Standard Test Method for Water Vapor Content of Gaseous Fuels Using Electronic Moisture Analyzers

SIGNIFICANCE AND USE
Water content in fuel gas is the major factor influencing internal corrosion. Hydrates, a semisolid combination of hydrocarbons and water, will form under the proper conditions causing serious operating problems. Fuel heating value is reduced by water concentration. Water concentration levels are therefore frequently measured in natural gas systems. A common pipeline specification is 4 to 7 lb/MMSCF. This test method describes measurement of water vapor content with direct readout electronic instrumentation.
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 piezoelectric-type cells and laser based technologies.
1.2 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

Status
Historical
Publication Date
31-May-2011
Technical Committee
Current Stage
Ref Project

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ASTM D5454-11e1 - Standard Test Method for Water Vapor Content of Gaseous Fuels Using Electronic Moisture Analyzers
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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´1
Designation: D5454 − 11
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
ε NOTE—Fig. 1 was editorially updated in July 2011.
1. Scope 3.1.2 electrolytic-type cell—this cell is composed of two
noble metal electrode wires coated with P O .Abias voltage is
2 5
1.1 This test method covers the determination of the water
applied to the electrodes, and water vapor chemically reacts,
vaporcontentofgaseousfuelsbytheuseofelectronicmoisture
generating a current between the electrodes proportional to the
analyzers. Such analyzers commonly use sensing cells based
water vapor present.
on phosphorus pentoxide, P O , aluminum oxide, Al O,or
2 5 2 3
3.1.3 piezoelectric-type cell— sensor consists of a pair of
silicon sensors piezoelectric-type cells and laser based tech-
electrodes which support a quartz crystal (QCM) transducer.
nologies.
When voltage is applied to the sensor a very stable oscillation
1.2 This standard does not purport to address all of the
occurs. The faces of the sensor are coated with a hygroscopic
safety concerns, if any, associated with its use. It is the
polymer.As the amount of moisture absorbed onto the polymer
responsibility of the user of this standard to establish appro-
varies, a proportional change in the oscillation frequency is
priate safety and health practices and determine the applica-
produced.
bility of regulatory limitations prior to use.
3.1.4 laser-type cell— consists of a sample cell with an
2. Referenced Documents
optical head mounted on one end and a mirror mounted on the
2
other; however, some models will not need a mirror to reflect
2.1 ASTM Standards:
the light wavelength emitted from the laser. The optical head
D1142 Test Method for Water Vapor Content of Gaseous
contains a NIR laser, which emits light at a wavelength known
Fuels by Measurement of Dew-Point Temperature
to be absorbed by the water molecule. Mounted, the laser is a
D1145 Test Method for Sampling Natural Gas (Withdrawn
3
detectorsensitivetoNIRwavelengthlight.Lightfromthelaser
1986)
passes through the far end and returns to the detector in the
D4178 Practice for Calibrating Moisture Analyzers
optical head.Aportion of the emitted light, proportional to the
3. Terminology water molecules present, is absorbed as the light transits the
sample cell and returns to the detector.
3.1 Definitions of Terms Specific to This Standard:
3.1.5 water content—watercontentiscustomarilyexpressed
3.1.1 capacitance-type cell—this cell uses aluminum coated
in terms of dewpoint, °F or °C, at atmospheric pressure, or the
with Al O as part of a capacitor. The dielectric Al O film
2 3 2 3
nonmetric term of pounds per million standard cubic feet,
changes the capacity of the capacitor in relation to the water
lb/MMSCF. The latter term will be used in this test method
vapor present. Silicone cells also operate on this principal by
because it is the usual readout unit for electronic analyzers.
reporting a capacitance change when adsorbing or desorbing
3
One lb/MMSCF = 21.1 ppm by volume or 16.1 mgm/m of
water vapor.
water vapor. Analyzers must cover the range 0.1 to 50
lb/MMSCF.
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous
3.1.6 water dewpoint—the temperature (at a specified pres-
Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of
sure) at which liquid water will start to condense from the
Special Constituents of Gaseous Fuels.
Current edition approved July 11, 2011. Published July 2011. Originally
water vapor present. Charts of dewpoints versus pressure and
approved in 1993. Last previous edition approved in 2004 as D5454–04. DOI:
water content are found in Test Method D1142.
10.1520/D5454-11E01.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4. Significance and Use
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
4.1 Water content in fuel gas is the major factor influencing
the ASTM website.
3
internal corrosion. Hydrates, a semisolid combination of hy-
The last approved version of this historical standard is referenced on
www.astm.org. drocarbons and water, will form under the proper conditions
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D5454 − 11
causing serious op
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