BS ISO 29473-2012 Fire tests Uncertainty of measurements in fire tests《燃烧试验 燃烧试验中的不确定性测量》.pdf

1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationFire tests Uncertainty of measurements in fire testsBS ISO 29473:2010National forewordThis British Standard is the UK implementation of ISO 29473:2010.The UK participation in its

2、 preparation was entrusted to Technical CommitteeFSH/21, Reaction to fire tests.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions of acontract. Users are responsible for its corre

3、ct application. The British Standards Institution 2012Published by BSI Standards Limited 2012ISBN 978 0 580 63393 5ICS 13.220.01Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of the StandardsPolicy and Strategy

4、Committee on 30 April 2012.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS ISO 29473:2010Reference numberISO 29473:2010(E)ISO 2010INTERNATIONAL STANDARD ISO29473First edition2010-12-01Fire tests Uncertainty of measurements in fire tests Essais au feu Incertitude de m

5、esures dans les essais au feu BS ISO 29473:2010ISO 29473:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed o

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9、hout permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2010 All ri

10、ghts reservedBS ISO 29473:2010ISO 29473:2010(E) ISO 2010 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Terms, definitions and symbols 2 3.1 Terms and definitions .2 3.2 Symbols3 4 Principles .4 5 Evaluating standard uncertainty5 5.1 General .5 5.2

11、 Type A evaluation of standard uncertainty.6 5.3 Type B evaluation of standard uncertainty.6 5.4 Accounting for multiple sources of error .7 6 Determining combined standard uncertainty.7 7 Determining expanded uncertainty .8 8 Reporting uncertainty .9 9 Summary of procedure for evaluating and expres

12、sing uncertainty 10 Annex A (informative) Basic concepts of measurement uncertainty11 Annex B (informative) Uncertainty of fire test results.13 Annex C (informative) Example of estimating the uncertainty in heat release measurements in the cone calorimeter14 Bibliography23 BS ISO 29473:2010ISO 29473

13、:2010(E) iv ISO 2010 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member bo

14、dy interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrot

15、echnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted b

16、y the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent ri

17、ghts. ISO shall not be held responsible for identifying any or all such patent rights. ISO 29473 was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 1, Fire initiation and growth. ISO 29473 is based, with the permission of ASTM International, on ASTM E 2536 Standard Guide for

18、 Assessment of Measurement Uncertainty in Fire Tests, copyright ASTM International. BS ISO 29473:2010ISO 29473:2010(E) ISO 2010 All rights reserved vIntroduction Users of fire test data often need a quantitative indication of the quality of the data presented in a test report. This quantitative indi

19、cation 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 saf

20、ety engineers need to know the quality of the input data used in an analysis to determine the uncertainty of the outcome of the analysis. General principles for evaluating and reporting measurement uncertainties are described in ISO/IEC Guide 98-3:2008. Application of ISO/IEC Guide 98-3:2008 to fire

21、 test data presents some unique challenges. This International Standard shows how these challenges can be overcome. BS ISO 29473:2010INTERNATIONAL STANDARD ISO 29473:2010(E) ISO 2010 All rights reserved 1Fire tests Uncertainty of measurements in fire tests 1 Scope This International Standard gives g

22、uidance on the evaluation and expression of uncertainty of fire test method measurements developed and maintained by ISO/TC 92, based on the approach presented in ISO/IEC Guide 98-3. Application of this International Standard is limited to tests that provide quantitative results in engineering units

23、. This includes, for example, methods for measuring the heat release rate of burning specimens based on oxygen consumption calorimetry, as in ISO 5660-1:2002. This International Standard does not apply to tests that provide results in the form of indices or binary results (e.g. pass/fail). In some c

24、ases, additional guidance will be required to supplement this International Standard. For example, the expression and use of uncertainty at low levels may require additional guidance and uncertainties associated with sampling are not explicitly addressed. NOTE 1 The procedures described in this Inte

25、rnational Standard involve some complex mathematics. Basic concepts of measurement uncertainty are provided in Annex A. NOTE 2 The guidelines presented in this International Standard may also be used to evaluate and express the uncertainty associated with fire test results. However, it is not always

26、 possible to quantify the uncertainty of fire test results as some sources of uncertainty cannot be accounted for. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated refer

27、ences, the latest edition of the referenced document (including any amendments) applies. ISO 5660-1:2002, Reaction-to-fire tests Heat release, smoke production and mass loss rate Part 1: Heat release rate (cone calorimeter method) ISO 5725-2:1994, Accuracy (trueness and precision) of measurement met

28、hods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method ISO 13943, Fire safety Vocabulary ISO/IEC 17025:2005, General requirements for the competence of testing and calibration laboratories ISO/IEC Guide 98-3:2008, Uncertainty

29、 of measurement Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) ISO/IEC Guide 99:2007, International vocabulary of metrology Basic and general concepts and associated terms (VIM) BS ISO 29473:2010ISO 29473:2010(E) 2 ISO 2010 All rights reserved3 Terms, definitions and symbol

30、s For the purposes of this document, the following terms, definitions and symbols apply. 3.1 Terms and definitions 3.1.1 measurement uncertainty uncertainty of measurement uncertainty non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based o

31、n the information used NOTE Adapted from ISO/IEC Guide 99:2007: the Notes are not included here. 3.1.2 standard measurement uncertainty standard uncertainty of measurement standard uncertainty measurement uncertainty expressed as a standard deviation ISO/IEC Guide 99:2007, definition 2.30 3.1.3 Type

32、 A evaluation of measurement uncertainty Type A evaluation evaluation of a component of measurement uncertainty by a statistical analysis of measured quantity values obtained under defined measurement conditions NOTE Adapted from ISO/IEC Guide 99:2007: the Notes are not included here. 3.1.4 Type B e

33、valuation of measurement uncertainty Type B evaluation evaluation of a component of measurement uncertainty determined by means other than a Type A evaluation of measurement uncertainty NOTE Modified from ISO/IEC Guide 99:2007: the Example and Note are not included here. 3.1.5 combined standard meas

34、urement uncertainty combined standard uncertainty standard measurement uncertainty that is obtained using the individual standard measurement uncertainties associated with the input quantities in a measurement model ISO/IEC Guide 99:2007, definition 2.31 3.1.6 expanded measurement uncertainty expand

35、ed uncertainty product of a combined standard measurement uncertainty and a coverage factor one NOTE Adapted from ISO/IEC Guide 99:2007: the Notes are not included here and the definition is slighty modified. BS ISO 29473:2010ISO 29473:2010(E) ISO 2010 All rights reserved 33.1.7 coverage factor numb

36、er larger than one by which a combined standard measurement uncertainty is multiplied to expand the coverage probability to a specified value NOTE 1 A coverage factor is usually symbolized k (see also ISO/IEC Guide 98-3:2008, 2.3.6). NOTE 2 Adapted from ISO/IEC Guide 99:2007. 3.2 Symbols C cone calo

37、rimeter orifice coefficient (m1/2kg1/2K1/2) cisensitivity coefficient of Xif functional relationship between the measurand and the input quantities (Equation 2) k coverage factor m number of sources of error affecting the uncertainty of Xi(Equation 8) N number of input quantities n number of observa

38、tions or measurements Qy is the measured value of the measurand; Y is the true value of the measurand. All terms in Equation (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

39、 a measurement would not be needed. In fact, the true value of a measurand is unknown 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 measurement” and provides a

40、quantitative indication of its quality. Errors of measurement may 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 uncert

41、ainty may be 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 it can be r

42、educed by applying corrections to account for the error contribution due to recognized systematic effects. The residual systematic error is unknown and may be treated as a random error for the purpose of this International Standard. BS ISO 29473:2010ISO 29473:2010(E) ISO 2010 All rights reserved 55

43、Evaluating standard uncertainty 5.1 General A quantitative result of a fire test Y is not normally obtained from a direct measurement, but is determined as a function (f) from N input quantities X1, X2, , XN: 12(, , )NYfXX X= L (2) where Y is measurand; f is the functional relationship between the m

44、easurand; Xiis input quantities (i = 1 N). The input quantities may be categorized as quantities whose values and uncertainties are: directly determined from single observation, repeated observation or judgment based on experience; or brought into the measurement from external sources such as refere

45、nce data obtained from handbooks. An estimate of the output, y, is obtained from Equation (2) using input estimates x1, x2, , xNfor the values of the N input quantities: 12(, , )Nyfxx x= L (3) Substituting Equations (2) and (3) into Equation (1) leads to: 12 NyY Y =+=+ +L (4) where iis the contribut

46、ion to the total measurement error from the error associated with the input estimate xi. A possible approach to determine the uncertainty of y involves a large number (n) of repeat measurements. The mean value of the resulting distribution ()y is the best estimate of the measurand. The experimental

47、standard deviation of the mean is the best estimate of the standard uncertainty of y, denoted by u(y): 222 1()()() ()(1)nkkyysyuy s ynnn=(5) where u is standard uncertainty; s is the experimental standard deviation; n is the number of observations; ykis the kthmeasured value; y is the mean of n meas

48、urements. BS ISO 29473:2010ISO 29473:2010(E) 6 ISO 2010 All rights reservedThe number of observations n should be large enough to ensure that y provides a reliable estimate of the expectation yof the random variable y, and that s2()y provides a reliable estimate of the variance 22() ()/.yy= n NOTE I

49、f the probability distribution of y is normal, then the standard deviation of s ()y relative to ()y is approximately 2(n1)1/2. Thus, for n = 10 the relative uncertainty of ()s y is 24 percent, while for n = 50 it is 10 percent. Additional values are given in Table E.1 in ISO/IEC Guide 98-3:2008. Unfortunately, it is often not feasible or even possible to perform a sufficiently large number of repeat measurements. In those cases, the uncertainty of the measurement can