ASTM E2536-09
(Guide)Standard Guide for Assessment of Measurement Uncertainty in Fire Tests
Standard Guide for Assessment of Measurement Uncertainty in Fire Tests
SIGNIFICANCE AND USE
Users of fire test data often need a quantitative indication of the quality of the data presented in a test report. This quantitative indication is referred to as the “measurement uncertainty”. There are two primary reasons for estimating the uncertainty of fire test results.
ISO/IEC 17025 requires that competent testing and calibration laboratories include uncertainty estimates for the results that are presented in a report.
Fire safety engineers need to know the quality of the input data used in an analysis to determine the uncertainty of the outcome of the analysis.
SCOPE
1.1 This guide covers the evaluation and expression of uncertainty of measurements of fire test methods developed and maintained by ASTM International, based on the approach presented in the GUM. The use in this process of precision data obtained from a round robin is also discussed.
1.2 The guidelines presented in this standard can also be applied to evaluate and express the uncertainty associated with fire test results. However, it may not be possible to quantify the uncertainty of fire test results if some sources of uncertainty cannot be accounted for. This problem is discussed in more detail in Appendix X2.
1.3 Application of this guide is limited to tests that provide quantitative results in engineering units. This includes, for example, methods for measuring the heat release rate of burning specimens based on oxygen consumption calorimetry, such as Test Method E1354.
1.4 This guide does not apply to tests that provide results in the form of indices or binary results (for example, pass/fail). For example, the uncertainty of the Flame Spread Index obtained according to Test Method E84 cannot be determined.
1.5 In some cases additional guidance is required to supplement this standard. For example, the expression of uncertainty of heat release rate measurements at low levels requires additional guidance and uncertainties associated with sampling are not explicitly addressed.
1.6 This fire standard cannot be used to provide quantitative measures.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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Designation: E2536 − 09 AnAmerican National Standard
Standard Guide for
1
Assessment of Measurement Uncertainty in Fire Tests
This standard is issued under the fixed designation E2536; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The objective of a measurement is to determine the value of the measurand, that is, the physical
quantity that needs to be measured. Every measurement is subject to error, no matter how carefully
it 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 be
used to determine the error of a measurement because the true value is unknown, otherwise a
measurement would not be needed. In fact, the true value of a measurand is unknowable because it
cannot be measured without error. However, it is possible to estimate, with some confidence, the
expected limits of error. This estimate is referred to as the uncertainty of the measurement and
provides 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 uncontrolled
manner. Random errors cannot be eliminated, but their effect on uncertainty is reduced by increasing
the number of repeat measurements and by applying a statistical analysis to the results. Systematic
errors remain unchanged when a measurement is repeated under the same conditions. Their effect on
uncertainty cannot be completely eliminated either, but is reduced by applying corrections to account
for the error contribution due to recognized systematic effects. The residual systematic error is
unknown 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 the
Guide on Uncertainty of Measurements (GUM). Application of the GUM to fire test data presents
some unique challenges. This standard shows how these challenges can be overcome.An example to
illustrate application of the guidelines provided in this standard can be found in Appendix X1.
ε[y 2 Y (1)
where:
ε = measurement error;
y = measured value of the measurand; and
Y = true value of the measurand.
1. Scope presentedintheGUM.Theuseinthisprocessofprecisiondata
obtained from a round robin is also discussed.
1.1 This guide covers the evaluation and expression of
1.2 The guidelines presented in this standard can also be
uncertainty of measurements of fire test methods developed
and maintained byASTM International, based on the approach applied to evaluate and express the uncertainty associated with
firetestresults.However,itmaynotbepossibletoquantifythe
uncertainty of fire test results if some sources of uncertainty
1
ThisguideisunderthejurisdictionofASTMCommitteeE05onFireStandards
cannot be accounted for. This problem is discussed in more
and is the direct responsibility of Subcommittee E05.31 on Terminology and
Services / Functions.
detail in Appendix X2.
Current edition approved Oct. 1, 2009. Published November 2009. Originally
1.3 Application of this guide is limited to tests that provide
approved in 2006. Last previous edition approved in 2006 as E2536-06. DOI:
10.1520/E2536-09. quantitative results in engineering units. This includes, for
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E2536 − 09
example, methods for measuring the heat release rate of obtainedfromthevaluesofanumberofotherquantities,equal
burning specimens based on oxygen consumption calorimetry, to the positive square root of a sum of terms, the terms being
such as Test Method E1354. the variances or covariances of these other quantities weighted
according to how the measurement result varies with changes
1.4 This guide does not apply to tests that provide results in
in these quantities.
the form of indices or binary results (for example, pass/fail).
3.2.3 coverage factor, n—numerical factor used as a multi-
For example, the uncertainty of the Flame Spread Index
plierofthecombinedstandarduncertaintyinordertoobtainan
obtained according to Test Method E84 cannot be determined.
expanded uncertainty.
1.5 In some cases additional guidance is required to supple-
3.2.4 error (of measurement), n—result of a measurement
ment this standard. For example, the expression of uncertainty
minus the true value of the measurand; error consists of two
of hea
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E2536–06 Designation: E2536 – 09
Standard Guide for
1
Assessment of Measurement Uncertainty in Fire Tests
This standard is issued under the fixed designation E2536; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
The objective of a measurement is to determine the value of the measurand, that is, the physical
quantity that needs to be measured. Every measurement is subject to error, no matter how carefully
it 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 be
used to determine the error of a measurement because the true value is unknown, otherwise a
measurement would not be needed. In fact, the true value of a measurand is unknowable because it
cannot be measured without error. However, it is possible to estimate, with some confidence, the
expected limits of error. This estimate is referred to as the uncertainty of the measurement and
provides 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 uncontrolled
manner. Random errors cannot be eliminated, but their effect on uncertainty is reduced by increasing
the number of repeat measurements and by applying a statistical analysis to the results. Systematic
errors remain unchanged when a measurement is repeated under the same conditions. Their effect on
uncertainty cannot be completely eliminated either, but is reduced by applying corrections to account
for the error contribution due to recognized systematic effects. The residual systematic error is
unknown 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 the
Guide on Uncertainty of Measurements (GUM). Application of the GUM to fire test data presents
some unique challenges. This standard shows how these challenges can be overcome.
General principles for evaluating and reporting measurement uncertainties are described in the
Guide on Uncertainty of Measurements (GUM). Application of the GUM to fire test data presents
some unique challenges. This standard shows how these challenges can be overcome.An example to
illustrate application of the guidelines provided in this standard can be found in Appendix X1.
(1) ´[ y 2 Y
where:
´ = measurement error;
y = measured value of the measurand; and
Y = true value of the measurand.
1. Scope
1.1 This guide covers the evaluation and expression of uncertainty of measurements of fire test methods developed and
maintainedbyASTMInternational,basedontheapproachpresentedintheGUM.Theuseinthisprocessofprecisiondataobtained
from a round robin is also discussed.
1.2Application of this guide is limited to tests that provide quantitative results in engineering units.This includes, for example,
methodsformeasuringtheheatreleaserateofburningspecimensbasedonoxygenconsumptioncalorimetry,suchasTestMethod
1.2 Theguidelinespresentedinthisstandardcanalsobeappliedtoevaluateandexpresstheuncertaintyassociatedwithfiretest
results. However, it may not be possible to quantify the uncertainty of fire test results if some sources of uncertainty cannot be
accounted for. This problem is discussed in more detail in Appendix X2.
1
This guide is under the jurisdiction ofASTM Committee E05 on Fire Standards and is the direct responsibility of Subcommittee E05.31 on Terminology and Editorial.
Current edition approved Dec. 1, 2006. Published January 2007. DOI: 10.1520/E2536-06.on Terminology and Services / Functions.
Current edition approved Oct. 1, 2009. Published November 2009. Originally approved in 2006. Last previous edition approved in 2006 as E2536-06. DOI:
10.1520/E2536-09.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
E2536 – 09
1.3 Applicationofthisguideislimitedtoteststhatprovidequantitativeresultsinengineeringunits.Thisincludes,forexample,
methodsformeasuringtheheatreleaserateofburningspecimensbasedonoxygenconsumptioncalorimetry,suchasTestMethod
E1354.
1.3This1.4 Thisguidedoesnotapply
...
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