ASTM D5454-11(2020),Standard Test Method for Water Vapor Content of Gaseous Fuels Using Electronic Moisture Analyzers.
ASTM D5454-11(2020) covers the determination of the water vapor content of gaseous fuels by the use of electronic moisture analyzers.
Calibration
A calibration technique is described in Practice D4178 that should be used to verify the accuracy of the analyzer. This method uses the known vapor pressure of water at 0C and mixes wet gas and dry gas to make up the total pressure so that a standard gas of known water concentration is achieved.
Instruments very sensitive to sample flow must be compensated for barometric pressure.
A commercially made water vapor calibrator is shown in Fig. 1, which uses essentially the same technique. This method is useful only between 5 to 50 1b/MMSCF.
Low-range water vapor standards may be obtained by the use of water permeation tubes. Permeation rates must be established by tube weight loss.
Compressed gas water vapor standards may be used,provided they are checked by an independent method once a month.
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