1、Designation: D7235 10Standard Guide forEstablishing a Linear Correlation Relationship BetweenAnalyzer and Primary Test Method Results Using RelevantASTM Standard Practices1This standard is issued under the fixed designation D7235; the number immediately following the designation indicates the year o
2、foriginal 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.INTRODUCTIONOperation of a process stream analyzer system typically in
3、volves four sequential activities: (1)Analyzer CalibrationWhen an analyzer is initially installed, or after major maintenance has beenperformed, diagnostic testing will typically be performed to demonstrate that the analyzer meetsmanufacturers specifications and historical performance standards. The
4、se diagnostic tests may requirethat the analyzer be adjusted so as to provide predetermined output levels for certain referencematerials. (2) Correlation to Primary Test MethodFor process stream analyzer systems where theapplication objective is to provide prediction of results from a Primary Test m
5、ethod, once thediagnostic testing is completed, process stream samples will typically be analyzed using both theanalyzer system and the corresponding primary test method. A mathematical function will be derivedthat relates the analyzer output to the primary test method (PTM). The application of this
6、 mathematicalfunction to an analyzer output produces a predicted PTM result. (3) Initial ValidationOnce therelationship between the analyzer output and primary test method results has been established, aninitial validation is performed using an independent data set to demonstrate that the predicted
7、PTMresults agree with those from the primary test method within the tolerances established from theCorrelation activities and with no statistically observable systemic bias. (4) Continual ValidationDuring normal operation of the process analyzer system, quality assurance testing is conducted todemon
8、strate that the agreement between analyzer and primary test method results during the InitialValidation is maintained. This document provides guidance for item (2) above.1. Scope1.1 This guide covers a general methodology to develop andassess the linear relationship between results produced by atota
9、l analyzer system versus the results produced by thecorresponding primary test method (PTM) that the analyzersystem is intended to emulate, using the principles and ap-proaches outlined in relevant ASTM standard practices andguides.1.2 This guide describes how the statistical methodology ofPractice
10、D6708 can be employed to assess agreement betweenthe PTM and analyzer results, and, if necessary, develop linearcorrelation to further improve the agreement over the completeoperating range of the analyzer. For instances where there isinsufficient variation in property level to apply the PracticeD67
11、08 multi-level methodology, users are referred to PracticeD3764 to perform a level specific bias evaluation. The corre-lation relationship information obtained in the application ofthis guide is applicable only to the material type and propertyrange of the materials representative of those used to p
12、erformthe assessment. Users are cautioned against extrapolation ofthe relationship beyond the material type and property rangebeing studied.1.3 This guide applies if the process stream analyzer systemand the primary test method are based on the same measure-ment principle(s), or, if the process stre
13、am analyzer systemuses a direct and well-understood measurement principle that issimilar to the measurement principle of the primary testmethod. If the process stream analyzer system uses a different1This guide is under the jurisdiction of ASTM Committee D02 on PetroleumProducts and Lubricants and i
14、s the direct responsibility of Subcommittee D02.25 onPerformance Assessment and Validation of Process Stream Analyzer Systems.Current edition approved July 1, 2010. Published October 2010. Originallyapproved in 2005. Last previous edition approved in 2005 as D723505. DOI:10.1520/D7235-10.1Copyright
15、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.measurement technology from the primary test method, pro-vided that the calibration protocol for the direct output of theanalyzer does not require use of the PTM, this practice alsoapplies.1.4 Thi
16、s guide does not apply if the process stream analyzersystem utilizes an indirect or mathematically modeled mea-surement principle such as chemometric or multivariate analy-sis techniques where results from PTM are required for thechemometric or multivariate model development. Users shouldrefer to Pr
17、actices E1655 and D6122 for detailed correlation andmodel validation procedures for these types of analyzer sys-tems.NOTE 1For example, this guide would apply for the comparison ofbenzene measurements from a mid-infrared process analyzer system basedon Test Method D6277 to those obtained using PTM T
18、est Method D3606,a gas chromatography based test method. For each sample, the mid-infrared spectrum is converted into a single analyzer result using meth-odology (Test Method D6277) that is independent of the primary testmethod (Test Method D3606). However, when the same analyzer uses amultivariate
19、model to correlate the measured mid-infrared spectrum toTest Method D3606 reference values using the methodology of PracticeE1655, this guide does not apply. In this case, the direct output of theanalyzer is the spectrum, and the conversion of this multivariate output toan analyzer result require re
20、sults from the primary test method.1.5 This guide assumes that the analyzer sampling system isfit for use, and both analyzer and lab systems are in statisticalcontrol during the execution of the required tasks. Proceduresfor testing for proper function of the analyzer sampling systemare beyond the s
21、cope of this guide. For ascertaining whetherthe systems are in statistical control, refer to Practice D6299 orother technical equivalent documents.1.6 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 sta
22、ndard 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:2D3606 Test Method for Determination of Benzene andToluene in Finished Motor and Aviation Gasoline by GasChromatographyD3764 P
23、ractice for Validation of the Performance of Pro-cess Stream Analyzer SystemsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD5191 Test Method for Vapor Pressure of Petroleum Prod-ucts (Mini Method)D6122 Practice for Validation of the Performance of Mul-tivariate Online, At-L
24、ine, and Laboratory Infrared Spec-trophotometer Based Analyzer SystemsD6277 Test Method for Determination of Benzene in Spark-Ignition Engine Fuels Using Mid Infrared SpectroscopyD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasuremen
25、t System PerformanceD6624 Practice for Determining a Flow-Proportioned Av-erage Property Value (FPAPV) for a Collected Batch ofProcess Stream Material Using Stream Analyzer DataD6708 Practice for StatisticalAssessment and Improvementof Expected Agreement Between Two Test Methods thatPurport to Measu
26、re the Same Property of a MaterialE1655 Practices for Infrared Multivariate QuantitativeAnalysis2.2 American Petroleum Institute Document:3API TP-550 Manual on Installation of Refinery Instrumentsand Control Systems, Part II, Process Stream Analyzers3. Terminology3.1 All of the terminology as define
27、d in Practices D3764,D6122, and D6708 are adopted for this guide.3.2 Definitions of Terms Specific to This Standard:3.2.1 primary test method (PTM), ntest method desig-nated by the user of this guide such that the process analyzersystem results are estimates or prediction of PTM results thatwould ha
28、ve been obtained if applied to the same material.3.2.1.1 DiscussionIt is not the intent of this guide todefine a test method. Within the context of the intendedapplication of this practice, a PTM can be any user-designatedtest method that the process analyzer system test results areintended to estim
29、ate or predict.4. Significance and Use4.1 This guide is intended to be used in conjunction withPractice D3764 (Case 1) and Practice D6122 (Case 2). Meth-odology in this guide can be used to determine if a linearcorrelation can improve the performance of the total analyzersystem in terms of its abili
30、ty to predict the results that the PTMwould have been if applied to the same material. This meth-odology, which is based on the same statistical data treatmentas Practice D6708, is use to derive the parameters of the linearrelationship and to assess the degree of improvement.4.2 This guide provides
31、developers or manufacturers ofprocess stream analyzer systems with useful procedures fordeveloping the capability of newly designed systems forindustrial applications that require reliable prediction of mea-surements of a specific property by a primary test method of aflowing component or product.4.
32、3 This guide provides purchasers of process stream ana-lyzer systems with some reliable options for specifying perfor-mance requirements for process stream analyzer systems thatare used in applications requiring reliable prediction of mea-surements of a specific property by a primary test method of
33、aflowing component or product.4.4 This guide provides the user of a process streamanalyzer system with useful information on the work processfor establishing the PTM prediction relationship and predictionperformance.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM
34、 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 Petroleum Institute (API), 1220 L. St., NW, Wash-ington, DC 20005-4070, http:/www.api.org.D7235 1024.5 Prediction (corre
35、lation) relationship obtained in theapplication of this guide is applicable only to the material typeand property range of the materials used to perform the study.Selection of the property levels and the compositional charac-teristics of the samples must be suitable for the application ofthe analyze
36、r system. Users are cautioned against extrapolationof the prediction relationship beyond the material type andproperty range used to obtain the relationship.4.6 The degree-of-agreement assessment promoted in thisguide is based on the statistical principles articulated inPractice D6708, which is pure
37、ly statistical in nature. Noattempt is made in assessing the degree of similarity in theanalytical technique between the process analyzer and thePTM; hence, results between the PTM and analyzer unit can behighly correlated, but their measurement principles may becompletely different, and may not be
38、the principal cause forcorrelation. Users are therefore cautioned that a high degree ofcorrelation between results does not necessarily imply a highdegree of similarity in the measurement principles; nor does itimply a similar degree of agreement can be expected in futuremeasurements. In general, if
39、 sample-specific biases are de-tected, it suggests that the measurement principles may bedifferent, and may affect the degree-of-agreement in future useof the scaling/bias-correction equation. Presence or absence ofsample-specific effect can be used as a measure of therobustness of the correlation e
40、quation to sample composition ormatrix differences.4.7 Implementation of this guide requires that the processstream analyzer system complies with the following condi-tions:4.7.1 Meets the principles set forth in PART II ProcessStream Analyzers of API TP-550,4.7.2 Meets the suppliers recommendation,4
41、.7.3 Complies with operating conditions specified by themanufacturer,4.7.4 A predicted PTM algorithm has already been estab-lished if necessary, and4.7.5 Meets applicable quality assurance, data collectionand data telemetry protocols.4.8 After installation or major maintenance, conduct suchdiagnosti
42、c tests as recommended by the manufacturer todemonstrate that the analyzer meets manufacturers specifica-tions, historical performance levels or both. If necessary, adjustthe analyzer system components so as to obtain recommendedanalyzer output levels for specified reference materials.4.9 Inspect th
43、e entire analyzer system to ensure it is in-stalled properly, is in operating condition, and is properlyadjusted after completion of the initial commissioning proce-dures.5. Analyzer Calibration Adjustments and DiagnosticsTests5.1 When an analyzer is initially installed or after majormaintenance has
44、 been performed, diagnostic tests should beconducted to demonstrate that the analyzer meets manufactur-ers specifications and historical performance standards. Thesediagnostic tests may require that the analyzer be adjusted so asto provide predetermined output levels for certain referencematerials.
45、Such adjustment may be done in hardware, softwareor both. This should not be confused with the development ofcorrelation to a PTM, which, is described below.6. Correlation to Primary Test Method6.1 General Approach:6.1.1 Define the sample set to be used for assessment.6.1.1.1 The material type and p
46、roperty range for which theanalyzer system results are to be assessed versus the primarytest method is defined.6.1.1.2 The recommended sample set design criteria for thisassessment are:(1) A minimum of six replicates at each major product/property level combination,(2) The range of major product/pro
47、perty levels exceed atleast two times the published reproducibility of the PTM, and(3) A minimum of 30 total samples.6.1.1.3 Replication at a specific level/product combinationcan be different batches of production material that are nomi-nally similar in property level (within 1.2 times the ASTMrepr
48、oducibility of the PTM) and composition.6.1.2 Obtain site precision information for the analyzersystem and PTM for the material type and range defined inaccordance with the procedures outlined in Practice D6299.Ifanalyzer system precision cannot be obtained using the meth-odology in Practice D6299,
49、manufacturers published repeat-ability precision or site precision from other similar systemsmay be used as a surrogate. Users are cautioned to ensureconsistency in statistical definitions between the manufactur-ers published repeatability and the site precision statistic asdefined in Practice D6299.SAMPLING METHOD6.1.3 Line Sampling (Preferred)Samples meeting the re-quirements of the sample set design criteria above are taken inaccordance with Practice D3764, Line Sample Procedure, atthe crosscheck sample points of the analyzer system (see Fig.1), after the sample con
