1、Designation: D3244 07aD3244 12 An American National StandardStandard Practice forUtilization of Test Data to Determine Conformance withSpecifications1This standard is issued under the fixed designation D3244; the number immediately following the designation indicates the year oforiginal adoption or,
2、 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 properties of commercial petroleum products are measured by standardized lab
3、oratory testmethods to check their conformance to specifications. Two or more measurements of the sameproperty of a specific sample by any given test method usually will not give precisely the same answer.Therefore, the test methods generally include a paragraph on the precision of results. This pre
4、cisionis an expression of the reliability of the value of the measured property.Many difficulties that arise in interpreting specifications are due to test imprecision. Because of this,a true value of a property can never be determined exactly; and it is necessary to infer from measuredvalues the ra
5、nge within which the “true value” is likely to lie. The main purpose of this practice is toindicate how test imprecision should be interpreted relative to specification values.1. Scope Scope*1.1 This practice covers guidelines and statistical methodologies with which two parties, usually a supplier
6、and a receiver, cancompare and combine independently obtained test results to obtain an Assigned Test Value (ATV) for the purpose of resolving aproduct quality dispute.1.2 This practice defines a technique for comparing an assignedATV test value with a specification limit.1.3 This practice applies o
7、nly to those test methods which specifically state that the repeatability and reproducibility valuesconform to the definitions herein.1.4 The statistical principles and methodology outlined in this practice can also be used to obtain an ATV for specificationconformance decision when multiple results
8、 are obtained for the same batch of product within a single laboratory. For thisapplication, site precision (R) as defined in Practice D6299 shall be used in lieu of test method published reproducibility (R).2. Referenced Documents2.1 ASTM Standards:2D1319 Test Method for Hydrocarbon Types in Liquid
9、 Petroleum Products by Fluorescent Indicator AdsorptionD4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate
10、Analytical Measure-ment System PerformanceD6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and LubricantsD6792 Practice for Quality System in Petroleum Products and Lubricants Testing LaboratoriesD7372 Guide for Analysis and Interpretation of
11、 Proficiency Test Program ResultsE29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications2.2 ISO Standard:3ISO 4259 Determination and Application of Precision Data in Relation to Methods of Test1 This practice is under the jurisdiction of ASTM Committee D02
12、 on Petroleum Products and Lubricants and is the direct responsibility of D02.94 on CoordinatingSubcommittee on Quality Assurance and Statistics.Current edition approved Nov. 1, 2007Dec. 1, 2012. Published December 2007April 2013. Originally published as an appendix to the 1968 Annual Book of ASTMSt
13、andards, Part 18. Originally approved as a standard in 1974. Last previous edition approved in 2007 as D324407.07a. DOI: 10.1520/D3244-07A.10.1520/D3244-12.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM
14、 Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the us
15、er of an ASTM standard an indication of what changes have been made to the previous version. Becauseit 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 versionof the standard a
16、s published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:3.1.1 acceptance limit (AL),
17、na numerical value that defines the point between acceptable and unacceptable quality.3.1.1.1 DiscussionThe AL is not necessarily the specification limit. It is a value that takes into account the specification value, the test methodprecision, and the confidence level desired for defining minimum ac
18、ceptable quality relative to the specification value.3.1.2 assigned test value (ATV), nthe average of all results obtained in the several laboratories which are consideredacceptable based on the reproducibility of the test method.3.1.3 determination, nthe process of carrying out the series of operat
19、ions specified in the test method whereby a single valueis obtained.3.1.4 dispute, nwhen there is a question as to product quality conformance to specification because a test value obtained fallsoutside the specification limit(s).3.1.5 operator, na person who normally and regularly carries out a par
20、ticular test.3.1.6 precision, nthe degree of agreement between two or more results on the same property of identical test material. In thispractice, precision statements are framed in terms of the repeatability and reproducibility of the test method.3.1.7 receiver, nany individual or organization wh
21、o receives or accepts the product delivered by the supplier.3.1.8 repeatability (r), nquantitative expression of the random error associated with a single operator in a given laboratoryobtaining replicate results with the same apparatus under constant operating conditions on identical test material
22、within a shortperiod of time. It is defined (3.1.8.1) as that difference between two such single results as would be exceeded in the long run inonly 1 case in 20 in the normal and correct operation of the test method (3.1.8.3). (This is known as the 95 % confidence level.)3.1.8.1 DiscussionThe repea
23、tability and reproducibility values should have been determined according to the methods described in ASTM ResearchReport RR:D02-1007, Manual on Determining Precision data forASTM Methods of Petroleum Products and Lubricants,4 PracticeD6300, or ISO 4259.3.1.8.2 DiscussionNot all standards organizati
24、ons define repeatability and reproducibility in precisely these same terms, and attention should alwaysbe paid to definitions before comparing precision values quoted.3.1.8.3 DiscussionThis difference is related to the repeatability or the reproducibility standard deviation but is not the standard d
25、eviation.3.1.9 reproducibility (R), nquantitative expression of the random error associated with operators working in differentlaboratories, each obtaining single results on identical test material when applying the same method. It is defined (3.1.8.1) as thatdifference between two such single and i
26、ndependent results as would be exceeded in the long run in only 1 case in 20 in the normaland correct operation of the test method. See 3.1.8.3.3.1.10 result, nthe value obtained by following the complete set of instructions of a test method. It may be obtained from asingle determination or several
27、determinations, depending on the instruction of the test method.3.1.11 supplier, nany individual or organization responsible for the quality of a product just before it is taken over by thereceiver.3.1.12 test sample, na portion of the product taken at the place where the product is exchanged, that
28、is, where theresponsibility for the product quality passes from the supplier to the receiver. In the event that this is not possible, a suitablesampling location should be mutually agreed upon.3.1.13 true value (), nfor practical purposes, the value towards which the average of single results obtain
29、ed by N laboratoriesusing the same standard test method tends, when N becomes very large. Consequently, this definition of true value is associatedwith the particular test method employed.4 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research
30、Report RR:D02-1007.D3244 1224. Significance and Use4.1 This practice provides a means whereby the parties to a transaction can resolve potential quality disputes over those productproperties which can be tested and expressed numerically.4.1.1 This practice can be used to ensure that such properties
31、are correctly stated on labels or in other descriptions of the product.4.1.2 This practice can be implemented in those cases where a supplier uses an in-house or a commercial testing laboratory tosample and test a product prior to releasing the product to a shipper (intermediate receiver) and the ul
32、timate receiver also uses anin-house or commercial testing laboratory to sample and test the product upon arrival at the destination. The assigned test value(ATV) would still be determined according to 8.3.4.2 This practice can assist in the determination of tolerances from specification limits whic
33、h will ensure that the true value ofa property is sufficiently close to the specification value with a mutually agreed probability so that the product is acceptable to thereceiver. Such tolerances are bounded by an acceptance limit (AL). ( AL). If the ATV value determined by applying this practicefa
34、lls on the AL or on the acceptable side of the AL, the product can be accepted; otherwise it shall be deemed to have failed theproduct acceptance requirement established by applying this practice.4.3 Application of this practice requires the AL be determined prior to actual commencement of testing.
35、Therefore, the degreeof criticality of the specification, as determined by the Probability ofAcceptance (Pvalue) that is required to calculate the AL, shallhave been mutually agreed upon between both parties prior to execution of actual product testing.4.3.1 This agreement should include a decision
36、as to whether the ATV is to be determined by the absolute or rounding-offmethod of Practice E29, as therein defined.4.3.1.1 If the rounding-off method is to be used, the number of significant digits to be retained must also be agreed upon.4.3.1.2 These decisions must also be made in the case where o
37、nly one party is involved, as in the case of a label.4.3.1.3 In the absence of such an agreement, this practice recommends the ATV be rounded in accordance with the rounding-offmethod in Practice E29 to the number of significant digits that are specified in the governing specification.4.4 This pract
38、ice is designed to be suitable for reference in contracts governing the transfer of petroleum products and lubricantsfrom a supplier to a receiver.4.5 As a prerequisite for acceptance for lab test results to be used in this practice, the following conditions shall be satisfied:4.5.1 Long-term standa
39、rd deviation Site precision (R) as defined in Practice D6299 for the appropriate test method(s) from eachlab, as substantiated by in-house quality control programs, on materialfor property typical of the product in dispute, shall bestatistically equivalent or should have a TPI 1.2 (see Practice D679
40、2 for TPI explanation), but at a minimum shall be better thanthe published method standard deviation under reproducibility conditions.reproducibility (R).4.5.2 Each lab shall be able to demonstrate, by way of results from interlaboratory exchange programs, a lack of a systemic biasrelative to exchan
41、ge averages for the appropriate test method(s). method(s) as per methodology outlined in Guide D7372.4.5.3 In the event that the long-term standard deviation for any partys laboratory is not statistically equivalent to each other,site precision of laboratories from two parties are statistically diff
42、erent as confirmed by the F-test (see Annex A4), then, for thepurpose of establishing the assigned test value (ATV,), each laboratorys test result(s)result shall be inversely weighted inaccordance with laboratorys demonstrated variance(s).variance.4.6 It is recommended that this practice be conducte
43、d under the guidance of a qualified statistician.5. Sampling5.1 Sampling should be carried out as specified in accordance with the referenced test method, contract, or specification for thepetroleum product under test, such as Practice D4057, or Practice D4177, or other referenced standards as appro
44、priate. Obtainenough sample to allow for all required determinations to be made. Divide the sample into three secondary samples: a receiversample, a supplier sample, and a retain sample. The retain sample should itself be large enough to permit further subdivision intothree portions in case addition
45、al test work is desirable. made by supplier, receiver, and a possible third party.NOTE 1In the event the contractual or specification-referenced sampling procedure differs from that outlined in the relevant test method, supplier andreceiver need to ensure the correct sampling procedure is used.6. Ap
46、plying Test Method Precision Data to Accept or Reject Test Results6.1 This section describes procedures in which the precision limits of test methods can be used as a decision criterion to acceptor reject test results obtained by two laboratories. This section can also be used for acceptance or reje
47、ction of results of replicatetests by an operator. results.6.2 Significance of Repeatability (r):6.2.1 Acceptance of ResultsWhen only two results are obtained under conditions of repeatability and the difference is equalto or less than the repeatability of the method, the operator may report the ave
48、rage of the two results as being applicable to thesample tested.6.2.2 Rejection of ResultsWhen two results are obtained that differ by more than the repeatability of the method, both shouldbe rejected. Obtain two additional results immediately under conditions of repeatability. If the difference bet
49、ween these two resultsD3244 123is equal to or less than the repeatability of the method, the operator should report the average of the two as being applicable tothe sample tested. If, however, the difference so obtained again exceeds the repeatability, reject the results and investigate theapplication of the method.6.3 Significance of Reproducibility (R):6.3.1 Acceptance of ResultsWhen two results are obtained and comprise one result from each laboratory (Note 12), if thedifference is equal to or less than the reproducibility of the method, then both
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