ASTM_E_2536_-_15a.pdf

Designation:E253615aAn American National StandardStandard Guide forAssessment of Measurement Uncertainty in Fire Tests1This standard is issued under the fixed designation E2536;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.INTRODUCTIONThe objective of a measurement is to determine the value of the measurand,that is,the physicalquantity that needs to be measured.Every measurement is subject to error,no matter how carefullyit is conducted.The(absolute)error of a measurement is defined in Eq 1.All terms in Eq 1 have the units of the physical quantity that is measured.This equation cannot beused to determine the error of a measurement because the true value is unknown,otherwise ameasurement would not be needed.In fact,the true value of a measurand is unknowable because itcannot be measured without error.However,it is possible to estimate,with some confidence,theexpected limits of error.This estimate is referred to as the uncertainty of the measurement andprovides a quantitative indication of its quality.Errors of measurement have two components,a random component and a systematic component.The former is due to a number of sources that affect a measurement in a random and uncontrolledmanner.Random errors cannot be eliminated,but their effect on uncertainty is reduced by increasingthe number of repeat measurements and by applying a statistical analysis to the results.Systematicerrors remain unchanged when a measurement is repeated under the same conditions.Their effect onuncertainty cannot be completely eliminated either,but is reduced by applying corrections to accountfor the error contribution due to recognized systematic effects.The residual systematic error isunknown and shall be treated as a random error for the purpose of this standard.General principles for evaluating and reporting measurement uncertainties are described in theGuide on Uncertainty of Measurements(GUM).Application of the GUM to fire test data presentssome unique challenges.This standard shows how these challenges can be overcome.An example toillustrate application of the guidelines provided in this standard can be found in Appendix X1.y 2 Y(1)where:=measurement error;y=measured value of the measurand;andY=true value of the measurand.1.Scope1.1 This guide covers the evaluation and expression ofuncertainty of measurements of fire test methods developedand maintained by ASTM International,based on the approachpresented in the GUM.The use in this process of precision dataobtained from a round robin is also discussed.1.2 The guidelines presented in this standard can also beapplied to evaluate and express the uncertainty associated withfire test results.However,it may not be possible to quantify theuncertainty of fire test results if some sources of uncertaintycannot be accounted for.This problem is discussed in moredetail in Appendix X2.1.3 Application of this guide is limited to tests that providequantitative results in engineering units.This includes,for1This guide is under the jurisdiction ofASTM Committee E05 on Fire Standardsand is the direct responsibility of Subcommittee E05.31 on Terminology andServices/Functions.Current edition approved Oct.1,2015.Published November 2015.Originallyapproved in 2006.Last previous edition approved in 2015 as E2536-15.DOI:10.1520/E2536-15A.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 example,methods for measuring the heat release rate ofburning specimens based on oxygen consumption calorimetry,such as Test Method E1354.1.4 This guide does not apply to tests that provide results inthe form of indices or binary results(for example,pass/fail).For example,the uncertainty of the Flame Spread Indexobtained according to Test Method E84 cannot be determined.1.5 In some cases additional guidance is required to supple-ment this standard.For example,the expression of uncertaintyof heat release rate measurements at low levels requiresadditional guidance and uncertainties associated with samplingare not explicitly addressed.1.6 This fire standard cannot be used to provide quantitativemeasures.1.7 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.2.Referenced Documents2.1 ASTM Standards:2E84 Test Method for Surface Burning Characteristics ofBuilding MaterialsE119 Test Methods for Fire Tests of Building Constructionand MaterialsE176 Terminology of Fire StandardsE230 Specification and Temperature-Electromotive Force(EMF)Tables for Standardized ThermocouplesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1354 Test Method for Heat and Visible Smoke ReleaseRates for Materials and Products Using an Oxygen