Last previous edition approved in 2011 as D545611E01.DOI:10.1520/E2593-12.2For 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 standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2.5.1 DiscussionNormally,U is given at a coveragefactor of 2,approximating to a 95%confidence interval.3.2.6 hysteresis,nproperty associated with the resistanceof a thermometer whereby the value of resistance at a tempera-ture is dependant upon previous exposure to different tempera-tures.3.2.7 normal distribution,na frequency distribution char-acterized by a bell shaped curve and defined by two param-eters:mean and standard deviation.3.2.8 platinum resistance thermometer(PRT),na resis-tance thermometer with the resistance element constructedfrom platinum or platinum alloy.3.2.9 rectangular distribution,na frequency distributioncharacteri