ASTM D7607-11
(Test Method)Standard Test Method for Analysis of Oxygen in Gaseous Fuels (Electrochemical Sensor Method)
Standard Test Method for Analysis of Oxygen in Gaseous Fuels (Electrochemical Sensor Method)
SIGNIFICANCE AND USE
This test method is primarily used to monitor the concentration of oxygen in gases to verify gas quality for operational needs and contractual obligations. Oxygen content is a major factor influencing internal corrosion, fuel quality, gas quality, and user and operator safety.
SCOPE
1.1 This test method is for the determination of oxygen (O2) in gaseous fuels and fuel type gases. It is applicable to the measurement of oxygen in natural gas and other gaseous fuels. This method can be used to measure oxygen in helium, hydrogen, nitrogen, argon, carbon dioxide, mixed gases, process gases, and ambient air. The applicable range is 0.1 ppm(v) to 25% by volume.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the 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.
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Standards Content (Sample)
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Designation: D7607 − 11
StandardTest Method for
Analysis of Oxygen in Gaseous Fuels (Electrochemical
Sensor Method)
This standard is issued under the fixed designation D7607; 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 3.2.2 span calibration—The adjustment of the transmitter
electronics to the sensor’s signal output for a given oxygen
1.1 This test method is for the determination of oxygen (O )
standard.
in gaseous fuels and fuel type gases. It is applicable to the
3.2.3 zero calibration—The adjustment of the transmitter
measurement of oxygen in natural gas and other gaseous fuels.
electronics to the sensor’s signal output for a sample gas
This method can be used to measure oxygen in helium,
containing less than 0.1ppm(v) oxygen.
hydrogen, nitrogen, argon, carbon dioxide, mixed gases, pro-
cess gases, and ambient air.The applicable range is 0.1 ppm(v)
4. Summary of Test Method
to 25% by volume.
4.1 Measurement of oxygen is accomplished by comparing
1.2 The values stated in either SI units or inch-pound units
the electrical signal produced by an unknown sample with that
are to be regarded separately as standard. The values stated in
of a known standard using an oxygen specific electrochemical
each system may not be exact equivalents; therefore, each
sensor. A gaseous sample at constant flow and temperature is
system shall be used independently of the other. Combining
passed over the electrochemical cell. Oxygen diffuses into the
values from the two systems may result in non-conformance
sensor and reacts chemically at the sensing electrode to
with the standard.
produce an electrical current output proportional to the oxygen
1.3 This standard does not purport to address all of the
concentration in the gas phase. Experience has shown that the
safety concerns, if any, associated with its use. It is the
types of sensors supplied with equipment used in this standard
responsibility of the user of this standard to establish appro-
typically have a linear response over the ranges of application
priate safety and health practices and determine the applica-
which remains stable during the sensor’s useful life. The
bility of regulatory limitations prior to use.
analyzer consists of a sensor, a sample flow system, and the
electronics to accurately determine the sensor signal.
2. Referenced Documents
2.1 ASTM Standards: 5. Significance and Use
D4150 Terminology Relating to Gaseous Fuels
5.1 This test method is primarily used to monitor the
D5503 Practice for Natural Gas Sample-Handling and Con-
concentration of oxygen in gases to verify gas quality for
ditioning Systems for Pipeline Instrumentation
operational needs and contractual obligations. Oxygen content
isamajorfactorinfluencinginternalcorrosion,fuelquality,gas
3. Terminology
quality, and user and operator safety.
3.1 For general terminology see Terminology D4150.
6. Interferences
3.2 Definitions:
6.1 Interfering gases such as oxides of sulfur, oxides of
3.2.1 electrochemical sensor—Achemical sensor that quan-
nitrogen, and hydrogen sulfide can produce false readings and
titatively measures an analyte by the electrical output produced
by the sensor. reduce the expected life of the sensor. Scrubbers are used to
remove these compounds. Special sensors suitable for gas
containing high fractions of carbon dioxide are available from
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous
manufacturers.
Fuels and is the direct responsibility of Subcommittee D03.12 on On-Line/At-Line
Analysis of Gaseous Fuels.
7. Apparatus
Current edition approved June 1, 2011. Published July 2011. DOI: 10.1520/
D7607-11.
7.1 Sensor—The sealed sensor is contained in a housing
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
constructed of stainless steel or other non-permeable material.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
The sensor contains a cathode and an anode in an electrolyte
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. solution.Afluorocarbonmembraneallowstheoxygenfromthe
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7607 − 11
sample to diffuse into the sensor. Oxygen in the sample is electrolyte, and tolerances of the electronic components of the
reduced at the cathode and is simultaneously oxidized at the analyzer. Zero calibration is required after a new sensor is
anode. The electrons released at the surface of the anode flow installed.
to the cathode surface when an external electrical path is 9.1.1 The sensor is exposed to the sample gas with less than
provided. The current is proportional to the amount of oxygen 0.1 ppm oxygen. Follow the instrument manufacturer’s recom-
reaching the cathode and is used to measure the oxygen mended inlet sample flow rate and pressure, usually a flow rate
concentration in the gas phase. The electrochemical reactions of 1 liter per min or 2 SCFH is recommended for optimum
for a lead anode cell are as follows: performance.
9.1.2 Allow the analyzer output to stabilize. This may take
(cathode half reaction)
O 12H O14e →4OH
2 2
up several hours if a new sensor has been installed.
9.1.3 Follow the instrument manufacturer’s instructions for
(anode half reaction)
2 2
2Pb14OH →2PbO12H O14e
zero calibration of the instrument.
(overall cell reaction)
9.2 Span Calibration of Instrument—Certified gas standards
2Pb1O→2PbO
can be obtained from a gas standard vendor. Span calibration is
required after a new sensor is installed.
Any electrochemical cell with different materials can be em-
9.2.1 Flow the gas standard through the analyzer. The
ployed if the cell can give the same performance for selec-
standard should approximate the sample gas to be tested and
tive oxygen detection with similar sensitivity.
contain oxygen levels in the range of interest of the user.
7.2 Electronics—Various electronic circuits are used to
9.2.2 Allow the analyzer output to stabilize. This may take
amplify and filter the sensor signal. The signal output may be
several min.
corrected for the gas sample temperature.
9.2.3 Follow the instrument manufacturer’s instructions for
7.3 Output—Automatic digital or range selectable analog
span calibration of the instrument.
display of parts per million or percent oxygen reading by
volume. 10. Conditioning
10.1 Purge oxygen free or low ppm oxygen gas through the
7.4 Sampling System—Samplegasmustbeintroducedtothe
sensor of the analyzer. A flow control metering valve is apparatus if it is not to be used immediately after calibration.
Allow the display reading to stabilize before disconnecting.
positioned upstream of the analyzer to provide a gas sample
flow rate of 0.5 to 2 L/min [1 to 5 SCFM].
...
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