ASTM D5454-04

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Designation:D5454–04
Standard Test Method for
Water Vapor Content of Gaseous Fuels Using Electronic
1
Moisture Analyzers
This standard is issued under the fixed designation D5454; 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 3.1.3 piezoelectric-type cell— sensor consists of a pair of
electrodes which support a quartz crystal (QCM) transducer.
1.1 This test method covers the determination of the water
When voltage is applied to the sensor a very stable oscillation
vaporcontentofgaseousfuelsbytheuseofelectronicmoisture
occurs. The faces of the sensor are coated with a hygroscopic
analyzers. Such analyzers commonly use sensing cells based
polymer.As the amount of moisture absorbed onto the polymer
on phosphorus pentoxide, P O , aluminum oxide, Al O,or
2 5 2 3
varies, a proportional change in the oscillation frequency is
silicon sensors piezoelectric-type cells and laser based tech-
produced.
nologies.
3.1.4 laser-type cell— consists of a sample cell with an
1.2 This standard does not purport to address all of the
optical head mounted on one end and a mirror mounted on the
safety concerns, if any, associated with its use. It is the
other. The optical head contains a NIR laser, which emits light
responsibility of the user of this standard to establish appro-
at a wavelength known to be absorbed by the water molecule.
priate safety and health practices and determine the applica-
Mounted along side the laser is a detector sensitive to NIR
bility of regulatory limitations prior to use.
wavelength light. Light from the laser passes through the the
2. Referenced Documents far end and returns to the detector in the optical head.Aportion
of the emitted light, proportional to the water molecules
2.1 ASTM Standards:
present, is absorbed as the light transits the sample cell and
D1142 Test Method for Water Vapor Content of Gaseous
returns to the detector.
Fuels by Measurement of Dew-Point Temperature
2
3.1.5 water content—water content is customarily ex-
D1145 Test Method for Sampling Natural Gas
pressed in terms of dewpoint, °F or °C, at atmospheric
D4178 Practice for Calibrating Moisture Analyzers
pressure, or the nonmetric term of pounds per million standard
D4888 Test Method for Water Vapor in Natural Gas Using
cubic feet, lb/MMSCF. The latter term will be used in this test
Length-of-Stain Detector Tubes
method because it is the usual readout unit for electronic
3. Terminology
analyzers. One lb/MMSCF = 21.1 ppm by volume or 16.1
3
mgm/m of water vapor.Analyzers must cover the range 0.1 to
3.1 Definitions of Terms Specific to This Standard:
50 lb/MMSCF.
3.1.1 capacitance-type cell—this cell uses aluminum coated
3.1.6 water dewpoint—the temperature (at a specified pres-
with Al O as part of a capacitor. The dielectric Al O film
2 3 2 3
sure) at which liquid water will start to condense from the
changes the capacity of the capacitor in relation to the water
water vapor present. Charts of dewpoints versus pressure and
vapor present. Unlike P O cells, this type is nonlinear in its
2 5
water content are found in Test Method D1142.
response. If silicon is used instead of aluminum, the silicon cell
gives improved stability and very rapid response.
4. Significance and Use
3.1.2 electrolytic-type cell—this cell is composed of two
4.1 Water content in fuel gas is the major factor influencing
noble metal electrode wires coated with P O .Abias voltage is
2 5
internal corrosion. Hydrates, a semisolid combination of hy-
applied to the electrodes, and water vapor chemically reacts,
drocarbons and water, will form under the proper conditions
generating a current between the electrodes proportional to the
causing serious operating problems. Fuel heating value is
water vapor present.
reduced by water concentration. Water concentration levels are
therefore frequently measured in natural gas systems. A com-
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous
mon pipeline specification is 4 to 7 lb/MMSCF. This test
Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of
method describes measurement of water vapor content with
Special Constituents of Gaseous Fuels.
Current edition approved Dec. 1, 2004. Published January 2005. Originally
direct readout electronic instrumentation.
approved in 1993. Last previous edition approved in 1999 as D5454–93(1999).
DOI: 10.1520/D5454-04.
2
Withdrawn.
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D5454–04
5. Apparatus 6.
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