ASTM D7314-21

Standard Practice for Determination of the Heating Value of Gaseous Fuels using Calorimetry and On-line/At-line Sampling

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 heating value, are prevalent in various gaseous fuel industries and in industries either producing or using gaseous fuel in their industrial processes. The installation and operation of particular systems vary depending on process type, regulatory requirements, and the user’s objectives and performance requirements. This practice is intended to provide guidance for standardized start-up procedures, operating procedures, and quality assurance practices for calorimeter based on-line, at-line, in-line, and other near-real time heating value monitoring systems. Users employing gas chromatographic based instrumentation for measurement of gaseous fuel heating value are referred to Practice D7164.
SCOPE
1.1 This practice is for the determination of the heating value measurement of gaseous fuels using a calorimeter. Heating value determination of sample gasses containing water vapor will require vapor phase moisture measurements of the pre-combustion sample gas as well as the non-condensed gasses exiting the calorimeter. Instruments equipped with appropriate conditioners and algorithms may provide heating value results on a net or gross and dry or wet basis.  
1.2 This practice is applicable to at-line and in-line instruments that are operated from time to time on a continuous basis.  
1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
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-Mar-2021
• ICS: 17.200.10 - Heat. Calorimetry
• 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 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 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 D1826-94(2017) - Standard Test Method for Calorific (Heating) Value of Gases in Natural Gas Range by Continuous Recording Calorimeter
• Effective Date: 01-Apr-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
• Refers: ASTM D5287-08(2015) - Standard Practice for Automatic Sampling of Gaseous Fuels (Withdrawn 2024)
• Effective Date: 01-Jun-2015
• 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 D7314-21 establishes a standardized practice for the determination of the heating value of gaseous fuels using calorimetry, with a focus on on-line, at-line, in-line, and near-real-time sampling systems. This standard is widely adopted by industries that produce, process, or utilize gaseous fuels, ensuring consistent and accurate measurement vital for process control, energy management, product quality, and regulatory compliance.

Heating value measurement is fundamental to assessing the energy content in gaseous fuels such as natural gas and other industrial gases. ASTM D7314-21 provides clear guidelines on the start-up, operation, calibration, and maintenance of calorimeter-based analytical systems, supporting quality assurance and consistent reporting practices across the energy and industrial sectors.

Key Topics

• Calorimetric Measurement of Heating Value: The practice outlines procedures using calorimeters to determine the energy content of gaseous fuels. It covers both net and gross basis, as well as dry or wet gas conditions, depending on moisture measurements.

• Sampling Systems: Recommendations for sampling methods, including direct, at-line, on-line, and in-line sampling arrangements. The correct selection and operation of probes, sample extraction systems, and sample conditioning are emphasized to ensure representativity and integrity.

• System Calibration and Quality Assurance: ASTMD7314-21 details protocols for calibration using certified calibration gas mixtures and reference gas mixtures, system blank tests, drift checks, and validation against laboratory standards to maintain analytical accuracy.

• Performance and Maintenance: The standard provides maintenance guidance, including regular inspection, cleaning, and recalibration, to uphold measurement reliability. It also recommends performance tests such as audit tests, linearity checks, and comparison with laboratory results.

• Data Acquisition and Reporting: Outlines best practices for recording, storing, and communicating measurement data, ensuring timely and accurate reporting of heating values for process decision-making.

• Safety and Compliance: Users are reminded to establish safety, health, and environmental practices aligned with regulations, as the handling of gases and pressurized systems presents inherent risks.

Applications

ASTM D7314-21 is applicable across a wide range of industries and scenarios, including:

• Natural Gas and Pipeline Monitoring: Provides accurate and real-time heating value data for custody transfer, billing, and regulatory reporting.
• Refineries and Petrochemical Plants: Used for monitoring fuel gas streams to optimize combustion, improve efficiency, and maintain emissions compliance.
• Power Generation: Ensures gas-fired power plants receive fuel of a consistent quality, supporting optimal turbine performance and emissions control.
• Process Industries: Supports monitoring and control of fuel gas streams in chemical, manufacturing, and industrial operations.
• Quality Control and Compliance: Essential for operations required to demonstrate conformity with contractual, industry, and regulatory requirements for energy content.

Related Standards

ASTM D7314-21 interfaces with several other key standards for gaseous fuels and process analysis:

• ASTM D1070: Relative Density of Gaseous Fuels
• ASTM D1826: Calorific (Heating) Value of Gases in the Natural Gas Range by Continuous Recording Calorimeter
• 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 D4891: Heating Value of Gases in Natural Gas and Flare Gases Range by Stoichiometric Combustion
• ASTM D5287: Automatic Sampling of Gaseous Fuels
• ASTM D6122: Validation of Performance of Multivariate Online, At-Line, and Laboratory Analyzer Systems
• ASTM D6299: Statistical Quality Assurance Techniques
• ASTM D6621: Performance Testing of Process Analyzers for Aromatic Hydrocarbons
• ASTM D7164: On-line/At-line Heating Value Determination of Gaseous Fuels by Gas Chromatography

By referencing and following ASTM D7314-21, organizations ensure reliable, safe, and consistent heating value determination of gaseous fuels, crucial for process optimization, regulatory compliance, and operational excellence.

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: D7314 − 21
Standard Practice for
Determination of the Heating Value of Gaseous Fuels using
Calorimetry and On-line/At-line Sampling
This standard is issued under the fixed designation D7314; 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 D3588 Practice for Calculating Heat Value, Compressibility
Factor, and Relative Density of Gaseous Fuels
1.1 This practice is for the determination of the heating
D3764 Practice forValidation of the Performance of Process
value measurement of gaseous fuels using a calorimeter.
Stream Analyzer Systems
Heatingvaluedeterminationofsamplegassescontainingwater
D4150 Terminology Relating to Gaseous Fuels
vapor will require vapor phase moisture measurements of the
D4891 Test Method for Heating Value of Gases in Natural
pre-combustion sample gas as well as the non-condensed
Gas and Flare Gases Range by Stoichiometric Combus-
gasses exiting the calorimeter. Instruments equipped with
tion
appropriate conditioners and algorithms may provide heating
D5287 Practice for Automatic Sampling of Gaseous Fuels
value results on a net or gross and dry or wet basis.
D5503 Practice for Natural Gas Sample-Handling and Con-
1.2 This practice is applicable to at-line and in-line instru-
ditioning Systems for Pipeline Instrumentation (With-
ments that are operated from time to time on a continuous
drawn 2017)
basis.
D6122 Practice for Validation of the Performance of Multi-
variate Online, At-Line, Field and Laboratory Infrared
1.3 Units—The values stated in SI units are to be regarded
as standard. No other units of measurement are included in this Spectrophotometer, and Raman Spectrometer Based Ana-
lyzer Systems
standard.
D6299 Practice for Applying Statistical Quality Assurance
1.4 This standard does not purport to address all of the
and Control Charting Techniques to Evaluate Analytical
safety concerns, if any, associated with its use. It is the
Measurement System Performance
responsibility of the user of this standard to establish appro-
D6621 Practice for Performance Testing of Process Analyz-
priate safety, health, and environmental practices and deter-
ers for Aromatic Hydrocarbon Materials
mine the applicability of regulatory limitations prior to use.
D7164 Practice for On-line/At-line Heating Value Determi-
1.5 This international standard was developed in accor-
nation of Gaseous Fuels by Gas Chromatography
dance with internationally recognized principles on standard-
2.2 ISO Standards:
ization established in the Decision on Principles for the
ISO 14532 Natural Gas—Vocabulary
Development of International Standards, Guides and Recom-
ISO 7504 Gas Analysis—Vocabulary
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
3. Terminology
2. Referenced Documents 3.1 Refer to Terminology D4150 for general definitions
2 related to gaseous fuels. Definitions specific to this standard
2.1 ASTM Standards:
follow.
D1070 Test Methods for Relative Density of Gaseous Fuels
D1826 TestMethodforCalorific(Heating)ValueofGasesin 3.2 Definitions of Terms Specific to This Standard:
Natural Gas Range by Continuous Recording Calorimeter 3.2.1 auto-verification, n—an automated means of introduc-
ing calibration gas mixtures or reference gas mixtures into an
analyzer for the purposes of verifying the analyzer response
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous
without making any adjustments to the calibration parameters
Fuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-Line
Analysis of Gaseous Fuels. of the analyzer.
Current edition approved April 1, 2021. Published May 2021. Originally
approved in 2008. Last previous edition approved in 2015 as D7314 – 10(2015).
DOI: 10.1520/D7314-21. The last approved version of this historical standard is referenced on
For referenced ASTM standards, visit the ASTM website, www.astm.org, or www.astm.org.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Available from International Organization for Standardization (ISO), 1, ch. de
Standards volume information, refer to the standard’s Document Summary page on la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://
the ASTM website. www.iso.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7314 − 21
3.2.2 bypass line, n—line ultimately vented to the atmo- 6. Apparatus
spherethatisusedwhereitisimpracticaltoprovideasufficient
6.1 Instrument—Any instrument of standard manufacture,
pressure differential.
with hardware necessary for interfacing to a fuel gas pipeline
3.2.2.1 Discussion—Flowrate—The flowrate and pressure
and containing all the features necessary for the intended
loss in the open-ended line needs to be controlled so as to
application(s), can be used.
ensure that the sample accuracy is not affected from any
6.1.1 Combustion System—Operating parameters employed
cooling and condensation, or both (reference ISO 14532,
must be capable of converting all of the volatile combustible
paragraph 2.3.2.9).
chemical species in the sample into carbon dioxide, water,
3.2.2.2 Discussion—Loop—The loop requires a pressure
nitrogen, nitrogen dioxide, or sulfur dioxide, or a combination
differential from the collection point to the discharge point so
thereof, using a dry, hydrocarbon-free oxidant, which is typi-
as to ensure a constant and steady flowrate through the
cally air.Achange of less than or equal to 1000 ppm/wt in the
sampling equipment located in the loop (reference ISO 14532,
moisture content of instrument air between calorimeter cali-
paragraph, 2.3.2.8).
brations is acceptable to maintain a statistically insignificant
3.2.2.3 Discussion—Reference Gas—Reference gas mix-
60.1 % heating value accuracy as denoted in Practice D4891.
tures are the analogues of reference standards (ISO 7504,
The less than 1000 ppm/wt moisture content control value is
paragraph 4.1.1).
easily achieved using desiccant or refrigerant air dryers when
the air dryers are maintained according to the manufacturer’s
3.2.3 fast loop/hot loop, n—bypass loop that returns
recommendations. Instrumentation must satisfy or exceed ana-
sampled gas to the process line in a closed configuration and
lyticperformancecharacteristicsforaccuracyandprecisionfor
used for environmental and safety considerations.
the intended application without encountering unacceptable
3.3 Acronyms:
interference or bias. In addition, components in contact with
3.3.1 SOP, n—Standard Operating Procedure.
samplestreamssuchastubingandvalvingmustbeconstructed
3.3.2 QA, n—Quality Assurance.
of suitable inert or passivated materials to ensure that the
composition of the sampled gas is not altered.
4. Summary of Practice
6.2 Sample Probes/Sample Extraction—The location and
4.1 Arepresentative sample of the gaseous fuel is extracted orientation of sampling components are critical for ensuring
from a process pipe, a pipeline, or other gaseous fuel stream, that a representative sample is analyzed. The locations and
and is transferred to an analyzer sampling system. After
orientation of sampling components should be selected based
conditioning that maintains the sample integrity, the sample is upon sound analytic and engineering considerations. Sampling
introduced into a calorimeter. Excess extracted process or
practices for gaseous fuels can be found in Practice D5287.
sample gas is vented to the atmosphere, a flare header, or is
6.3 Sample Inlet System—An automated gas sampling valve
returnedtotheprocessinaccordancewithapplicableeconomic
is required in many applications. All sampling system compo-
and environmental requirements and regulations. Post-
nents in contact with the fuel stream must be constructed of
combustion gasses from the calorimeter are typically vented to
inert or passivated materials. Care should be taken to ensure
the atmosphere.
that the extracted sample is maintained in a single clean
gaseous phase. The addition of heat at the point of pressure
4.2 The heating value is calculated based upon the instru-
reduction or along the sample line to the analyzer may be
ment’s response to changes in the heating value of the sample
required to ensure that the sample is maintained in the gas
gas using an algorithm.
phase. The need for heat tracing and the extent to which it is
4.3 Calibration (7.1), maintenance (Section 10), and perfor-
required will be site specific. In general, considerations im-
mance (Section 9) protocols provide a means to validate and
pactingheattracingdecisionsincludesamplecompositionsand
assess operation of the analyzer.
the expected variations, ambient temperature fluctuations,
operating pressures, and anticipated pressure differentials in
5. Significance and Use
sample system components. Sample filtration should be uti-
5.1 On-line, at-line, in-line, and other near-real time moni- lized as required to remove particulate matter from the ex-
toring systems that measure fuel gas characteristics, such as tracted sample.
heating value, are prevalent in various gaseous fuel industries 6.3.1 Combustion Air, Sample, and Carrier Gas Control—
and in industries either producing or using gaseous fuel in their Constant flow control of combustion air, sample gas, and
industrial processes. The installation and operation of particu- carrier gas, if required by the measurement application, is
lar systems vary depending on process type, regulatory necessary for optimum and consistent analytical performance.
requirements, and the user’s objectives and performance re- Control is typically achieved by use of pressure regulators and
quirements. This practice is intended to provide guidance for fixed flow restrictors. Ambient, combustion air, sample, and
standardized start-up procedures, operating procedures, and carrier gas temperature control is generally vital for ensuring
quality assurance practices for calorimeter based on-line, consistent operation of flow control devices. The gas flow is
at-line, in-line, and other near-real time heating value monitor- measured and verified by appropriate means and adjusted as
ing systems. Users employing gas chromatographic based necessary.
instrumentation for measurement of gaseous fuel heating value 6.3.2 Detectors—Common calorimetry heating value detec-
are referred to Practice D7164. tion systems include stoichiometric combustion (Test Method
D7314 − 21
D4891), continuous recording calorimeters (Test Method safety issues. A sample inlet system capable of operating
D1826), non-stoichiometric combustion, and residual oxygen continuously at or above the maximum operating sample
detection calorimeters. Other detectors can be used provided temperatureisnecessary.Thelocationofthesampleinlettothe
they have appropriate linearity, accuracy, sensitivity, and mea- analyzer relative to the sample extraction point is critical to
surement range for the selected application. In selecting a obtaining timely analytical results. Ideally, the analyzer is
detector, the user should consider the linearity and sensitivity close-coupled to the sample extraction point and there is an
of a particular detection system prior to installation. The user insignificant sampling lag time. Normally, the analyzer is
should also consider potential sample compositional effects mounted at some distance away from the sample extraction
that may influence the reported heating value. point. This increased distance will result in increased lag time
between when a sample is extracted from a process and when
6.4 Data Acquisition—Data acquisition and storage can be
an analytical result is reported. The maximum allowable lag
accomplished using a number of devices and media. Following
time depends on the specifics of the sampling location relative
are some examples:
totheprocessbeingsampled.Afastlooporby-passlinecanbe
6.4.1 Recorder—A0 to 1 millivolt or a 4-20 milliamp range
usedtominimizethelagtime.Thesamplingfrequencyrelative
recording potentiometer or equivalent, with a full-scale re-
totheprocessbandwidthiscriticaltoensuringthatthereported
sponse time of 2 s or less can be used mounted locally or
analytical results adequately represent the process being moni-
remotely.
tored. The Nyquist-Shannon sampling criterion of a sampling
6.4.2 Communications Systems—Efficient communications
frequency that exceeds twice the process bandwidth can be
between the analyzer and the host depend on resolving any and
used to establish a minimum analytical cycle time. Sample
all interface issues. Signals to and from the host are typically
handling and conditioning system practices can be found in
isolated from each other in an appropriate manner.
Practice D5503.
7. Reagents and Materials
8.2 The sample should flow continuously through the in-
strument samplin
...

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: D7314 − 10 (Reapproved 2015) D7314 − 21
Standard Practice for
Determination of the Heating Value of Gaseous Fuels using
Calorimetry and On-line/At-line Sampling
This standard is issued under the fixed designation D7314; 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 the heating value measurement of gaseous fuels using a calorimeter. Heating value
determination of sample gasses containing water vapor will require vapor phase moisture measurements of the pre-combustion
sample gas as well as the non-condensed gasses exiting the calorimeter. Instruments equipped with appropriate conditioners and
algorithms may provide heating value results on a net or gross and dry or wet basis.
1.2 This practice is applicable to at-line and in-line instruments that are operated from time to time on a continuous basis.
1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
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 and health practices and determine the applicability of regulatory
limitations prior to use.
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:
D1070 Test Methods for Relative Density of Gaseous Fuels
D1826 Test Method for Calorific (Heating) Value of Gases in Natural Gas Range by Continuous Recording Calorimeter
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
D4891 Test Method for Heating Value of Gases in Natural Gas and Flare Gases Range by Stoichiometric Combustion
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 June 1, 2015April 1, 2021. Published July 2015May 2021. Originally approved in 2008. Last previous edition approved in 20102015 as
D7314D7314 – 10-10.(2015). DOI: 10.1520/D7314-10R15.10.1520/D7314-21.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7314 − 21
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
D7164 Practice for On-line/At-line Heating Value Determination of Gaseous Fuels by Gas Chromatography
2.2 ISO Standards:
ISO 14532 Natural gas—VocabularyGas—Vocabulary
ISO 7504 Gas analysis—VocabularyAnalysis—Vocabulary
3. Terminology
3.1 Refer to Terminology D4150 for general definitions related to gaseous fuels. Definitions specific to this standard follow.
3.2 Definitions:Definitions of Terms Specific to This Standard:
3.1.1 at-line instrument, n—See Terminology D4150, Section 3.
3.2.1 auto-verification, n—an automated means of introducing Calibration Gas Mixtures or Reference Gas Mixturescalibration gas
mixtures or reference gas mixtures into an analyzer for the purposes of verifying the analyzer response without making any
adjustments to the calibration parameters of the analyzer.
3.2.2 bypass line, n—Lineline ultimately vented to the atmosphere that is used where it is impractical to provide a sufficient
pressure differential.
3.2.2.1 Discussion—
TheFlowrate—The flowrate and pressure loss in the open-ended line needs to be controlled so as to ensure that the sample accuracy
is not affected from any cooling and condensation, or both (reference ISO 14532, paragraph 2.3.2.9).
3.2.2.2 Discussion—
Loop—The loop requires a pressure differential from the collection point to the discharge point so as to ensure a constant and
steady flowrate through the sampling equipment located in the loop (reference ISO 14532, paragraph, 2.3.2.8).
3.2.2.3 Discussion—
Reference Gas—Reference gas mixtures are the analogues of reference standards (ISO 7504, paragraph 4.1.1).
3.1.4 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.
3.1.4.1 Discussion—
Calibration Gas Mixtures are the analogues of measurement standards in physical metrology (reference ISO 7504 paragraph 4.1)
3.1.5 calorimeter, n—See Terminology D4150, Section 3.
3.1.6 continuous fuel monitor, n—an instrument that samples gas directly from a source continuously and provides an analytical
result on a continuous or semi-continuous basis.
3.1.7 direct sampling, adj—sampling where there is a direct connection between the sample source and the analytical unit, that
is, in-line or on-line instrument.
3.1.8 dry gas, n—See Terminology D4150, Section 3.
3.1.9 fast loop/hot loop, n—Bypass loop that returns sampled gas to the process line in a closed configuration and used for
environmental and safety considerations.
3.1.9.1 Discussion—
The last approved version of this historical standard is referenced on www.astm.org.
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.
D7314 − 21
The loop requires a pressure differential from the collection point to the discharge point so as to ensure a constant and steady
flowrate through the sampling equipment located in the loop (reference ISO 14532 paragraph 2.3.2.8)
3.1.10 gross heating value (also called higher heating value), n—See Terminology D4150, Section 3.
3.1.11 heating value, n—the amount of energy per volume transferred as heat from the complete, ideal combustion of the gas at
standard temperature.
3.1.12 in-line instrument, n—See Terminology D4150, Section 3.
3.1.13 net heating value (also called lower heating value), n—See Section 3 entitled Terminology, of D4150.
3.1.14 on-line instrument, n—See Terminology D4150, Section 3.
3.1.15 reference gas mixture, n—a certified gas mixture with known composition used as a reference standard from which other
compositional data are derived.
3.1.15.1 Discussion—
Reference Gas Mixtures are the analogues of reference standards (ISO 7504 paragraph 4.1.1)
3.2.3 wet gas, fast loop/hot loop, n—See Terminologybypass loop D4150, Section 3.that returns sampled gas to the process line
in a closed configuration and used for environmental and safety considerations.
3.3 Acronyms:
3.3.1 SOP, n—Standard Operating Procedure.
3.3.2 QA, n—Quality Assurance.
4. Summary of Practice
4.1 A representative sample of the gaseous fuel is extracted from a process pipe, a pipeline, or other gaseous fuel stream, and is
transferred to an analyzer sampling system. After conditioning that maintains the sample integrity, the sample is introduced into
a calorimeter. Excess extracted process or sample gas is vented to the atmosphere, a flare header, or is returned to the process in
accordance with applicable economic and environmental requirements and regulations. Post-combustion gasses from the
calorimeter are typically vented to the atmosphere.
4.2 The heating value is calculated based upon the instrument’s response to changes in the heating value of the sample gas using
an algorithm.
4.3 Calibration (7.1), maintenance (Section 10), and performance (Section 9) protocols provide a means to validate and assess
operation of the analyzer.
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
heating value, are prevalent in various gaseous fuel industries and in industries either producing or using gaseous fuel in their
industrial processes. The installation and operation of particular systems vary depending on process type, regulatory requirements,
and the user’s objectives and performance requirements. This practice is intended to provide guidance for standardized start-up
procedures, operating procedures, and quality assurance practices for calorimeter based on-line, at-line, in-linein-line, and other
near-real time heating value monitoring systems. Users employing gas chromatographic based instrumentation for measurement
of gaseous fuel heating value are referred to Practice D7164.
6. Apparatus
6.1 Instrument—Any instrument of standard manufacture, with hardware necessary for interfacing to a fuel gas pipeline and
containing all the features necessary for the intended application(s)application(s), can be used.
D7314 − 21
6.1.1 Combustion System—Operating parameters employed must be capable of converting all of the volatile combustible chemical
species in the sample into carbon dioxide, water, nitrogen, nitrogen dioxide, and/oror sulfur dioxide, or a combination thereof,
using a dry, hydrocarbon-free oxidant, which is typically air. A change of less than or equal to 1,0001000 ppm/wt in the moisture
content of instrument air between calorimeter calibrations is acceptable to maintain a statistically insignificant 6 0.1% 60.1 %
heating value accuracy as denoted in Practice D4891. The less than 1,0001000 ppm/wt moisture content control value is easily
achieved using desiccant or refrigerant air dryers when the air dryers are maintained according to the manufacturer’s
recommendations. Instrumentation must satisfy or exceed 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 or passivated materials to ensure that the composition of
the sampled gas is not altered.
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—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 should be taken to ensure that the
extracted sample is maintained in a single clean gaseous phase. The addition of heat at the point of pressure reduction or along
the sample line to the analyzer may be required to ensure that the sample is maintained in the gas 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.
6.3.1 Combustion Air, Sample, and Carrier Gas Control—Constant flow control of combustion air, sample gas, and carrier gas,
if required by the measurement application, is necessary for optimum and consistent analytical performance. Control is typically
achieved by use of pressure regulators and fixed flow restrictors. Ambient, combustion air, sample, and carrier gas temperature
control is generally vital for ensuring consistent operation of flow control devices. The gas flow is measured and verified by
appropriate means and adjusted as necessary.
6.3.2 Detectors—Common calorimetry heating value detection systems include stoichiometric combustion (Test Method D4891),
continuous recording calorimeters (Test Method D1826), non-stoichiometric combustion, and residual oxygen detection
calorimeters. Other detectors can be used provided they have appropriate linearity, accuracy, sensitivity, and measurement range
for the selected application. In selecting a detector, the user should consider the linearity and sensitivity of a particular detection
system prior to installation. The user should also consider potential sample compositional effects that may influence the reported
heating value.
6.4 Data Acquisition—Data acquisition and storage can be accomplished using a number of devices and media. Following are
some examples:
6.4.1 Recorder—A 0 to 1 millivolt or a 4-20 milliamp range recording potentiometer or equivalent, with a full-scale response time
of 2 s or less can be used mounted locally or remotely.
6.4.2 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 isolated from each other in an appropriate manner.
7. Reagents and Materials
7.1 Warning—Compressed gas standards should only be handled in well ventilated locations away from sparks and flames.
Improper handling of compressed gas cylinders containing
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