ASTM D7607-11

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Designation: D7607 − 11
StandardTest Method for
Analysis of Oxygen in Gaseous Fuels (Electrochemical
1
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 )
2
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
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
1
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
2
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
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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
...