ASTM D1142-95(2021)

Standard Test Method for Water Vapor Content of Gaseous Fuels by<brk/> Measurement of Dew-Point Temperature

SIGNIFICANCE AND USE
3.1 Generally, contracts governing the pipeline transmission of natural gas contain specifications limiting the maximum concentration of water vapor allowed. Excess water vapor can cause corrosive conditions, degrading pipelines and equipment. It can also condense and freeze or form methane hydrates causing blockages. Water–vapor content also affects the heating value of natural gas, thus influencing the quality of the gas. This test method permits the determination of water content of natural gas.
SCOPE
1.1 This test method covers the determination of the water vapor content of gaseous fuels by measurement of the dew-point temperature and the calculation therefrom of the water vapor content.  
Note 1: Some gaseous fuels contain vapors of hydrocarbons or other components that easily condense into liquid and sometimes interfere with or mask the water dew point. When this occurs, it is sometimes very helpful to supplement the apparatus in Fig. 1 with an optical attachment that uniformly illuminates the dew–point mirror and also magnifies the condensate on the mirror. With this attachment it is possible, in some cases, to observe separate condensation points of water vapor, hydrocarbons, and glycolamines as well as ice points. However, if the dew point of the condensable hydrocarbons is higher than the water vapor dew point, when such hydrocarbons are present in large amounts, they may flood the mirror and obscure or wash off the water dew point. Best results in distinguishing multiple component dew points are obtained when they are not too closely spaced.
FIG. 1 Bureau of Mines Dew-Point Apparatus  
Note 2: Condensation of water vapor on the dew-point mirror may appear as liquid water at temperatures as low as 0 to −10°F (−18 to −23°C). At lower temperatures an ice point rather than a water dew point likely will be observed. The minimum dew point of any vapor that can be observed is limited by the mechanical parts of the equipment. Mirror temperatures as low as −150°F (−100°C) have been measured, using liquid nitrogen as the coolant with a thermocouple attached to the mirror, instead of a thermometer well.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Jun-2021
• ICS: 75.160.30 - Gaseous fuels
• Technical Committee: D03 - Gaseous Fuels

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D1142 − 95 (Reapproved 2021)
Standard Test Method for
Water Vapor Content of Gaseous Fuels by
1
Measurement of Dew-Point Temperature
This standard is issued under the fixed designation D1142; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2. Terminology
1.1 This test method covers the determination of the water 2.1 Definitions of Terms Specific to This Standard:
vapor content of gaseous fuels by measurement of the dew- 2.1.1 saturated water vapor or equilibrium water–vapor
point temperature and the calculation therefrom of the water content—the water vapor concentration in a gas mixture that is
vapor content. in equilibrium with a liquid phase of pure water that is
saturated with the gas mixture. When a gas containing water
NOTE 1—Some gaseous fuels contain vapors of hydrocarbons or other
vapor is at the water dew-point temperature, it is said to be
components that easily condense into liquid and sometimes interfere with
saturated at the existing pressure.
or mask the water dew point. When this occurs, it is sometimes very
helpful to supplement the apparatus in Fig. 1 with an optical attachment
2.1.2 specific volume—of a gaseous fuel, the volume of the
that uniformly illuminates the dew–point mirror and also magnifies the
gas in cubic feet per pound.
condensate on the mirror. With this attachment it is possible, in some
cases, to observe separate condensation points of water vapor,
2.1.3 water dew-point temperature— of a gaseous fuel, the
hydrocarbons, and glycolamines as well as ice points. However, if the dew
temperature at which the gas is saturated with water vapor at
point of the condensable hydrocarbons is higher than the water vapor dew
the existing pressure.
point, when such hydrocarbons are present in large amounts, they may
flood the mirror and obscure or wash off the water dew point. Best results
in distinguishing multiple component dew points are obtained when they 3. Significance and Use
are not too closely spaced.
3.1 Generally, contracts governing the pipeline transmission
NOTE 2—Condensation of water vapor on the dew-point mirror may
of natural gas contain specifications limiting the maximum
appear as liquid water at temperatures as low as 0 to −10°F (−18
to −23°C). At lower temperatures an ice point rather than a water dew concentration of water vapor allowed. Excess water vapor can
point likely will be observed. The minimum dew point of any vapor that
cause corrosive conditions, degrading pipelines and equipment.
can be observed is limited by the mechanical parts of the equipment.
It can also condense and freeze or form methane hydrates
Mirror temperatures as low as −150°F (−100°C) have been measured,
causing blockages. Water–vapor content also affects the heat-
using liquid nitrogen as the coolant with a thermocouple attached to the
ing value of natural gas, thus influencing the quality of the gas.
mirror, instead of a thermometer well.
This test method permits the determination of water content of
1.2 This standard does not purport to address all of the
natural gas.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Apparatus
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4.1 Any properly constructed dew-point apparatus may be
1.3 This international standard was developed in accor-
used that satisfies the basic requirements that means must be
dance with internationally recognized principles on standard-
provided:
ization established in the Decision on Principles for the
4.1.1 To permit a controlled flow of gas to enter and leave
Development of International Standards, Guides and Recom-
the apparatus while the apparatus is at a temperature at least
mendations issued by the World Trade Organization Technical
3°F above the dew point of the gas.
Barriers to Trade (TBT) Committee.
4.1.2 To cool and control the cooling rate of a portion
(preferably a small portion) of the apparatus, with which the
flowing gas comes in contact, to a temperature low enough to
1
cause vapor to condense from the gas.
This test method is under the jurisdiction of ASTM Committee D03 on Gaseous
Fuels and is the direct responsibility of Subcommittee D03.06.04 on Analysis by
4.1.3 To observe the deposition o
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