ASTM D5454-93(1999)
(Test Method)Standard Test Method for Water Vapor Content of Gaseous Fuels Using Electronic Moisture Analyzers
Standard Test Method for Water Vapor Content of Gaseous Fuels Using Electronic Moisture Analyzers
SCOPE
1.1 This test method covers the determination of the water vapor content of gaseous fuels by the use of electronic moisture analyzers. Such analyzers commonly use sensing cells based on phosphorus pentoxide, P2O5, aluminum oxide, Al2O3, or silicon sensors.
1.2 This standard does not purport to address all of the safety problems, 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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Designation:D5454–93 (Reapproved 1999)
Standard Test Method for
Water Vapor Content of Gaseous Fuels Using Electronic
Moisture Analyzers
This standard is issued under the fixed designation D 5454; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope pressure, or the nonmetric term of pounds per million standard
cubic feet, lb/MMSCF. The latter term will be used in this test
1.1 This test method covers the determination of the water
method because it is the usual readout unit for electronic
vaporcontentofgaseousfuelsbytheuseofelectronicmoisture
analyzers. One lb/MMSCF = 21.1 ppm by volume or 16.1
analyzers. Such analyzers commonly use sensing cells based
mgm/m of water vapor.Analyzers must cover the range 0.1 to
on phosphorus pentoxide, P O , aluminum oxide, Al O,or
2 5 2 3
50 lb/MMSCF.
silicon sensors.
3.1.4 water dewpoint—the temperature (at a specified pres-
1.2 This standard does not purport to address all of the
sure) at which liquid water will start to condense from the
safety concerns, if any, associated with its use. It is the
water vapor present. Charts of dewpoints versus pressure and
responsibility of the user of this standard to establish appro-
water content are found in Test Method D 1142.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Significance and Use
2. Referenced Documents 4.1 Water content in fuel gas is the major factor influencing
internal corrosion. Hydrates, a semisolid combination of hy-
2.1 ASTM Standards:
drocarbons and water, will form under the proper conditions
D 1142 Test Method for Water Vapor Content of Gaseous
causing serious operating problems. Fuel heating value is
Fuels by Measurement of Dew-Point Temperature
3 reduced by water concentration. Water concentration levels are
D 1145 Test Method for Sampling Natural Gas
therefore frequently measured in natural gas systems. A com-
D 4178 Practice for Calibrating Moisture Analyzers
mon pipeline specification is 4 to 7 lb/MMSCF. This test
D 4888 Test Method for Water Vapor In Natural Gas Using
method describes measurement of water vapor content with
Length-of-Stain Detector Tubes
direct readout electronic instrumentation.
3. Terminology
5. Apparatus
3.1 Definitions of Terms Specific to This Standard:
5.1 The moisture analyzer and sampling system will have
3.1.1 capacitance-type cell—this cell uses aluminum coated
the following general specifications:
with Al O as part of a capacitor. The dielectric Al O film
2 3 2 3
5.1.1 Sampling System—Most errors involved with mois-
changes the capacity of the capacitor in relation to the water
ture analysis can be eliminated with a proper sampling system.
vapor present. Unlike P O cells, this type is nonlinear in its
2 5
5.1.1.1 A pipeline sample should be obtained with a probe
response. If silicon is used instead of aluminum, the silicon cell
per Method D 1145. The sample temperature must be main-
gives improved stability and very rapid response.
tained 2°C (3°F) above the dewpoint of the gas to prevent
3.1.2 electrolytic-type cell—this cell is composed of two
condensation in the sample line or analyzer. Use of insulation
noble metal electrode wires coated with P O .Abias voltage is
2 5
or heat tracing is recommended at cold ambient temperatures.
applied to the electrodes, and water vapor chemically reacts,
5.1.1.2 Analyzer sensors are very sensitive to contamina-
generating a current between the electrodes proportional to the
tion. Any contaminants injurious to the sensor must be re-
water vapor present.
moved from the sample stream before reaching the sensor.This
3.1.3 water content—water content is customarily ex-
must be done with minimum impact on accuracy or time of
pressed in terms of dewpoint, °F or °C, at atmospheric
response. If the contaminant is an aerosol of oil, glycol, and so
forth, a coalescing filter or semipermeable membrane separator
This test method is under the jurisdiction ofASTM Committee D-3 on Gaseous
must be used.
Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of
5.1.2 Construction—Sampling may be done at high or low
Special Constituents of Gaseous Fuels.
Current edition approved Sept. 15, 1993. Published November 1993. pressure. All components subject to high pressure must be
Annual Book of ASTM Standards, Vol 05.06.
rated accordingly. To minimize diffusion and absorption, all
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