ASTM D7164-10(2015)
(Practice)Standard Practice for On-line/At-line Heating Value Determination of Gaseous Fuels by Gas Chromatography
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 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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Designation: D7164 − 10 (Reapproved 2015)
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 D6299 Practice for Applying Statistical Quality Assurance
and Control Charting Techniques to Evaluate Analytical
1.1 This practice is for the determination of heating value in
Measurement System Performance
high methane content gaseous fuels such as natural gas using
D6621 Practice for Performance Testing of Process Analyz-
an on-line/at-line gas chromatograph.
ers for Aromatic Hydrocarbon Materials
1.2 The values stated in SI units are to be regarded as
E260 Practice for Packed Column Gas Chromatography
standard. No other units of measurement are included in this
E594 Practice for Testing Flame Ionization Detectors Used
standard.
in Gas or Supercritical Fluid Chromatography
1.3 This standard does not purport to address all of the
E1510 Practice for Installing Fused Silica Open Tubular
safety concerns, if any, associated with its use. It is the Capillary Columns in Gas Chromatographs
responsibility of the user of this standard to establish appro-
2.2 ISO Standards
priate safety and health practices and determine the applica-
ISO 7504 Gas Analysis-Vocabulary
bility of regulatory limitations prior to use.
3. Terminology
2. Referenced Documents
3.1 Definitions:
2.1 ASTM Standards: 3.1.1 calibration gas mixture, n—a certified gas mixture
D1070 Test Methods for Relative Density of Gaseous Fuels
with known composition used for the calibration of a measur-
D1945 Test Method for Analysis of Natural Gas by Gas ing instrument or for the validation of a measurement or gas
Chromatography
analytical method.
D1946 Practice for Analysis of Reformed Gas by Gas 3.1.1.1 Discussion—Calibration Gas Mixtures are the ana-
Chromatography
logues of measurement standards in physical metrology (ref-
D3588 Practice for Calculating Heat Value, Compressibility
erence ISO 7504 paragraph 4.1).
Factor, and Relative Density of Gaseous Fuels
3.1.2 direct sampling—sampling where there is no direct
D3764 Practice forValidation of the Performance of Process
connection between the medium to be sampled and the
Stream Analyzer Systems
analytical unit.
D4626 Practice for Calculation of Gas Chromatographic
3.1.3 in-line instrument—instrument with an active element
Response Factors
installed in a pipeline, which is used to measure pipeline
D5287 Practice for Automatic Sampling of Gaseous Fuels
contents or conditions.
D5503 Practice for Natural Gas Sample-Handling and Con-
3.1.4 on-line instrument—instrument that samples gas di-
ditioning Systems for Pipeline Instrumentation
rectly from a pipeline, but is installed externally.
D6122 Practice for Validation of the Performance of Multi-
variate Online,At-Line, and Laboratory Infrared Spectro-
3.1.5 at-line instrument—instrumentationrequiringoperator
photometer Based Analyzer Systems
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
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous
basis.
Fuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-Line
Analysis of Gaseous Fuels.
3.1.7 heating value—in general terms, the heating value is
Current edition approved Nov. 1, 2015. Published December 2015. Originally
the total energy per volume transferred as heat from the
approved in 2005. Last previous edition approved in 2010 as D7164–10. DOI:
10.1520/D7164-15.
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 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
D7164 − 10 (2015)
complete, ideal combustion of the gas at a specified tempera- 6.1.1 Chromatographic-based Systems—The chromato-
ture and pressure. The heating value can be reported on a net graphic parameters employed generally should be capable of
or gross basis for a gaseous stream that is assumed to be fully
obtaining a relative retention time repeatability of 0.05 min (3
water vapor saturated. s) for duplicate measurements. Instrumentation should satisfy
or exceed other chromatographic and analytic performance
3.1.8 gross heating value—(also called higher heating
characteristics for accuracy and precision for the intended
value)—the amount of energy per volume transferred as heat
application without encountering unacceptable interference or
from the complete, ideal combustion of the gas at standard
bias. In addition, components in contact with sample streams
temperature in which all the water formed by the reaction
suchastubingandvalvingmustbeconstructedofsuitableinert
condenses to liquid.
materials to ensure constituents in the fuel stream do not
3.1.9 net heating value—(alsocalledlowerheatingvalue)—
degrade these components or alter the composition of the
the amount of energy per volume transferred as heat from the
sampled gas. Additional information related to analyzing
complete, ideal combustion of the gas at standard temperature
gaseous fuels using gas chromatography can be found in Test
in which all the water formed by the reaction remains in the
Method D1945 and Practice D1946.
vapor state.
3.2 reference gas mixture, n—a certified gas mixture with 6.2 Sample Probes/Sample Extraction—The location and
known composition used as a reference standard from which orientation of sampling components are critical for ensuring
other compositional data are derived. that a representative sample is analyzed. The locations and
3.2.1 Discussion—Reference Gas Mixtures are the ana-
orientation of sampling components should be selected based
logues of measurement standards of reference standards (ref- upon sound analytic and engineering considerations. Sampling
erence ISO 7504 paragraph 4.1.1).
practices for gaseous fuels can be found in Practice D5287.
6.3 Sample Inlet System—The siting and installation of an
4. Summary of Practice
at-line or on-line monitor is critical for collecting representa-
4.1 ArepresentativesampleoftheGaseousFuelisextracted
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 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 should be taken to ensure that the extracted
regulations.
sample is maintained in a single clean gaseous phase. The
4.2 Sample constituents are separated in the column to elute
addition of heat at the point of pressure reduction or along the
individuallyforidentificationandquantificationbythedetector
sample line to the analyzer may be required to ensure that the
and its data handling system. The heating value is calculated
sample is maintained in the gas phase. The need for heat
using the results of the compositional analysis using an
tracing and the extent to which it is required will be site
appropriate algorithm.
specific. In general, considerations impacting heat tracing
decisions include sample compositions and the expected
4.3 Calibration, maintenance, and performance protocols
variations, ambient temperature fluctuations, operating
provide a means to validate the analyzer operation.
pressures, and anticipated pressure differentials in sample
5. Significance and Use
system components. Sample filtration should be utilized as
required to remove particulate matter from the extracted
5.1 On-line, at-line, in-line and other near-real time moni-
sample. The sampling frequency relative to the process band-
toring systems that measure fuel gas characteristics such as the
width is critical to ensuring that the reported analytical results
heating value are prevalent in the natural gas and fuel gas
adequately represent the process being monitored. The
industries. The installation and operation of particular systems
Nyquist-Shannon sampling criterion of a sampling frequency
vary on the specific objectives, process type, regulatory
that exceeds twice the process bandwidth can be used to
requirements, and internal performance requirements needed
establish a minimum analytical cycle time. Sample handling
by the user. This protocol is intended to provide guidelines for
and conditioning system practices can be found in Practice
standardized start-up procedures, operating procedures, and
D5503.
qualityassurancepracticesforon-line,at-line,in-lineandother
near-real time heating value monitoring systems.
6.3.1 Carrier and Detector Gas Control—Constant flow
control of carrier and detector gases is critical for optimum and
6. Apparatus
consistent analytical performance. Control is achieved by use
of pressure regulators and fixed flow restrictors. Temperature
6.1 Instrument—Any instrument of standard manufacture,
with hardware necessary for interfacing to a natural gas or control is generally vital for ensuring consistent operation of
otherfuelgaspipelineandcontainingallthefeaturesnecessary these devices. The gas flow is measured by appropriate means
for the intended application(s) can be used. and adjusted as necessary. Mass flow controllers, capable of
D7164 − 10 (2015)
maintaining gas flow constant to 61 % at the flow rates 8. Equipment Siting and Installation
necessary for optimal instrument performance are generally
8.1 Asampleinletsystemcapableofoperatingcontinuously
used.
at or above the maximum column operating temperature is
6.3.2 Detectors—A thermal conductivity detector (TCD) is
necessary. The location of the sample inlet to the analyzer
commonly used. Other detectors, such as the flame ionization
relative to the sample extraction point is critical to obtaining
detector (FID), Practice E594, can be used but should at least
timely analytical results. Ideally, the analyzer is close coupled
meet TCD linearity, sensitivity, and selectivity in the selected
to the sample extraction point and there is an insignificant
application.
sampling lag time. Normally, the analyzer is mounted at some
distance away from the sample extraction point.This increased
6.4 Columns—A variety of columns, ranging from packed
distance represents increased lag time between when a sample
columns to open tubular capillary columns, can be used in the
is extracted from a process and when an analytical result is
determination of the Heating Value of a gaseous fuel. Packed
reported. The maximum allowable lag time depends on the
columns and open tubular capillary columns are covered in
specifics of the sampling location relative to the process being
Practices E260 and E1510 respectively. Columns should be
sampled. A fast loop sweep can be used to minimize the lag
conditioned in accordance with the manufacturer’s recommen-
time by creating a bypass loop that flows sample from the
dations. The selected column must provide retention and
process to the analyzer and is then returned to the process or is
resolution characteristics that satisfy the intended application.
vented.
The column must be inert towards gaseous fuel components. If
the selected column utilizes a liquid phase, bleeding at high
8.2 The sample should flow continuously without impedi-
temperatures must be sufficiently low so as to avoid the loss of
ment through the instrument sampling system. The sampling
instrument response during high temperature operation.
system should be capable of delivering a sample to the
detection system within the cycle time of the analyzer. Shorter
6.5 Data Acquisition—Data acquisition and storage can be
times may be required to meet the intended need.
accomplished using a number of devices and media. Following
are some examples.
8.3 A monitoring system pretest of both sampling and
6.5.1 Recorder—A0to1mVrangerecordingpotentiometer
analysis functions is critical to determining monitoring system
or equivalent, with a full-scale response time of2sor less can
characteristics, identify unforeseen factors affecting measure-
be used.
ment and to determine optimal operating conditions for the
6.5.2 Integrator—An electronic integrating device or com- intended use. This pretest is performed before the system is
puter can be used. For GC-based systems, it is suggested that
placedincontinuousserviceandmaybeperformedinavariety
the device and software have the following capabilities: of ways including a comparison of results to another instru-
6.5.2.1 Graphic presentation of chromatograms. ment already in service, analysis of a known gaseous sample
etc.
6.5.2.2 Digital display of chromatographic peak areas.
6.5.2.3 Identification of peaks by retention time or relative
9. Performance Tests
retention time, or both.
9.1 Thefollowingperformancetestsaresuggestedaspartof
6.5.2.4 Calculation and use of response factors.
an overall QA program. This list is not inclusive. The use of
6.5.2.5 External standard calculation and data presentation.
some, or all, of these performance tests, as well as tests not
6.5.2.6 Site-appropriate archives up to one month of all
specified, may be required or deemed appropriate and optional
runs. Archives could include raw data, derived component
by local, regional, state, and federal regulations, or a combi-
values or heating value results or both. Hourly, daily, and
nation thereof. Also the user’s judgment, manufacturer’s
monthly averages are included as requir
...
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 D7164 − 10 (Reapproved 2015)
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 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 and health practices and determine the applicability of regulatory
limitations prior to use.
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
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
D6122 Practice for Validation of the Performance of Multivariate Online, At-Line, and Laboratory Infrared Spectrophotometer
Based Analyzer Systems
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6621 Practice for Performance Testing of Process Analyzers for Aromatic Hydrocarbon Materials
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 7504 Gas Analysis-Vocabulary
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.
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 Jan. 1, 2010Nov. 1, 2015. Published February 2010December 2015. Originally approved in 2005. Last previous edition approved in 20052010
as D7164D7164–05.–10. DOI: 10.1520/D7164-10.10.1520/D7164-15.
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.
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.
3.1.1.1 Discussion—
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7164 − 10 (2015)
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.
3.2 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 Fuel is extracted from a process pipe or a pipeline and is transferred in a timely
manner to an analyzer sampling system. After appropriate conditioning steps that maintain the sample 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 value is calculated using the results of the compositional analysis using an appropriate
algorithm.
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-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.
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) 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.
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
D7164 − 10 (2015)
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 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. 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 is critical for optimum and
consistent analytical performance. Control is achieved by use of pressure regulators and fixed 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 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 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 recommendations. The
selected column must provide retention and resolution characteristics that satisfy the intended application. The column must be
inert 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 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 in the reference standard should be representative of the monitored gas. Concentrations of
major components are typically selected between one half and twice their expected concentration in the monitored gas. Standards
must be maintained as close as practicable to a constant temperature within the temperature range specified by the manufacturer
to ensure accuracy and stability.
8. Equipment Siting and Installation
8.1 A sample inlet system capable of operating continuously at or above the maximum column operating temperature is
necessary. The location of the sample inlet to the analyzer relative to the sample extraction point is critical to obtaining timely
analytical results. Ideally, the analyzer is close coupled to the sample extraction point and there is an insignificant sampling lag
time. Normally, the analyzer is mounted at some distance away from the sample extraction point. This increased distance represents
increased lag time between when a sample is extracted from a process and when an analytical result is reported. The maximum
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