ASTM D6624-20

Standard Practice for Determining a Flow-Proportioned Average Property Value (FPAPV) for a Collected Batch of Process Stream Material Using Stream Analyzer Data

SIGNIFICANCE AND USE
4.1 Contractual or local regulation, or both, permitting, the FPAPV calculated according to this practice can be used to represent the average property of the quantity of material collected.  
4.2 Due to the averaging and appropriate weighting of analysis results, the FPAPV estimate of the property for the collected material is expected to be more representative and more precise than an estimate based on a small number of analyses on a few samples.
Note 1: For applications where the on-line analyzer system result is being used in direct feedback control in a contiguous manner, the true property distribution for a large population of batches with essentially identical FPAPV's is expected to be Gaussian, centered at the FPAPV value, with a standard deviation that is no less than the long term site precision standard deviation of the analyzer system.  
4.3 If the measured property value is used to predict another property value through the use of an appropriate correlation equation, the FPAPV can also be used as a suitable prediction of that property.  
4.4 The most recently updated FPAPV can be used to represent the property of the material currently accumulated in the tank or vessel for process control or material disposition decisions, or both.
SCOPE
1.1 This practice covers a technique for calculating a flow-proportioned average property value (FPAPV) for a batch of in-line blended product or process stream material that is collected over time and isolated in a storage tank or vessel, using a combination of on-line or at-line measurements taken at regular intervals of the property and flow rates.  
1.2 The FPAPV methodology uses regularly collected on- line or at-line process analyzer measurements, flow, and assessment of other appropriate process measurements or values, to calculate a flow-proportioned average property value in accordance with flow quantity units of material produced.  
1.3 When the collecting vessel contains a heel (retained material prior to receipt of the production batch), both the property value and quantity of the heel material can be predetermined and factored into the calculation of the FPAPV for the new batch.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-May-2020
• ICS: 19.020 - Test conditions and procedures in general
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.25 - Performance Assessment and Validation of Process Stream Analyzer Systems

Relations

• Replaces: ASTM D6624-19 - Standard Practice for Determining a Flow-Proportioned Average Property Value (FPAPV) for a Collected Batch of Process Stream Material Using Stream Analyzer Data
• Effective Date: 01-Jun-2020
• Refers: ASTM D6299-23a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Dec-2023
• Refers: ASTM D5842-23 - Standard Practice for Sampling and Handling of Fuels for Volatility Measurement
• Effective Date: 01-Oct-2023
• Refers: ASTM D6122-23 - Standard Practice for Validation of the Performance of Multivariate Online, At-Line, Field and Laboratory Infrared Spectrophotometer, and Raman Spectrometer Based Analyzer Systems
• Effective Date: 01-Jul-2023
• Refers: ASTM D5842-19 - Standard Practice for Sampling and Handling of Fuels for Volatility Measurement
• Effective Date: 01-Nov-2019
• Refers: ASTM D6122-19b - Standard Practice for Validation of the Performance of Multivariate Online, At-Line, and Laboratory Infrared Spectrophotometer Based Analyzer Systems
• Effective Date: 01-Jun-2019
• Refers: ASTM D6122-19a - Standard Practice for Validation of the Performance of Multivariate Online, At-Line, and Laboratory Infrared Spectrophotometer Based Analyzer Systems
• Effective Date: 01-May-2019
• Refers: ASTM D6122-19 - Standard Practice for Validation of the Performance of Multivariate Online, At-Line, and Laboratory Infrared Spectrophotometer Based Analyzer Systems
• Effective Date: 01-Jan-2019
• Refers: ASTM D6122-18 - Standard Practice for Validation of the Performance of Multivariate Online, At-Line, and Laboratory Infrared Spectrophotometer Based Analyzer Systems
• Effective Date: 01-Jul-2018
• Refers: ASTM D6299-17b - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Dec-2017
• Refers: ASTM D7453-17 - Standard Practice for Sampling of Petroleum Products for Analysis by Process Stream Analyzers and for Process Stream Analyzer System Validation
• Effective Date: 01-Dec-2017
• Refers: ASTM D6299-17a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Nov-2017
• Refers: ASTM D6299-17 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Jan-2017
• Refers: ASTM D3764-15e1 - Standard Practice for Validation of the Performance of Process Stream Analyzer Systems
• Effective Date: 01-Apr-2015
• Refers: ASTM D3764-15 - Standard Practice for Validation of the Performance of Process Stream Analyzer Systems
• Effective Date: 01-Apr-2015

Overview

ASTM D6624-20 is the standard practice for determining a Flow-Proportioned Average Property Value (FPAPV) for a collected batch of process stream material using stream analyzer data. This standard is published by ASTM International and provides a robust methodology for accurately estimating the average properties (such as physical, chemical, or performance values) of materials collected from an in-line blended or process stream over time. The procedure utilizes regular on-line or at-line property measurements and flow rate data to ensure representativeness and precision, making it invaluable for industries where material uniformity and quality assurance are critical.

Key Topics

• Flow-Proportioned Averaging: The core principle is the calculation of a flow-proportioned average property value based on continuous or regularly sampled analyzer data, meticulously weighted by flow quantity. This approach considers material properties as they are introduced into a storage tank or vessel, providing a precise picture of batch quality.
• Integration of Heel Material: When a heel (residual material from previous batches) exists in the collecting vessel, its properties and quantity are accounted for in the FPAPV calculation, ensuring the final average truly represents all collected material.
• Continuous Monitoring and Validation: The standard sets guidelines for ongoing verification and validation of both analytical and flow measurement systems, supporting long-term reliability and system integrity.
• Statistical Assurance: Application of statistical quality control, including the use of control charts and validation against laboratory methods, guarantees data integrity and supports contractual and regulatory compliance.
• Predictive Capability: FPAPV can be used not only for direct property characterization, but also for predictive modeling if appropriate correlation equations exist.

Applications

ASTM D6624-20 is widely used in the petroleum, chemical, and process industries for:

• Blended Product Quality Control: Ensuring the average property value of in-line blended fuels or chemicals meets specifications before transfer or shipment.
• Process Optimization and Control: Leveraging real-time FPAPV data for immediate process adjustments, thereby preventing off-spec production and reducing waste.
• Regulatory Compliance: Providing a scientifically sound basis for reporting average property values to clients or regulators, as permitted by contractual or local regulations.
• Material Disposition Decisions: Using the most recent FPAPV to inform decisions regarding product use, storage, or further processing.
• Sampling Efficiency: Reducing reliance on manual grab sampling, leading to more representative, frequent, and less labor-intensive quality assessments.

This standard is particularly valuable in environments where product homogeneity is critical, such as petroleum terminals, refineries, blending facilities, and chemical plants.

Related Standards

Organizations using ASTM D6624-20 should be aware of and may need to comply with the following related ASTM standards:

• ASTM D3764: Practice for Validation of the Performance of Process Stream Analyzer Systems
• ASTM D4057: Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4177: Practice for Automatic Sampling of Petroleum and Petroleum Products
• ASTM D5842: Practice for Sampling and Handling of Fuels for Volatility Measurement
• ASTM D6122: Practice for Validation of the Performance of Multivariate Online, At-Line, and Laboratory Infrared Spectrophotometer-Based Analyzer Systems
• ASTM D6299: Practice for Applying Statistical Quality Assurance and Control Charting Techniques
• ASTM D7453: Practice for Sampling of Petroleum Products for Analysis by Process Stream Analyzers and for Process Stream Analyzer System Validation

Practical Value

Implementing ASTM D6624-20 enables process operators and quality managers to:

• Obtain more representative and precise property averages for entire batches
• Enhance process control and regulatory compliance through robust, real-time data
• Support decision-making in product quality assurance, custody transfer, and material allocation
• Integrate with industry-accepted practices for sampling, analysis, and quality assurance

This standard supports improved operational efficiency, product consistency, and customer satisfaction across critical process industries.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6624 − 20
Standard Practice for
Determining a Flow-Proportioned Average Property Value
(FPAPV) for a Collected Batch of Process Stream Material
Using Stream Analyzer Data
This standard is issued under the fixed designation D6624; 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 determination of an average property value that is representative of a batch of petroleum
product collected and isolated in a tank or vessel has always been a challenge. Historically, the
industrypracticehasbeentofollowtheappropriateproceduresprescribedinPracticesD4057,D5842,
or D4177 to extract one sample (or a limited few, taken from top, middle, and bottom) from the tank
or vessel after the content is mixed by any of several means to ensure the material is homogeneous
prior to sample extraction. The extracted sample is then sent to a laboratory for analysis. Depending
on the property and its criticality, the average property value can also be obtained by independently
analyzing each of the top, middle, and bottom samples and the results averaged, or, the three tank
samples are mixed and testing for the property is performed on the mixture.
With the introduction of in-line blending and process stream analysis in the 1960s, the potential for
real-time delivery to a pipeline, barge, ship, or tank car compartment was envisioned.
To determine the average property value that is representative of a batch of product from a blend
or process stream, two approaches have been developed and implemented. One depends on the use of
a composite sampler, a vessel into which a sample of the flowing process or blended product stream
is introduced at a flow-rate proportional to the flow-rate of the product stream (Practice D4177 or
D7453). This sample, collected over the period of time required to generate the batch quantity of
product, is then analyzed using a primary test method in the laboratory. Multiple laboratory analyses
on one or more aliquots of composite sample can be averaged to provide a more precise estimate of
the property value than a single analysis.
A second technique utilizes the results produced by on-line, at-line, or in-line analytical
measurement systems that test material from the process or in-line blended stream for the desired
property at regular intervals as it flows to a collection tank, pipeline, or shipping compartment. To
determine the average property value of all the material collected (or shipped) at any time during the
productionprocess,auniquerealtimeflow-proportionedaveragingtechniqueevolved.Byappropriate
selectionofaproductiontimeperiodorcycle,theaveragepropertyvalueforthecollected(orshipped)
material at any time in the production or shipment cycle is obtained by recursively calculating a
flow-proportion average using all available property values from the analytical measurement system
and the measured incremental quantity of product flow associated with each cycle.The determination
of this flow-proportioned average property value is the subject of this practice.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6624 − 20
1. Scope* Measurement System Performance
D7453Practice for Sampling of Petroleum Products for
1.1 This practice covers a technique for calculating a
Analysis by Process Stream Analyzers and for Process
flow-proportionedaveragepropertyvalue(FPAPV)forabatch
Stream Analyzer System Validation
of in-line blended product or process stream material that is
collected over time and isolated in a storage tank or vessel,
3. Terminology
using a combination of on-line or at-line measurements taken
at regular intervals of the property and flow rates.
3.1 Definitions:
3.1.1 analysis cycle time, n—period of time required to
1.2 The FPAPV methodology uses regularly collected on-
properly obtain and analyze a representative sample of the
line or at-line process analyzer measurements, flow, and
process stream material.
assessment of other appropriate process measurements or
values,tocalculateaflow-proportionedaveragepropertyvalue
3.1.2 fit-for-use, n—product, system, or service that is suit-
in accordance with flow quantity units of material produced. able for its intended use.
1.3 When the collecting vessel contains a heel (retained 3.1.3 flow-proportioned average property value (FPAPV),
material prior to receipt of the production batch), both the
n—average property value of the collected material in the tank
property value and quantity of the heel material can be or vessel, calculated by using the flow-proportioned average
predetermined and factored into the calculation of the FPAPV
technique described in the practice of all measurements per-
for the new batch. formed on aliquots of the material while it is flowing into the
tank or vessel.
1.4 This standard does not purport to address all of the
3.1.3.1 Discussion—The term property as used in this prac-
safety concerns, if any, associated with its use. It is the
tice can be the physical, chemical, or performance property
responsibility of the user of this standard to establish appro-
measurements as provided by on-line or at-line analyzer
priate safety, health, and environmental practices and deter-
systems.
mine the applicability of regulatory limitations prior to use.
3.1.3.2 Discussion—The FPAPV can include a property
1.5 This international standard was developed in accor-
value contributed by material (commonly referred to as a tank
dance with internationally recognized principles on standard-
heel) present in the collection tank or vessel before the start of
ization established in the Decision on Principles for the
delivery of the current process stream material. This property
Development of International Standards, Guides and Recom-
value can be determined using the on or at-line measurement
mendations issued by the World Trade Organization Technical
system, or a different measurement system that is suitably
Barriers to Trade (TBT) Committee.
bias-corrected to provide statistically indistinguishable results
2. Referenced Documents
from the on or at-line measurement system.
2.1 ASTM Standards:
3.1.4 linearly mixable, adj—property is deemed to be lin-
D3764PracticeforValidationofthePerformanceofProcess
early mixable in a mass or volume measurement unit if the
Stream Analyzer Systems
property of the mixed material can be calculated from the
D4057Practice for Manual Sampling of Petroleum and
quantities and properties of the materials used to produce the
Petroleum Products
mixture.
D4177Practice for Automatic Sampling of Petroleum and
3.1.4.1 Discussion—The general equations describing this
Petroleum Products
linearly mixable attribute are as follows:
D5842Practice for Sampling and Handling of Fuels for
A ·P 1A ·P 1A ·P 1A ·P 1.1A ·P
1 1 2 2 3 3 4 4 N N
Volatility Measurement
P 5 (1)
MIXED
A 1A 1A 1A 1.1A
1 2 3 4 N
D6122Practice for Validation of the Performance of Multi-
A 5 A 1A 1A 1A 1.1A (2)
variate Online,At-Line, and Laboratory Infrared Spectro- MIXED 1 2 3 4 N
photometer Based Analyzer Systems
where:
D6299Practice for Applying Statistical Quality Assurance
A = quantity of material N,
N
and Control Charting Techniques to Evaluate Analytical
P = property of material N,
N
P = property of mixed material, and
MIXED
A = quantity of mixed material.
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
MIXED
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
3.1.4.2 Discussion—The material being mixed can be from
mittee D02.25 on Performance Assessment and Validation of Process Stream
Analyzer Systems.
the same process stream over time.
Current edition approved June 1, 2020. Published June 2020. Originally
3.1.5 total analyzer system response time, n—time interval
approved in 2001. Last previous edition approved in 2019 as D6624–19. DOI:
10.1520/D6624-20.
between when a step change in property characteristic at the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
sample loop inlet and when the analyzer output indicates a
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
value c corresponding to the 99.5 % of the subsequent change
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. in analyzer results; the total analyzer system response time is
D6624 − 20
the sum of the sample loop lag time, the same conditioning 5.3.4 During the calculation of FPAPV, inferential or other
loop lag time, and the total analyzer response time. D3764 validation strategies shall be in place to ensure the analytical
measurement system results are representative of the material
4. Significance and Use intheprocessstream.Theeffectivenessofthesestrategiesshall
be supported by data.
4.1 Contractual or local regulation, or both, permitting, the
FPAPV calculated according to this practice can be used to
NOTE 2—Examples of these strategies can include, but are not limited
represent the average property of the quantity of material to, the following: monitoring of appropriate system parameters to ensure
each sample is representative of the manufacturing process stream being
collected.
analyzed; continuous comparison of an expected value of the stream
4.2 Due to the averaging and appropriate weighting of
measuredversusactualresult;monitoringforunusuallylargeorunusually
small changes of analytic data; monitoring that property value or spectra
analysis results, the FPAPV estimate of the property for the
are within calibration range; monitoring
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM 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: D6624 − 19 D6624 − 20
Standard Practice for
Determining a Flow-Proportioned Average Property Value
(FPAPV) for a Collected Batch of Process Stream Material
Using Stream Analyzer Data
This standard is issued under the fixed designation D6624; 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
The determination of an average property value that is representative of a batch of petroleum
product collected and isolated in a tank or vessel has always been a challenge. Historically, the
industry practice has been to follow the appropriate procedures prescribed in Practices D4057, D5842,
or D4177 to extract one sample (or a limited few, taken from top, middle, and bottom) from the tank
or vessel after the content is mixed by any of several means to ensure the material is homogeneous
prior to sample extraction. The extracted sample is then sent to a laboratory for analysis. Depending
on the property and its criticality, the average property value can also be obtained by independently
analyzing each of the top, middle, and bottom samples and the results averaged, or, the three tank
samples are mixed and testing for the property is performed on the mixture.
With the introduction of in-line blending and process stream analysis in the 1960s, the potential for
real-time delivery to a pipeline, barge, ship, or tank car compartment was envisioned.
To determine the average property value that is representative of a batch of product from a blend
or process stream, two approaches have been developed and implemented. One depends on the use of
a composite sampler, a vessel into which a sample of the flowing process or blended product stream
is introduced at a flow-rate proportional to the flow-rate of the product stream (Practice D4177 or
D7453). This sample, collected over the period of time required to generate the batch quantity of
product, is then analyzed using a primary test method in the laboratory. Multiple laboratory analyses
on one or more aliquots of composite sample can be averaged to provide a more precise estimate of
the property value than a single analysis.
A second technique utilizes the results produced by on-line, at-line, or in-line analytical
measurement systems that test material from the process or in-line blended stream for the desired
property at regular intervals as it flows to a collection tank, pipeline, or shipping compartment. To
determine the average property value of all the material collected (or shipped) at any time during the
production process, a unique real time flow-proportioned averaging technique evolved. By appropriate
selection of a production time period or cycle, the average property value for the collected (or shipped)
material at any time in the production or shipment cycle is obtained by recursively calculating a
flow-proportion average using all available property values from the analytical measurement system
and the measured incremental quantity of product flow associated with each cycle. The determination
of this flow-proportioned average property value is the subject of this practice.
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.25 on Performance Assessment and Validation of Process Stream Analyzer Systems.
Current edition approved Jan. 1, 2019June 1, 2020. Published January 2019June 2020. Originally approved in 2001. Last previous edition approved in 20142019 as
D6624 – 14.D6624 – 19. DOI: 10.1520/D6624-19.10.1520/D6624-20.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6624 − 20
1. Scope*
1.1 This practice covers a technique for calculating a flow-proportioned average property value (FPAPV) for a batch of in-line
blended product or process stream material that is collected over time and isolated in a storage tank or vessel, using a combination
of on-line or at-line measurements taken at regular intervals of the property and flow rates.
1.2 The FPAPV methodology uses regularly collected on- line or at-line process analyzer measurements, flow, and assessment
of other appropriate process measurements or values, to calculate a flow-proportioned average property value in accordance with
flow quantity units of material produced.
1.3 When the collecting vessel contains a heel (retained material prior to receipt of the production batch), both the property
value and quantity of the heel material can be predetermined and factored into the calculation of the FPAPV for the new batch.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D3764 Practice for Validation of the Performance of Process Stream Analyzer Systems
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D5842 Practice for Sampling and Handling of Fuels for Volatility Measurement
D6122 Practice for Validation of the Performance of Multivariate Online, At-Line, and Laboratory Infrared Spectrophotometer
Based Analyzer Systems
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D7453 Practice for Sampling of Petroleum Products for Analysis by Process Stream Analyzers and for Process Stream Analyzer
System Validation
3. Terminology
3.1 Definitions:
3.1.1 analysis cycle time, n—period of time required to properly obtain and analyze a representative sample of the process
stream material.
3.1.2 fit-for-use, n—product, system, or service that is suitable for its intended use.
3.1.3 flow-proportioned average property value (FPAPV), n—average property value of the collected material in the tank or
vessel, calculated by using the flow-proportioned average technique described in the practice of all measurements performed on
aliquots of the material while it is flowing into the tank or vessel.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3.1.3.1 Discussion—
The term property as used in this practice can be the physical, chemical, or performance property measurements as provided by
on-line or at-line analyzer systems.
3.1.3.2 Discussion—
The FPAPV can include a property value contributed by material (commonly referred to as a tank heel) present in the collection
tank or vessel before the start of delivery of the current process stream material. This property value can be determined using the
on or at-line measurement system, or a different measurement system that is suitably bias-corrected to provide statistically
indistinguishable results from the on or at-line measurement system.
3.1.3 fit-for-use, n—product, system, or service that is suitable for its intended use.
3.1.4 linearly mixable, adj—property is deemed to be linearly mixable in a mass or volume measurement unit if the property
of the mixed material can be calculated from the quantities and properties of the materials used to produce the mixture.
D6624 − 20
3.1.4.1 Discussion—
The general equations describing this linearly mixable attribute are as follows:
A ·P 1A ·P 1A ·P 1A ·P 1.1A ·P
1 1 2 2 3 3 4 4 N N
P 5 (1)
MIXED
A 1A 1A 1A 1.1A
1 2 3 4 N
A 5 A 1A 1A 1A 1.1A (2)
MIXED 1 2 3 4 N
where:
A = quantity of material N,
N
P = property of material N,
N
P = property of mixed material, and
MIXED
A = quantity of mixed material.
MIXED
3.1.4.2 Discussion—
The material being mixed can be from the same process stream over time.
3.1.5 total analyzer system response time, n—time interval between when a step change in property characteristic at the sample
loop inlet and when the analyzer output indicates a value c corresponding to the 99.5 % of the subsequent change in analyzer
results; the total analyzer system response time is the sum of the sample loop lag time, the same conditioning loop lag time, and
the total analyzer response time. D3764
4. Significance and Use
4.1 Contractual or local regulation, or both, permitting, the FPAPV calculated according to this practice can be used to represent
the average property of the quantity of material collected.
4.2 Due to the averaging and appropriate weighting of analysis results, the FPAPV estimate of the property for the collected
material is expected to be more representative and more precise than an estimate based on a small number of analyses on a few
samples.
NOTE 1—For applications where the on-line analyzer system result is being used in direct feedback control in a contiguous manner, the true property
distribution for a large population of batches with essentially identical FPAPV’s is expected to be Gaussian, centered at the FPAPV value, with a standard
deviation that is no less than the long term site precision standard deviation of the analyzer system.
4.3 If the measured property value is used to predict another property value through the use of an appropriate correlation
...