ASTM D7808-12
(Practice)Standard Practice for Determining the Site Precision of a Process Stream Analyzer on Process Stream Material
Standard Practice for Determining the Site Precision of a Process Stream Analyzer on Process Stream Material
SIGNIFICANCE AND USE
4.1 The analyzer site precision is an estimate of the variability that can be expected in a UAR or a PPTMR produced by an analyzer when applied to the analysis of the same material over an extended time period.
4.2 For applications where the process analyzer system results are required to agree with results produced from an independent PTM, a mathematical function is derived that relates the UARs to the PPTMRs. The application of this mathematical function to an analyzer result produces a predicted PPTMR. For analyzers where the mathematical function, that is, a correlation, is developed by D7235, the analyzer site precision of the UARs is a required input to the computation.
4.3 After the correlation relationship between the analyzer results and primary test method results has been established, a probationary validation (see D3764 and D6122) is performed using an independent but limited set of materials that were not part of the correlation activity. This probationary validation is intended to demonstrate that the PPTMRs agree with the PTMRs to within user-specified requirements for the analyzer system application. The analyzer site precision is a required input to the probationary validation procedures.
4.3.1 If the process stream analyzer system and the primary test method are based on the same measurement principle(s), or, if the process stream analyzer system uses a direct and well-understood measurement principle that is similar to the measurement principle of the PTM then validation is done via D3764. Practice D3764 also applies if the process stream analyzer system uses a different measurement technology from the PTM, provided that the calibration protocol for the direct output of the analyzer does not require use of the PTM.
4.3.2 If the process stream analyzer system utilizes an indirect or mathematically modeled measurement principle such as chemometric or multivariate analysis techniques where PTMRs are required for the development of the che...
SCOPE
1.1 This practice describes a procedure to quantify the site precision of a process analyzer via repetitive measurement of a single process sample over an extended time period. The procedure may be applied to multiple process samples to obtain site precision estimates at different property levels
1.1.1 The site precision is required for use of the statistical methodology of D6708 in establishing the correlation between analyzer results and primary test method results using Practice D7235.
1.1.2 The site precision is also required when employing the statistical methodology of D6708 to validate a process analyzer via Practices D3764 or D6122.
1.2 This practice is not applicable to in-line analyzers where the same quality control sample cannot be repetitively introduced.
1.3 This practice is meant to be applied to analyzers that measure physical properties or compositions.
1.4 This practice can be applied to any process analyzer system where the feed stream can be captured and stored in sufficient quantity with no stratification or stability concerns.
1.4.1 The captured stream sample introduction must be able to meet the process analyzer sample conditioning requirements, feed temperature and inlet pressure.
1.4.2 This practice is designed for use with samples that are single liquid phase, petroleum products whose vapor pressure, at sampling and sample storage conditions, is less than or equal to 110 kPa (16.0 psi) absolute and whose D86 final boiling point is less than or equal to 400°C (752°F).Note 1—The general procedures described in this practice may be applicable to materials outside this range, including multiphase materials, but such application may involve special sampling and safety considerations which are outside the scope of this practice.
1.5 The values for operating conditions are stated in SI units and are to be regarded as the standard. The values given in parentheses are the historic...
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Designation: D7808 − 12
Standard Practice for
Determining the Site Precision of a Process Stream
1
Analyzer on Process Stream Material
This standard is issued under the fixed designation D7808; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
When a process stream analyzer is used to monitor or control a process, the results produced by the
analyzer are typically used as surrogates for values that would otherwise have been obtained via
analyses of process samples using a Primary Test Method (PTM). Successful application of the
analyzer requires that the Predicted Primary Test Method Result (PPTMR) produced by the analyzer
agrees with the PrimaryTest Method Result (PTMR) to within some user specified accuracy (bias and
precision). To achieve this goal, it is typically necessary to develop a correlation that relates raw,
UncorrectedAnalyzer Results (UARs) to PTMRs. The correlation and the analyzers performance are
then assessed during the analyzer validation to establish the expected agreement between the PPTMR
and PTMR. In establishing the correlation, and assessing the performance, it is necessary to know the
precision of both the PPTMR and the PTMR. The precision of the PTMRs is typically established
through statistical quality control procedures described in D6299. The precision of the PPTMRs is
established via procedures described herein. The techniques used to determine process analyzer site
precision can also be used for ongoing quality control of the analyzer measurement system.
1. Scope 1.3 This practice is meant to be applied to analyzers that
measure physical properties or compositions.
1.1 This practice describes a procedure to quantify the site
1.4 This practice can be applied to any process analyzer
precision of a process analyzer via repetitive measurement of a
single process sample over an extended time period. The system where the feed stream can be captured and stored in
sufficient quantity with no stratification or stability concerns.
proceduremaybeappliedtomultipleprocesssamplestoobtain
site precision estimates at different property levels 1.4.1 The captured stream sample introduction must be able
to meet the process analyzer sample conditioning
1.1.1 The site precision is required for use of the statistical
methodology of D6708 in establishing the correlation between requirements, feed temperature and inlet pressure.
1.4.2 This practice is designed for use with samples that are
analyzer results and primary test method results using Practice
single liquid phase, petroleum products whose vapor pressure,
D7235.
atsamplingandsamplestorageconditions,islessthanorequal
1.1.2 Thesiteprecisionisalsorequiredwhenemployingthe
to 110 kPa (16.0 psi) absolute and whose D86 final boiling
statisticalmethodologyofD6708tovalidateaprocessanalyzer
point is less than or equal to 400°C (752°F).
via Practices D3764 or D6122.
NOTE 1—The general procedures described in this practice may be
1.2 Thispracticeisnotapplicabletoin-lineanalyzerswhere
applicable to materials outside this range, including multiphase materials,
the same quality control sample cannot be repetitively intro-
but such application may involve special sampling and safety consider-
duced. ations which are outside the scope of this practice.
1.5 ThevaluesforoperatingconditionsarestatedinSIunits
and are to be regarded as the standard. The values given in
1
This test method is under the jurisdiction of ASTM Committee D02 on
parentheses are the historical inch-pound units for information
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.25 on Performance Assessment and Validation of Process Stream Analyzer
only.
Systems.
1.6 This standard does not purport to address all of the
Current edition approved Oct. 1, 2012. Published January 2013. DOI: 10.1520/
D7808-12. safety concerns, if any, associated with its use. It is the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7808 − 12
responsibility of the user of this standard to establish appro- 3.2.4 PTMR(s)—primary test method result(s)
priate safety and health practices and determine the applica-
3.2.5 QC—quality control
bility of regulatory limitations prior to use.
3.2.6 UAR(s)—uncorrected analyzer result(s)
2. Referenced Documents
4. Significance and Use
2
2.1 ASTM Standards:
4.1 The analyzer site precision is an estimate of the vari-
D86 Test Method for Distillation of Petroleum Products at
ability that can be expected
...
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