ASTM D2725-87(1992)E01

Test Method for Hydrogen Sulfide in Natural Gas (Methylene Blue Method) (Withdrawn 1996)

General Information

• Status: Withdrawn
• Withdrawal Date: 09-Nov-1996
• Technical Committee: D03 - Gaseous Fuels

Standards Content (Sample)

ASTM D2725 87 - 075=l5l,O 05117458 72L -
AMERICAN SOCIETY FOR TESTtNG AND MATERIALS
Designation: D 2725 - 87 (Reapproved 1992)E1
1916 Race St. Philadelphia, Pa 19103
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
If not listed in Q-a current combined index, will appear in the next editbn.
Standard Test Method for
Hydrogen Sulfide in Natural Gas (Methylene Blue Method)’
This standard is issued under the fixed designation D 2725; 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 (0 indicates an editorial change since the last revision or reapproval.
(1 Nora-Editorial changes were made throughout in September 1992.
sion below 567 nm and more than 80 % transmission from
1. Scope
608 to 750 nm, or an interference filter with the peak of its
1.1 This test method covers the determination of hy-
band pass at any wavelength between 620 and 750 nm and
drogen sulfide in natural gas containing not more than 1.0
having less than 0.5 % transmission below 570 nm, shall be
grain of hydrogen sulfide per 100 ft3 (23 mg/m3 or 16 ppm
used with instruments in which the spectral range is isolated
volume).
by filters. A photometer equipped with absorption cells with
1.2 The values stated in inch-pound units are to be
at least 20 to 25-mm path lengths is recommended.
regarded as the standard. The values given in parentheses are
4.3 Wet Test Meter-O.05 or 0.1 ft3 (1.5 or 3 L) per
for information only.
revolution, or calibrated aspirator bottle of approximately
1.3 This standard does not purport to address all of the
0, l-ft3 capacity. (A 1 L per revolution meter is satisfactory.)
safety problems, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate sdety and health practices and determine the applica-
5. Reagents
bility of regulatory limitations prior to use. For a specific
5.1 Purity of Reagents-Reagent grade chemicals shah be
hazard statement, see Note 1.
used in all tests. Unless otherwise indicated, it is intended
that all reagents shall conform to the specifications of the
2. Referenced Documents
Committee on Analytical Reagents of the American Chem-
2.1 ASTM Standards:
ical Society, where such specifications are availablee5 Other
D 1193 Specification for Reagent Waterz
grades may be used, provided it is first ascertained that the
D 303 1 Test Method for Total Sulfur in Natural Gas by
reagent is of sufficiently high purity to permit its use without
Hydrogenation3
lessening the accuracy of the determination.
5.2 Purity of Water-Unless otherwise indicated, refer-
3. Summary of Test Method
ences to water shall be understood to mean reagent water
3.1 A measured sample of the gas is bubbled through zinc
conforming to Type ? of Specification D 1193.
acetate solution, Acid solutions of N,N-dimethyl-pphe-
5.3 Ferric Chloride Solution (27 g/L)-Dissolve 2.7 g of
nylenediamine, and ferric chloride are added to the zinc
ferric chloride (FeC13.6H20) in 50 mL of hydrochloric acid
acetate solution to react with zinc sulfide to form the
(HCI) (sp gr 1.19) and dilute to 100 mL with water.
methylene blue dye. The methylene blue is determined by
5.4 Hydrogen Sulfde6-Cylinder gas, 99.5 % minimum.
measurement of optical absorbance of the solution at a
5.5 Iodine, Standard Solution (0.01 N&Dissolve 1.27 g
specified wavelength or wavelength range.
of iodine and 4 g of potassium iodide (RI) in water and dilute
to 1 L. Store in a cool place in a dark-colored, glass-
4. Apparatus
stoppered bottle. Standardize as follows: Pipet 25 mL of
4.1 Absorption Flask (Fig. l)-This flask is a 50-mL
iodine solution into a 250-mL Erlenmeyer or iodine flask,
volumetric flask with an enlarged neck (Engler or Redwood
add 25 to 50 mL of water and 5 mL of HCI. Titrate with
type), and is fitted with an open-end bubbler tube.
standard thiosulfate solution until the iodine solution fades
4.2 Photoelectric Photometer or Spectrophotometer-Any
to a pale yellow. Add 5 mL of starch solution and titrate to
instrument designed for the requirements of practical ab-
the disappearance of the blue color. The end point will be
sorption photometry and suitable for measurements at sharper if the solution is cooled to 5°C or lower.
approximately 745 nm may be used. A glass color filte# of 5.6 N,N-dimethyl-p-phenylenediamine sulfate, purtjied
low wavelength cutoff type having less than 37 % transmis-
(Diamine Solution)-Dissolve 0.11 g in 100 mL of sulfuric
t This test method is under the jurisdiction of ASTM Committee D-3 on
5 “Reagent Chemicals, American Chemical Society Specitications,” Am. Chem-
Gaseous Fuels and is the direct responsibility of Subcommittee DO3.05 on
ical Sot., Washington, DC. For suggestions on the testing of reagents not listed by
Determination of Special Constituents of Gaseous Fuels.
the American Chemical Society, see “Reagent Chemicals and Standards,” by
Current edition approved Jan. 30, 1987. Published March 1987. Originally
Joseph Rosin, D. Van Nostrand Co., Inc., New York, NY, and the “United States
published as D 2725 - 68 T. Last previous edition D 2725 - 70 (1980)‘2.
Pharmacopeia.”
2 Atmul Book of ASTM Slandards, Vol 1 I .O I I
6 Matheson C. P. grade, manufactured by Matheson Gas Products Inc., 30-T
3 Discontinued: see 1991 Annual Book o/ASTM Slandards, Vol 05.05.
Seaview Drive, Secaucus, NJ 07094, has been found satisfactory for this purpose.
4 A glass color ftlter, C. S. No. 3-66, manufactured by Corning Glass Works,
7 Eastman white label, manufactured by Eastman Chemical Products Inc., P.O.
Corning, NY 14830, has been found satisfactory for this purpose.
Box 431, Kingsport, TN 37662, has been found satisfactory for this purpose.
ASTM DE’725 87 m 0759530 0539459 668 -
a few drops of glacial acetic acid, sufficient to clear up the
solution.
6. Calibration
6.1 Place about 500 mL of water in a 1-L glass-stoppered
Erlenmeyer flask. Dissolve in the water 15 mL of gaseous
hydrogen sulfide (H,S), measured in a gas-tight syringe.
NOTE 1: Warning-H,S is extremely toxic. All handling of pure H,S
or gases containing H2S in concentrations above a few parts per million
should be carried out in a hood.
6.2 Pipet 25 mL of 0.01 N iodine solution into each of
two iodine flasks, add 2 mL of concentrated HCl, and cool in !
an ice bath. F‘ill a 500-mL volumetric flask to below the neck
with zinc acetate solution and pipet 10 mL of the H2S
solution into the flask and mix. Then pipet 50 mL of this
H2S solution into each of the iodine flasks and shake.
6.3 Back titrate each of the mixtures in the iodine flasks
with standard 0.01 N sodium thiosulfate solution to a pale
yellow, add 5 mL of starch solution, and continue the
titration to the disappearance of the blue color.
6.4 Bring the 500-mL volumetric flask to volume with
zinc acetate reagent, and mix. Of the resulting zinc sulfide
FIG. 1 Absorption Flask
solution, pipet into six absorption flasks, aliquots of 40, 25,
10, 5, 2, and 1 mL, and bring the last five to about 10 mL
acid (H,SOJ (2 + 1) in a brown bottle. If the solution that is
below the neck with zinc acetate solution. Cool these
made appears cloudy, then the diamine solution is too old
standard solutions to 5°C and develop the methylene blue
and should be discarded. Reorder new diamine reagent.’ color by pipetting 5 mL of diamine solution into each, Mix
Store made solution in a refrigerator that is between 4 and gently but completely, and cool again to 5°C. Then add 1 mL
7°C. Make a fresh solution every two weeks. of ferric chloride solution a
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