ASTM D4888-20

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: D4888 − 20
Standard Test Method for
Water Vapor in Natural Gas Using Length-of-Stain Detector
1
Tubes
This standard is issued under the fixed designation D4888; 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. Terminology
1.1 This test method covers a procedure for rapid and
3.1 Definitions—For definitions of general terms used in
simple field determination of water vapor in natural gas D03 Gaseous Fuels standards, refer to Terminology D4150.
pipelines. Available detector tubes provide a total measuring
range of 0.1 to 40 mg/L, although the majority of applications 4. Summary of Test Method
will be on the lower end of this range (that is, under 0.5 mg/L).
4.1 The sample is passed through a detector tube filled with
At least one manufacturer provides tubes that read directly in
a specially prepared chemical. Any water vapor present in the
pounds of water per million cubic feet of gas. See Note 1.
sample reacts with the chemical to produce a color change or
1.2 Detector tubes are usually subject to interferences from stain. The length of the stain produced in the detector tube,
gases and vapors other than the target substance. Such inter-
when exposed to a measured volume of sample, is directly
ferences may vary among brands because of the use of different proportional to the amount of water vapor present in the
detection methods. Consult manufacturer’s instructions for
sample. A hand-operated piston or bellows-type pump is used
specific interference information. Alcohols and glycols will to draw a measured volume of sample through the tube at a
cause interferences on some water vapor tubes because of the
controlled rate of flow. The length of stain produced is
presence of the hydroxyl group on those molecules. converted to milligrams per liter of H O by comparison to a
2
calibration scale supplied by the manufacturer for each box of
1.3 Units—The values stated in SI units are to be regarded
detection tubes. The system is direct reading, easily portable,
as the standard.
and completely suited to making rapid spot checks for water
1.4 This standard does not purport to address all of the
vapor under field conditions.
safety concerns, if any, associated with its use. It is the
NOTE 1—Detector tubes are available with calibration scales printed in
responsibility of the user of this standard to establish appro-
pounds of water per million cubic feet of gas (lb/MMCF). The conversion
priate safety, health, and environmental practices and deter-
factor is 1 mg/L = 62.3 lb/MMCF (7 lb/MMCF = 0.11 mg ⁄L).
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
5. Significance and Use
dance with internationally recognized principles on standard-
5.1 The measurement of water vapor in natural gas is
ization established in the Decision on Principles for the
important because of the gas quality specifications, the corro-
Development of International Standards, Guides and Recom-
sive nature of water vapor on pipeline materials, and the effects
mendations issued by the World Trade Organization Technical
of water vapor on utilization equipment.
Barriers to Trade (TBT) Committee.
5.2 This test method provides inexpensive field screening of
2. Referenced Documents
water vapor. The system design is such that it may be used by
2
2.1 ASTM Standards:
nontechnical personnel with a minimum of proper training.
D4150 Terminology Relating to Gaseous Fuels
6. Apparatus
1
This test method is under the jurisdiction of ASTM Committee D03 on Gaseous
6.1 Length-of-Stain Detector Tubes—A sealed glass tube
Fuels and is the direct responsibility of Subcommittee D03.06.03 on Analysis by
with the breakoff tips sized to fit the tube holder of the pump.
Spectroscopy.
The reagent layer inside the tube, typically a silica gel substrate
Current edition approved Dec. 15, 2020. Published January 2021. Originally
coated with the active chemical, must be specific for water
approved in 1988. Last previous edition approved in 2015 as D4888 – 06(2015).
DOI: 10.1520/D4888-20.
vapor and produce a distinct color change when exposed to a
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
sample of gas containing water vapor. Any substances known
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
to interfere must be listed in the instructions accompanying the
Standards volume inform
...