ASTM D7278-16
(Guide)Standard Guide for Prediction of Analyzer Sample System Lag Times
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.
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 the stream.
1.5 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D7278 − 16
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 or D6122 and in general the proper operation of any
onlineanalyticalsystem.Theguideliststhecomponentsofthesystemthatneedtobeconsideredwhen
determining lag time plus a means to judge the type of flow and need for multiple flushes before
analysis on any sample.
1. Scope* 2. Referenced Documents
2
1.1 This guide covers the application of routine calculations 2.1 ASTM Standards:
to estimate sample system lag time, in seconds, for gas, liquid, D3764 Practice forValidation of the Performance of Process
and mixed phase systems. Stream Analyzer Systems
D6122 Practice for Validation of the Performance of Multi-
1.2 This guide considers the sources of lag time from the
variate Online,At-Line, and Laboratory Infrared Spectro-
process sample tap, tap conditioning, sample transport, pre-
photometer Based Analyzer Systems
analysis conditioning and analysis.
1.3 Lag times are estimated based on a prediction of flow
3. Terminology
characteristics, turbulent, non turbulent, or laminar, and the
3.1 Definitions:
corresponding purge requirements.
3.1.1 continuous analyzer unit cycle time—the time interval
1.4 Mixed phase systems prevent reliable representative
required to replace the volume of the analyzer measurement
sampling so system lag times should not be used to predict cell.
sample representation of the stream.
3.1.2 intermittent analyzer unit cycle time—thetimeinterval
between successive updates of the analyzer output.
1.5 The values stated in inch-pound units are to be regarded
as standard. No other units of measurement are included in this
3.1.3 purge volume—the combined volume of the full ana-
standard.
lyzer sampling and conditioning systems.
1.6 This standard does not purport to address all of the
3.1.4 sample system lag time—the time required to transport
safety concerns, if any, associated with its use. It is the
a representative sample from the process tap to the analyzer.
responsibility of the user of this standard to establish appro-
3.1.5 system response time—the sum of the analyzer unit
priate safety and health practices and determine the applica-
response time and the analyzer sample system lag time.
bility of regulatory limitations prior to use.
3.2 Abbreviations:
1 3.2.1 I.D.—Internal Diameter
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 April 1, 2016. Published April 2016. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2006. Last previous edition approved in 2011 as D7278 – 11. DOI: Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
10.1520/D7278-16.
*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 − 16
3.2.2 Re—Reynolds Number liquids, the selection and location of pressure regulating
devices in the vapor sample system has a significant impact on
4. Summary
the overall system design. The optimal location for a high-
pressure regulator in a vapor sample is immediately down-
4.1 The lag time of an analyzer sample system is estimated
stream of the sample tap or high-pressure location thereby
by first determining the flow characteristics. The flow is
limiting the volume of the system under high pressure. Since
assigned as turbulent or non-turbulent to assign the number of
thedensityofacompressiblefluidisafunctionofthepressure,
purges required to change out the sample. Based on the
compressible fluid flow rate calculations are sometimes done
hardware employed in the sample syste
...
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 − 11 D7278 − 16
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 or D6122 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 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 stream.
1.5 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this
standard.
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 and health practices and determine the applicability of regulatory
limitations prior to use.
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, and Laboratory Infrared Spectrophotometer
Based Analyzer Systems
3. Terminology
3.1 Definitions:
3.1.1 continuous analyzer unit cycle time—the time interval required to replace the volume of the analyzer measurement cell.
3.1.2 intermittent analyzer unit cycle time—the time interval between successive updates of the analyzer output.
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 Oct. 15, 2011April 1, 2016. Published December 2011April 2016. Originally approved in 2006. Last previous edition approved in 20062011 as
D7278D7278 – 11.–06. DOI: 10.1520/D7278-11.10.1520/D7278-16.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on 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
---------------------- Page: 1 ----------------------
D7278 − 16
3.1.3 purge volume—the combined volume of the full analyzer sampling and conditioning systems.
3.1.4 sample system lag time—the time required to transport a representative sample from the process tap to the analyzer.
3.1.5 system response time—the sum of the analyzer unit response time and the analyzer sample system lag time.
3.2 Abbreviations:
3.2.1 I.D.—Internal Diameter
3.2.2 Re—Reynolds Number
4. Summary
4.1 The lag time of an analyzer sample system is estimated by first determining the flow characteristics. The flow is assigned
as turbulent or non-turbulent to assign the number of purges required to change out the sample. Based on the hardware employed
in the sample system an estimation of the lag time can be calculated.
5. Significance and Use
5.1 The analyzer sample system lag time
...
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