ASTM D4888-88(1999)

Standard Test Method for Water Vapor in Natural Gas Using Length-of-Stain Detector Tubes

SCOPE
1.1 This test method covers a procedure for rapid and simple field determination of water vapor in natural gas pipelines. Available detector tubes provide a total measuring range of 0.1 to 40 mg/L, although the majority of applications will be on the lower end of this range (that is, under 0.5 mg/L). At least one manufacturer provides tubes that read directly in pounds of water per million cubic feet of gas. See Note 1.
1.2 Detector tubes are usually subject to interferences from gases and vapors other than the target substance. Such interferences may vary among brands due to the use of different detection methods. Consult manufacturer's instructions for specific interference information. Alcohols and glycols will cause interferences on some water vapor tubes due to the presence of the hydroxyl group on those molecules.
1.3 This standard does not purport to address all of the safety problems, 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: 09-Nov-1999
• ICS: 75.060 - Natural gas
• Technical Committee: D03 - Gaseous Fuels

Relations

• Replaced By: ASTM D4888-06 - Standard Test Method for Water Vapor in Natural Gas Using Length-of-Stain Detector Tubes
• Effective Date: 01-Jun-2006

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D4888–88(Reapproved1999)
Standard Test Method for
Water Vapor in Natural Gas Using Length-of-Stain Detector
Tubes
This standard is issued under the fixed designation D 4888; 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 (e) indicates an editorial change since the last revision or reapproval.
factor is 1 mg/L 5 62.3 lb/MMCF (7 lb/MMCF 5 0.11 mg/L).
1. Scope
1.1 This test method covers a procedure for rapid and
3. Significance and Use
simple field determination of water vapor in natural gas
3.1 The measurement of water vapor in natural gas is
pipelines. Availabel detector tubes provide a total measuring
important because of the gas quality specifications, the corro-
range of 0.1 to 40 mg/L, although the majority of applications
sive nature of water vapor on pipeline materials, and the effects
will be on the lower end of this range (that is, under 0.5 mg/L).
of water vapor on utilization equipment.
At least one manufacturer provides tubes that read directly in
3.2 This test method provides inexpensive field screening of
pounds of water per million cubic feet of gas. See Note 1.
water vapor. The system design is such that it may be used by
1.2 Detector tubes are usually subject to interferences from
nontechnical personnel with a minimum of proper training.
gases and vapors other than the target substance. Such inter-
ferencesmayvaryamongbrandsbecauseoftheuseofdifferent
4. Apparatus
detection methods. Consult manufacturer’s instructions for
4.1 Length-of-Stain Detector Tubes—A sealed glass tube
specific interference information. Alcohols and glycols will
with the breakoff tips sized to fit the tube holder of the pump.
cause interferences on some water vapor tubes because of the
Thereagentlayerinsidethetube,typicallyasilicagelsubstrate
presence of the hydroxyl group on those molecules.
coated with the active chemical, must be specific for water
1.3 This standard does not purport to address all of the
vapor and produce a distinct color change when exposed to a
safety concerns, if any, associated with its use. It is the
sample of gas containing water vapor. Any substances known
responsibility of the user of this standard to establish appro-
to interfere must be listed in the instructions accompanying the
priate safety and health practices and determine the applica-
tubes. A calibration scale should be marked directly on the
bility of regulatory limitations prior to use.
tube; however, other markings that provide for ready interpre-
tation of water vapor content from a separate calibration scale
2. Summary of Test Method
supplied with the tubes shall be acceptable. The calibration
2.1 The sample is passed through a detector tube filled with
scale shall correlate water vapor concentration to the length of
a specially prepared chemical. Any water vapor present in the
the color stain. Shelf life of the detector tubes must be a
sample reacts with the chemical to produce a color change or
minimum of two years from date of manufacture when stored
stain. The length of the stain produced in the detector tube,
according to manufacturers’ recommendations.
when exposed to a measured volume of sample, is directly
4.2 Detector Tube Pump—A hand-operated pump of a
proportional to the amount of water vapor present in the
piston or bellows type. It must be capable of drawing 100 mL
sample. A hand-operated piston or bellows-type pump is used
per stroke of sample through the detector tube with a volume
to draw a measured volume of sample through the tube at a
tolerance of 65 mL. It must be specifically designed for use
controlled rate of flow. The length of stain produced is
with detector tubes.
converted to milligrams per litre of H O by comparison to a
calibration scale supplied by the manufacturer for each box of NOTE 2—A detector tube and pump together form a unit and must be
used as such. Each manufacturer calibrates detector tubes to match the
detection tubes. The system is direct reading, easily portable,
flow characteristics of its specific pump. Crossing brands of pumps and
and completely suited to making rapid spot checks for water
tubes is not permitted, as considerable loss of system accuracy is likely to
vapor under field conditions.
occur.
NOTE 1—Detector tubes are available with calibration scales printed in
4.3 Gas Sampling Chamber—Any container that provides
pounds of water per million cubic feet of gas (lb/MMCF). The conversion
for access of the detector tube into a uniform flow of sample
gas at atmospheric pressure and isolates the sample from the
This test method is under the jurisdiction of Committee D-3 on Gaseous Fuels
and is the direct responsibility of Subcommittee D03.05 Determination of Special
Constituents of Gaseous Fuels. Direct Reading Colorimetric Indicator Tubes Manual, First ed., American
Current edition approved Dec. 30, 1988. Published February 1989. Industrial Hygiene Association, Akron, OH 44311, 1976.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4888
surrounding atmosphere. A stainless steel needle valve (or 5.3 Open source valve. Open needle valve enough to obtain
pressure regulator) is placed between the source valve and the positive flow of gas chamber, in accordance with 4.3. Purge the
sampling chamber for the purpose of throttling the sample container for at least 3 min (Fig. 1). Purge for at least 10 min
flow.Flowrateshouldapproximateonetotwovolumechanges if a polyethylene bottle is used.
per minute or, at minimum, provide exit gas flow throughout 5.4 Before each series of measurements, test the pump for
the detector tube sampling period. leaks by operating it with an unbroken tube in place. Consult
manufacturers’ instructions for leak check procedure details
NOTE 3—Asuitable chamber may be devised from a polyethylene wash
and for maintenance instruction if leaks are detected. The leak
bottle of nominal 500-mL (16-oz) or 1-L (32-oz) size. The wash bottle’s
check typically takes 1 min.
internal delivery tube provides for delivery of sample gas to the bottom of
the bottle. A ⁄2-in. hole cut in the bottle’s cap provides access for the 5.5 Select the t
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