ASTM D7278-21

Standard Guide for Prediction of Analyzer Sample System Lag Times

SIGNIFICANCE AND USE
5.1 The analyzer sample system lag time estimated by this guide can be used in conjunction with the analyzer output to aid in optimizing control of blender facilities or process units. A known and constant lag time is key for the use in optimizing control.  
5.2 The lag time can be used in the tuning of control programs to set the proper optimization frequency.  
5.3 The application of this guide is not for the design of a sample system but to help understand the design and to estimate the performance of existing sample systems. Additional detailed information can be found in the references provided in the section entitled Additional Reading Material.
SCOPE
1.1 This guide covers the application of routine calculations to estimate sample system lag time, in seconds, for gas, liquid, and mixed phase systems.  
1.2 This guide considers the sources of lag time from the process sample tap, tap conditioning, sample transport, pre-analysis conditioning and analysis.  
1.3 Lag times are estimated based on a prediction of flow characteristics, turbulent, non turbulent, or laminar, and the corresponding purge requirements.  
1.4 Mixed phase systems prevent reliable representative sampling so system lag times should not be used to predict sample representation of a mixed phase stream.  
1.5 The values stated in inch-pound units are to be regarded as standard. Other units of measurement are included in this standard and Appendix X1 examples where normally seen in industry.  
1.6 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.  
1.7 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: 30-Nov-2021
• ICS: 17.220.01 - Electricity. Magnetism. General aspects
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.25 - Performance Assessment and Validation of Process Stream Analyzer Systems

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: D7278 − 21
Standard Guide for
1
Prediction of Analyzer Sample System Lag Times
This standard is issued under the fixed designation D7278; 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
Lag time, as used in this guide, is the time required to transport a representative sample from the
process tap to the analyzer. Sample system designs have infinite configurations so this guide gives the
user guidance, based on basic design considerations, when calculating the lag time of online sample
delivery systems. Lag time of the analyzer sample system is a required system characteristic when
performingsystemvalidationinPracticeD3764,D6122,orD8321andingeneraltheproperoperation
of any online analytical system. The guide lists the components of the system that need to be
considered when determining lag time plus a means to judge the type of flow and need for multiple
flushes before analysis on any sample.
1. Scope* ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This guide covers the application of routine calculations
mendations issued by the World Trade Organization Technical
to estimate sample system lag time, in seconds, for gas, liquid,
Barriers to Trade (TBT) Committee.
and mixed phase systems.
1.2 This guide considers the sources of lag time from the
2. Referenced Documents
process sample tap, tap conditioning, sample transport, pre-
2
2.1 ASTM Standards:
analysis conditioning and analysis.
D3764 Practice forValidation of the Performance of Process
1.3 Lag times are estimated based on a prediction of flow
Stream Analyzer Systems
characteristics, turbulent, non turbulent, or laminar, and the
D6122 Practice for Validation of the Performance of Multi-
corresponding purge requirements.
variate Online, At-Line, Field and Laboratory Infrared
Spectrophotometer, and Raman Spectrometer Based Ana-
1.4 Mixed phase systems prevent reliable representative
lyzer Systems
sampling so system lag times should not be used to predict
D8321 Practice for Development and Validation of Multi-
sample representation of a mixed phase stream.
variate Analyses for Use in Predicting Properties of
1.5 The values stated in inch-pound units are to be regarded
Petroleum Products, Liquid Fuels, and Lubricants based
as standard. Other units of measurement are included in this
on Spectroscopic Measurements
standard and Appendix X1 examples where normally seen in
industry.
3. Terminology
1.6 This standard does not purport to address all of the
3.1 Definitions:
safety concerns, if any, associated with its use. It is the
3.1.1 continuous analyzer unit cycle time, n—the time
responsibility of the user of this standard to establish appro-
interval required to replace the volume of the analyzer mea-
priate safety, health, and environmental practices and deter-
surement cell.
mine the applicability of regulatory limitations prior to use.
3.1.2 intermittent analyzer unit cycle time, n—the time
1.7 This international standard was developed in accor-
interval between successive updates of the analyzer output.
dance with internationally recognized principles on standard-
3.1.3 purge volume, n—the combined volume of the full
analyzer sampling and conditioning systems.
1
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
mittee D02.25 on Performance Assessment and Validation of Process Stream
2
Analyzer Systems. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2021. Published December 2021. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2006. Last previous edition approved in 2016 as D7278 – 16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7278-21. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D7278 − 21
3.1.4 sample system lag time, n—the time required to Highsampleflowratesinsmallsizedcomponentsystemscause
transport a representative sample from the process tap to the high-pressure drops and low sample transport times. The same
analyzer. flowrate
...

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: D7278 − 16 D7278 − 21
Standard Guide for
1
Prediction of Analyzer Sample System Lag Times
This standard is issued under the fixed designation D7278; 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
Lag time, as used in this guide, is the time required to transport a representative sample from the
process tap to the analyzer. Sample system designs have infinite configurations so this guide gives the
user guidance, based on basic design considerations, when calculating the lag time of online sample
delivery systems. Lag time of the analyzer sample system is a required system characteristic when
performing system validation in Practice D3764, D6122or, D6122or D8321 and in general the proper
operation of any online analytical system. The guide lists the components of the system that need to
be considered when determining lag time plus a means to judge the type of flow and need for multiple
flushes before analysis on any sample.
1. Scope*
1.1 This guide covers the application of routine calculations to estimate sample system lag time, in seconds, for gas, liquid, and
mixed phase systems.
1.2 This guide considers the sources of lag time from the process sample tap, tap conditioning, sample transport, pre-analysis
conditioning and analysis.
1.3 Lag times are estimated based on a prediction of flow characteristics, turbulent, non turbulent, or laminar, and the
corresponding purge requirements.
1.4 Mixed phase systems prevent reliable representative sampling so system lag times should not be used to predict sample
representation of the a mixed phase stream.
1.5 The values stated in inch-pound units are to be regarded as standard. No other Other units of measurement are included in this
standard.standard and Appendix X1 examples where normally seen in industry.
1.6 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 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.
1
This guide 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 April 1, 2016Dec. 1, 2021. Published April 2016December 2021. Originally approved in 2006. Last previous edition approved in 20112016 as
D7278 – 11.D7278 – 16. DOI: 10.1520/D7278-16.10.1520/D7278-21.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D7278 − 21
2. Referenced Documents
2
2.1 ASTM Standards:
D3764 Practice for Validation of the Performance of Process Stream Analyzer Systems
D6122 Practice for Validation of the Performance of Multivariate Online, At-Line, Field and Laboratory Infrared
Spectrophotometer, and Raman Spectrometer Based Analyzer Systems
D8321 Practice for Development and Validation of Multivariate Analyses for Use in Predicting Properties of Petroleum
Products, Liquid Fuels, and Lubricants based on Spectroscopic Measurements
3. Terminology
3.1 Definitions:
3.1.1 continuous analyzer unit cycle time—time, n—the time interval required to replace the volume of the analyzer measurement
cell.
3.1.2 intermittent analyzer unit cycle time—time, n—the time interval between successive updates of the analyzer output.
3.1.3 purge volume—volume, n—the combined volume of the full analyzer sampling and conditioning systems.
3.1.4 sample system lag time—time, n—the time required to transport a representative sample from the process tap to the analyzer.
3.1.4.1 Discussion—
This includes sample conditioning unit lag time and sample loop lag time described in Practice D3764.
...