ASTM D7164-21

Standard Practice for On-line/At-line Heating Value Determination of Gaseous Fuels by Gas Chromatography

SIGNIFICANCE AND USE
5.1 On-line, at-line, in-line, and other near-real time monitoring systems that measure fuel gas characteristics such as the heating value are prevalent in the natural gas and fuel gas industries. The installation and operation of particular systems vary on the specific objectives, process type, regulatory requirements, and internal performance requirements needed by the user. This protocol is intended to provide guidelines for standardized start-up procedures, operating procedures, and quality assurance practices for on-line, at-line, in-line, and other near-real time heating value monitoring systems.
SCOPE
1.1 This practice is for the determination of heating value in high methane content gaseous fuels such as natural gas using an on-line/at-line gas chromatograph.  
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 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.  
1.4 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-Mar-2021
• ICS: 75.160.30 - Gaseous fuels
• Technical Committee: D03 - Gaseous Fuels
• Drafting Committee: D03.12 - On-Line/At-Line Analysis of Gaseous Fuels

Relations

• 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 D4626-23 - Standard Practice for Calculation of Gas Chromatographic Response Factors
• 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 D4150-19 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 15-Dec-2019
• Refers: ASTM D4626-95(2019) - Standard Practice for Calculation of Gas Chromatographic Response Factors
• Effective Date: 01-Dec-2019
• Refers: ASTM E260-96(2019) - Standard Practice for Packed Column Gas Chromatography
• Effective Date: 01-Sep-2019
• Refers: ASTM E594-96(2019) - Standard Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
• Effective Date: 01-Sep-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 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 D4150-08(2016) - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 01-Jul-2016

Overview

ASTM D7164-21 is the internationally recognized standard practice for the on-line and at-line determination of the heating value of high methane content gaseous fuels, such as natural gas, using gas chromatography. Developed by ASTM International, this standard provides comprehensive guidelines for system installation, operation, and quality assurance of monitoring systems designed for continuous or near-real-time analysis of fuel gas heating value. Accurate determination of heating value is essential for energy measurement, process control, and compliance with regulatory and contractual requirements in the natural gas and fuel gas sectors.

Key Topics

• Scope and Purpose

  • Application to on-line, at-line, and in-line gas chromatographic systems for direct or semi-continuous measurement of heating value in natural gas and similar fuels
  • Establishment of standardized practices for start-up, operation, and routine maintenance
  • Focus on high-methane-content gaseous fuels

• System Requirements

  • Use of gas chromatographs equipped for reliable sample extraction, conditioning, and analysis
  • Emphasis on proper siting and installation to minimize sampling lag and maintain sample integrity
  • Use of certified calibration and reference gas mixtures for validation and calibration checks

• Quality Assurance

  • Detailed recommendations for performance tests, including calibration checks, linearity testing, drift assessments, and comparison with laboratory results
  • Implementation of robust maintenance protocols, including logging and pretest verifications
  • Continuous or periodic validation against established standards to ensure long-term data accuracy

• Safety and Compliance

  • Guidance for operators to establish and maintain necessary health, safety, and environmental practices
  • Alignment with international standardization principles for global applicability

Applications

The practical value of ASTM D7164-21 spans multiple industry applications:

• Process Control

  • Real-time monitoring of heating value ensures optimized combustion performance in gas turbines, boilers, and other gas-fueled process equipment
  • Immediate response to changes in gas quality, supporting process adjustments and efficiency improvements

• Custody Transfer and Billing

  • Accurate determination of heating value supports fair and transparent transactions between gas producers, transporters, and end-users
  • Compliance with contractual and regulatory requirements for energy content measurement

• Regulatory Monitoring

  • Assists operators in meeting national and international regulations governing fuel gas composition, safety, and emissions
  • Provides a consistent framework for reporting and validation of results

• Quality Control

  • Ensures the integrity of data used for product quality assessments, reporting, and certification
  • Enables detection of contamination or inconsistencies in gas composition

Related Standards

ASTM D7164-21 references several other important standards to support holistic measurement and assurance practices:

• ASTM D1945: Analysis of Natural Gas by Gas Chromatography
• ASTM D3588: Calculating Heat Value, Compressibility Factor, and Relative Density of Gaseous Fuels
• ASTM D3764: Validation of the Performance of Process Stream Analyzer Systems
• ASTM D4150: Terminology Relating to Gaseous Fuels
• ASTM D4626: Calculation of Gas Chromatographic Response Factors
• ISO 6976: Natural Gas – Calculation of Calorific Values, Density, Relative Density, and Wobbe Indices From Composition
• GPA 2172: Calculation of Gross Heating Value, Relative Density, Compressibility, and Theoretical Hydrocarbon Liquid Content for Natural Gas Mixtures for Custody Transfer

Summary

Adopting ASTM D7164-21 for the determination of heating value by gas chromatography supports gas industry stakeholders in achieving reliable, repeatable, and standardized measurement of energy content in natural gas. The standard's protocols promote best practices in system installation, operation, calibration, and maintenance, ensuring compliance, accuracy, and operational efficiency across natural gas production, processing, and distribution.

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: D7164 − 21
Standard Practice for
On-line/At-line Heating Value Determination of Gaseous
Fuels by Gas Chromatography
This standard is issued under the fixed designation D7164; 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.
1. Scope D5287 Practice for Automatic Sampling of Gaseous Fuels
D5503 Practice for Natural Gas Sample-Handling and Con-
1.1 This practice is for the determination of heating value in
ditioning Systems for Pipeline Instrumentation (With-
high methane content gaseous fuels such as natural gas using
drawn 2017)
an on-line/at-line gas chromatograph.
D6122 Practice for Validation of the Performance of Multi-
1.2 Units—The values stated in SI units are to be regarded
variate Online, At-Line, Field and Laboratory Infrared
as standard. No other units of measurement are included in this
Spectrophotometer, and Raman Spectrometer BasedAna-
standard.
lyzer Systems
1.3 This standard does not purport to address all of the
D6299 Practice for Applying Statistical Quality Assurance
safety concerns, if any, associated with its use. It is the and Control Charting Techniques to Evaluate Analytical
responsibility of the user of this standard to establish appro-
Measurement System Performance
priate safety, health, and environmental practices and deter- D6621 Practice for Performance Testing of Process Analyz-
mine the applicability of regulatory limitations prior to use.
ers for Aromatic Hydrocarbon Materials
1.4 This international standard was developed in accor- D7833 Test Method for Determination of Hydrocarbons and
dance with internationally recognized principles on standard-
Non-Hydrocarbon Gases in Gaseous Mixtures by Gas
ization established in the Decision on Principles for the Chromatography
Development of International Standards, Guides and Recom-
E260 Practice for Packed Column Gas Chromatography
mendations issued by the World Trade Organization Technical E594 Practice for Testing Flame Ionization Detectors Used
Barriers to Trade (TBT) Committee.
in Gas or Supercritical Fluid Chromatography
E1510 Practice for Installing Fused Silica Open Tubular
2. Referenced Documents
Capillary Columns in Gas Chromatographs
2.1 ASTM Standards:
2.2 ISO Standards
D1070 Test Methods for Relative Density of Gaseous Fuels
ISO 6976 Natural Gas — Calculation of Calorific Values,
D1945 Test Method for Analysis of Natural Gas by Gas
Density, Relative Density and Wobbe Indices From Com-
Chromatography
position
D1946 Practice for Analysis of Reformed Gas by Gas
ISO 7504 Gas Analysis-Vocabulary
Chromatography 5
2.3 Gas Processors Association Standards:
D3588 Practice for Calculating Heat Value, Compressibility
GPA 2172 Calculation of Gross Heating Value, Relative
Factor, and Relative Density of Gaseous Fuels
Density, Compressibility and Theoretical Hydrocarbon
D3764 Practice forValidation of the Performance of Process
Liquid Content for Natural Gas Mixtures for Custody
Stream Analyzer Systems
Transfer
D4150 Terminology Relating to Gaseous Fuels
D4626 Practice for Calculation of Gas Chromatographic
3. Terminology
Response Factors
3.1 For definitions of general terms used in D03 Gaseous
Fuels standards, refer to Terminology D4150.
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous
Fuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-Line
Analysis of Gaseous Fuels.
Current edition approved April 1, 2021. Published May 2021. Originally The last approved version of this historical standard is referenced on
approved in 2005. Last previous edition approved in 2015 as D7164 – 10(2015). www.astm.org.
DOI: 10.1520/D7164-21. Available from International Organization for Standardization (ISO), 1, ch. de
For referenced ASTM standards, visit the ASTM website, www.astm.org, or la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM www.iso.ch.
Standards volume information, refer to the standard’s Document Summary page on Available from Gas Processors Association (GPA), 66 American Plaza, Suite
the ASTM website. 700, Tulsa, OK 74135, http://www.gpaglobal.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7164 − 21
4. Summary of Practice 6.3 Sample Inlet System—The siting and installation of an
at-line or on-line monitor is critical for collecting representa-
4.1 Arepresentative sample of the gaseous fuel is extracted
tive information on heating value content. Factors that should
from a process pipe or a pipeline and is transferred in a timely
be considered in siting an instrument include ease of
manner to an analyzer sampling system. After appropriate
calibration, ease of access for repair or maintenance, sample
conditioning steps that maintain the sample’s integrity are
uniformity at the sampling point, appropriateness of samples
completed, a precise volume of sample is injected onto an
from a sampling location, ambient conditions, and of course
appropriate gas chromatographic column. Excess extracted
safety issues. An automated gas sampling valve is required in
process or pipeline sample is vented to atmosphere, a flare
many applications.All sampling system components in contact
header, or is returned to the process in accordance with
with the fuel stream must be constructed of inert or passivated
applicable economic and environmental requirements and
materials. Care must be taken to ensure that the extracted
regulations.
sample is maintained in the gaseous phase throughout pressure
4.2 Sample constituents are separated in the column to elute
reduction and transport throughout the expected ranges of
individuallyforidentificationandquantificationbythedetector
ambient and pipeline temperatures and pressure. The addition
and its data handling system. Heating value is calculated using
of heat at the point of pressure reduction and along the sample
the results of the compositional analysis and the calculations
line to the analyzer may be required to ensure that the entire
contained in Practice D3588 or other standard algorithms.
sample is maintained in the gas phase during all expected
operating conditions and gas compositions. When selecting
4.3 Calibration, maintenance, and performance protocols
sample conditioning equipment, equations of state should be
provide a means to validate the analyzer operation.
used to determine whether pressure must be reduced in
multiple stages to prevent a change of phase.The need for heat
5. Significance and Use
tracing and the extent to which it is required will be site
5.1 On-line, at-line, in-line, and other near-real time moni-
specific. In general, considerations impacting heat tracing
toring systems that measure fuel gas characteristics such as the
decisions include sample compositions and the expected
heating value are prevalent in the natural gas and fuel gas
variations, ambient temperature fluctuations, operating
industries. The installation and operation of particular systems
pressures, and anticipated pressure differentials in sample
vary on the specific objectives, process type, regulatory
system components. Sample filtration should be utilized as
requirements, and internal performance requirements needed
required to remove particulate matter from the extracted
by the user. This protocol is intended to provide guidelines for
sample and to prevent any contaminating liquids such as
standardized start-up procedures, operating procedures, and
glycol, compressor oils, and liquid water, which may form in
quality assurance practices for on-line, at-line, in-line, and
the event of heat-tracing failure, from reaching the chromato-
other near-real time heating value monitoring systems.
graph. The sampling frequency relative to the process band-
width is critical to ensuring that the reported analytical results
6. Apparatus
adequately represent the process being monitored. The
6.1 Instrument—Any instrument of standard manufacture, Nyquist-Shannon sampling criterion of a sampling frequency
with hardware necessary for interfacing to a natural gas or
that exceeds twice the process bandwidth can be used to
otherfuelgaspipelineandcontainingallthefeaturesnecessary establish a minimum analytical cycle time. Sample handling
for the intended application(s), can be used.
and conditioning system practices can be found in Practice
D5503.
6.1.1 Chromatographic-based Systems—The chromato-
graphic parameters employed generally should be capable of
6.3.1 Carrier and Detector Gas Control—Constant flow
obtaining a relative retention time repeatability of 0.05 min (3
carrier and detector gas control is critical for optimum and
s) for duplicate measurements. Instrumentation should satisfy
consistent analytical performance. Control is achieved by use
or exceed other chromatographic and analytic performance
of pressure regulators, mass flow controllers, and fixed flow
characteristics for accuracy and precision for the intended
restrictors. Temperature control is generally vital for ensuring
application without encountering unacceptable interference or
consistentoperationofthesedevices.Thegasflowismeasured
bias. In addition, components in contact with sample streams
by appropriate means and adjusted as necessary. Most chro-
suchastubingandvalvingmustbeconstructedofsuitableinert
matographs automatically control their gas flow rates which
materials to ensure constituents in the fuel stream do not
reduces a user’s responsibility for ensuring the proper gas
degrade these components or alter the composition of the
pressure is provided to the chromatograph. Should a chromato-
sampled gas. Additional information related to analyzing
graph require external gas flow control, mass flow controllers,
gaseous fuels using gas chromatography can be found in Test
capable of maintaining gas flow constant to 61 % at the flow
Method D1945, Practice D1946, and Test Method D7833.
rates necessary for optimal instrument performance, are gen-
erally used.
6.2 Sample Probes/Sample Extraction—The location and
orientation of sampling components are critical for ensuring 6.3.2 Detectors—A thermal conductivity detector (TCD) is
commonly used. Other detectors, such as the flame ionization
that a representative sample is analyzed. The locations and
orientation of sampling components should be selected based detector (FID), Practice E594, can be used but should at least
upon sound analytic and engineering considerations. Sampling meet TCD linearity, sensitivity, and selectivity in the selected
practices for gaseous fuels can be found in Practice D5287. application.
D7164 − 21
6.4 Columns—A variety of columns, ranging from packed 8. Equipment Siting and Installation
columns to open tubular capillary columns, can be used in the
8.1 A sampling (extraction, conditioning, and transport)
determination of the heating value of a gaseous fuel. Packed
system capable of operating continuously above the natural
columns and open tubular capillary columns are covered in
gas’ maximum dew point temperature is necessary. The loca-
Practices E260 and E1510 respectively. Columns should be
tion of the chromatograph relative to the sample extraction
conditioned in accordance with the manufacturer’s recommen-
point, and the internal volume of the sample conditioning and
dations. The selected column must provide retention and
transport system, are critical to obtaining timely analytical
resolution characteristics that satisfy the intended application.
results. Ideally, the chromatograph is installed close to the
The column must be inert and non-absorptive towards gaseous
sample extraction point and sample conditioning system using
fuel components. If the selected column utilizes a liquid phase,
the smallest diameter tubing recommended by the manufac-
bleeding at high temperatures must be sufficiently low to avoid
turer resulting in an insignificant sampling lag time. However,
the loss of instrument response during high temperature
it is common that the chromatograph is mounted at some
operation.
distance away from the sample extraction point.This increased
6.5 Data Acquisition—Data acquisition and storage can be
distance represents increased lag time between when a sample
accomplished using a number of devices and media. Following
is extracted from a process and when an analytical result is
are some examples.
reported. The maximum allowable lag time depends on the
6.5.1 Recorder—A0to1mVrangerecordingpotentiometer
specifics of the sampling location relative to the process being
or equivalent, with a full-scale response time of2sor less, can
sampled. Lag time can be minimized by reducing the pressure
be used.
of the sampled gas at, or near, the sample extraction point. In
6.5.2 Integrator—An electronic integrating device or com- addition, a bypass loop can be used to further reduce the lag
puter can be used. It is suggested that the device and software
time by increasing the volume, and therefore velocity, of the
have the following capabilities: sample being transported from the extraction point to the
6.5.2.1 Graphic presentation of chromatograms. chromatograph.The bypassed gas flow is either returned to the
process or vented in a safe manner.
6.5.2.2 Digital display of chromatographic peak areas.
6.5.2.3 Identification of peaks by retention time or relative
8.2 The sample should flow continuously without impedi-
retention time, or both.
ment through the sampling system. The sampling system
6.5.2.4 Calculation and use of response factors.
should be capable of delivering a representative sample to the
6.5.2.5 External standard calculation and data presentation.
chromatograp
...

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: D7164 − 10 (Reapproved 2015) D7164 − 21
Standard Practice for
On-line/At-line Heating Value Determination of Gaseous
Fuels by Gas Chromatography
This standard is issued under the fixed designation D7164; 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.
1. Scope
1.1 This practice is for the determination of heating value in high methane content gaseous fuels such as natural gas using an
on-line/at-line gas chromatograph.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3 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.
1.4 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:
D1070 Test Methods for Relative Density of Gaseous Fuels
D1945 Test Method for Analysis of Natural Gas by Gas Chromatography
D1946 Practice for Analysis of Reformed Gas by Gas Chromatography
D3588 Practice for Calculating Heat Value, Compressibility Factor, and Relative Density of Gaseous Fuels
D3764 Practice for Validation of the Performance of Process Stream Analyzer Systems
D4150 Terminology Relating to Gaseous Fuels
D4626 Practice for Calculation of Gas Chromatographic Response Factors
D5287 Practice for Automatic Sampling of Gaseous Fuels
D5503 Practice for Natural Gas Sample-Handling and Conditioning Systems for Pipeline Instrumentation (Withdrawn 2017)
D6122 Practice for Validation of the Performance of Multivariate Online, At-Line, Field and Laboratory Infrared
Spectrophotometer, and Raman Spectrometer Based Analyzer Systems
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6621 Practice for Performance Testing of Process Analyzers for Aromatic Hydrocarbon Materials
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-Line Analysis
of Gaseous Fuels.
Current edition approved Nov. 1, 2015April 1, 2021. Published December 2015May 2021. Originally approved in 2005. Last previous edition approved in 20102015 as
D7164D7164 – 10–10.(2015). DOI: 10.1520/D7164-15.10.1520/D7164-21.
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.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7164 − 21
D7833 Test Method for Determination of Hydrocarbons and Non-Hydrocarbon Gases in Gaseous Mixtures by Gas
Chromatography
E260 Practice for Packed Column Gas Chromatography
E594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
E1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs
2.2 ISO Standards
ISO 6976 Natural Gas — Calculation of Calorific Values, Density, Relative Density and Wobbe Indices From Composition
ISO 7504 Gas Analysis-Vocabulary
2.3 Gas Processors Association Standards:
GPA 2172 Calculation of Gross Heating Value, Relative Density, Compressibility and Theoretical Hydrocarbon Liquid Content
for Natural Gas Mixtures for Custody Transfer
3. Terminology
3.1 Definitions:
3.1.1 calibration gas mixture, n—a certified gas mixture with known composition used for the calibration of a measuring
instrument or for the validation of a measurement or gas analytical method.
3.1.1.1 Discussion—
Calibration Gas Mixtures are the analogues of measurement standards in physical metrology (reference ISO 7504 paragraph 4.1).
3.1.2 direct sampling—sampling where there is no direct connection between the medium to be sampled and the analytical unit.
3.1.3 in-line instrument—instrument with an active element installed in a pipeline, which is used to measure pipeline contents or
conditions.
3.1.4 on-line instrument—instrument that samples gas directly from a pipeline, but is installed externally.
3.1.5 at-line instrument—instrumentation requiring operator interaction that samples gas directly from the pipeline.
3.1.6 continuous fuel monitor—instrument that samples gas directly from the pipeline on a continuous or semi-continuous basis.
3.1.7 heating value—in general terms, the heating value is the total energy per volume transferred as heat from the complete, ideal
combustion of the gas at a specified temperature and pressure. The heating value can be reported on a net or gross basis for a
gaseous stream that is assumed to be fully water vapor saturated.
3.1.8 gross heating value—(also called higher heating value)—the amount of energy per volume transferred as heat from the
complete, ideal combustion of the gas at standard temperature in which all the water formed by the reaction condenses to liquid.
3.1.9 net heating value—(also called lower heating value)—the amount of energy per volume transferred as heat from the
complete, ideal combustion of the gas at standard temperature in which all the water formed by the reaction remains in the vapor
state.
3.1 For definitions of general terms used in D03 Gaseous Fuels standards, refer to Terminology D4150.
3.2 reference gas mixture, n—a certified gas mixture with known composition used as a reference standard from which other
compositional data are derived.
3.2.1 Discussion—
Reference Gas Mixtures are the analogues of measurement standards of reference standards (reference ISO 7504 paragraph 4.1.1).
4. Summary of Practice
4.1 A representative sample of the Gaseous Fuelgaseous fuel is extracted from a process pipe or a pipeline and is transferred in
Available from International Organization for Standardization (ISO), 1, ch. de la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://www.iso.ch.
Available from Gas Processors Association (GPA), 66 American Plaza, Suite 700, Tulsa, OK 74135, http://www.gpaglobal.org.
D7164 − 21
a timely manner to an analyzer sampling system. After appropriate conditioning steps that maintain the samplesample’s integrity
are completed, a precise volume of sample is injected onto an appropriate gas chromatographic column. Excess extracted process
or pipeline sample is vented to atmosphere, a flare header, or is returned to the process in accordance with applicable economic
and environmental requirements and regulations.
4.2 Sample constituents are separated in the column to elute individually for identification and quantification by the detector and
its data handling system. The heating Heating value is calculated using the results of the compositional analysis using an
appropriate algorithm.and the calculations contained in Practice D3588 or other standard algorithms.
4.3 Calibration, maintenance, and performance protocols provide a means to validate the analyzer operation.
5. Significance and Use
5.1 On-line, at-line, in-linein-line, and other near-real time monitoring systems that measure fuel gas characteristics such as the
heating value are prevalent in the natural gas and fuel gas industries. The installation and operation of particular systems vary on
the specific objectives, process type, regulatory requirements, and internal performance requirements needed by the user. This
protocol is intended to provide guidelines for standardized start-up procedures, operating procedures, and quality assurance
practices for on-line, at-line, in-linein-line, and other near-real time heating value monitoring systems.
6. Apparatus
6.1 Instrument—Any instrument of standard manufacture, with hardware necessary for interfacing to a natural gas or other fuel
gas pipeline and containing all the features necessary for the intended application(s)application(s), can be used.
6.1.1 Chromatographic-based Systems—The chromatographic parameters employed generally should be capable of obtaining a
relative retention time repeatability of 0.05 min (3 s) for duplicate measurements. Instrumentation should satisfy or exceed other
chromatographic and analytic performance characteristics for accuracy and precision for the intended application without
encountering unacceptable interference or bias. In addition, components in contact with sample streams such as tubing and valving
must be constructed of suitable inert materials to ensure constituents in the fuel stream do not degrade these components or alter
the composition of the sampled gas. Additional information related to analyzing gaseous fuels using gas chromatography can be
found in Test Method D1945 and , Practice D1946, and Test Method D7833.
6.2 Sample Probes/Sample Extraction—The location and orientation of sampling components are critical for ensuring that a
representative sample is analyzed. The locations and orientation of sampling components should be selected based upon sound
analytic and engineering considerations. Sampling practices for gaseous fuels can be found in Practice D5287.
6.3 Sample Inlet System—The siting and installation of an at-line or on-line monitor is critical for collecting representative
information on heating value content. Factors that should be considered in siting an instrument include ease of calibration, ease
of access for repair or maintenance, sample uniformity at the sampling point, appropriateness of samples from a sampling location,
ambient conditions, and of course safety issues. An automated gas sampling valve is required in many applications. All sampling
system components in contact with the fuel stream must be constructed of inert or passivated materials. Care shouldmust be taken
to ensure that the extracted sample is maintained in a single clean gaseous phase. the gaseous phase throughout pressure reduction
and transport throughout the expected ranges of ambient and pipeline temperatures and pressure. The addition of heat at the point
of pressure reduction orand along the sample line to the analyzer may be required to ensure that the entire sample is maintained
in the gas phase during all expected operating conditions and gas compositions. When selecting sample conditioning equipment,
equations of state should be used to determine whether pressure must be reduced in multiple stages to prevent a change of phase.
The need for heat tracing and the extent to which it is required will be site specific. In general, considerations impacting heat
tracing decisions include sample compositions and the expected variations, ambient temperature fluctuations, operating pressures,
and anticipated pressure differentials in sample system components. Sample filtration should be utilized as required to remove
particulate matter from the extracted sample. sample and to prevent any contaminating liquids such as glycol, compressor oils, and
liquid water, which may form in the event of heat-tracing failure, from reaching the chromatograph. The sampling frequency
relative to the process bandwidth is critical to ensuring that the reported analytical results adequately represent the process being
monitored. The Nyquist-Shannon sampling criterion of a sampling frequency that exceeds twice the process bandwidth can be used
to establish a minimum analytical cycle time. Sample handling and conditioning system practices can be found in Practice D5503.
6.3.1 Carrier and Detector Gas Control—Constant flow control of carrier and detector gases gas control is critical for optimum
and consistent analytical performance. Control is achieved by use of pressure regulators regulators, mass flow controllers, and fixed
D7164 − 21
flow restrictors. Temperature control is generally vital for ensuring consistent operation of these devices. The gas flow is measured
by appropriate means and adjusted as necessary. Mass flow Most chromatographs automatically control their gas flow rates which
reduces a user’s responsibility for ensuring the proper gas pressure is provided to the chromatograph. Should a chromatograph
require external gas flow control, mass flow controllers, capable of maintaining gas flow constant to 61 % at the flow rates
necessary for optimal instrument performance, are generally used.
6.3.2 Detectors—A thermal conductivity detector (TCD) is commonly used. Other detectors, such as the flame ionization detector
(FID), Practice E594, can be used but should at least meet TCD linearity, sensitivity, and selectivity in the selected application.
6.4 Columns—A variety of columns, ranging from packed columns to open tubular capillary columns, can be used in the
determination of the Heating Valueheating value of a gaseous fuel. Packed columns and open tubular capillary columns are covered
in Practices E260 and E1510 respectively. Columns should be conditioned in accordance with the manufacturer’s recommenda-
tions. The selected column must provide retention and resolution characteristics that satisfy the intended application. The column
must be inert and non-absorptive towards gaseous fuel components. If the selected column utilizes a liquid phase, bleeding at high
temperatures must be sufficiently low so as to avoid the loss of instrument response during high temperature operation.
6.5 Data Acquisition—Data acquisition and storage can be accomplished using a number of devices and media. Following are
some examples.
6.5.1 Recorder—A 0 to 1 mV range recording potentiometer or equivalent, with a full-scale response time of 2 s or less, can be
used.
6.5.2 Integrator—An electronic integrating device or computer can be used. For GC-based systems, it It is suggested that the
device and software have the following capabilities:
6.5.2.1 Graphic presentation of chromatograms.
6.5.2.2 Digital display of chromatographic peak areas.
6.5.2.3 Identification of peaks by retention time or relative retention time, or both.
6.5.2.4 Calculation and use of response factors.
6.5.2.5 External standard calculation and data presentation.
6.5.2.6 Site-appropriate archives up to one month of all runs. Archives could include raw data, derived component values or
heating value results or both. Hourly, daily, and monthly averages are included as required.
6.5.3 Communications Systems—Efficient communications between the analyzer and the host depend on resolving any and all
interface issues. Signals to and from the host are typically optically isolated from each other.
7. Reagents and Materials
NOTE 1—Warning: Compressed gas standards should only be handled in well ventilated locations away from sparks and flames. Improper handling of
compressed gas cylinders containing calibration standards, air, nitrogen, hydrogen, argon, or helium can result in explosion. Rapid release of nitrogen
or helium can result in asphyxiation. Compressed air supports combustion.
7.1 Standards—The components inwithin the reference stan
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