ASTM D4468-85(2000)
(Test Method)Standard Test Method for Total Sulfur in Gaseous Fuels by Hydrogenolysis and Rateometric Colorimetry
Standard Test Method for Total Sulfur in Gaseous Fuels by Hydrogenolysis and Rateometric Colorimetry
SCOPE
1.1 This test method covers the determination of sulfur gaseous fuels in the range from 0.001 to 20 parts per million by volume (ppm/v).
1.2 This test method may be extended to higher concentration by dilution.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems 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. Specific precautionary statements are given in 6.7, 6.8, and 7.3.
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Designation:D4468–85(Reapproved2000)
Standard Test Method for
Total Sulfur in Gaseous Fuels by Hydrogenolysis and
Rateometric Colorimetry
This standard is issued under the fixed designation D4468; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope nation in finished products, such as propane, butane, ethane,
and ethylene.
1.1 This test method covers the determination of sulfur
gaseousfuelsintherangefrom0.001to20partspermillionby
5. Apparatus
volume (ppm/v).
5.1 Pyrolysis Furnace—A furnace that can provide an
1.2 This test method may be extended to higher concentra-
adjustabletemperatureof900to1300°Cinaquartzorceramic
tion by dilution.
tubeof5mmorlargertube(ID)isrequiredforpyrolysisofthe
1.3 This standard may involve hazardous materials, opera-
sample. (See Fig. 1.) The flow system is to be a fluorocarbon
tions, and equipment. This standard does not purport to
orothermaterialinerttoH Sandothersulfurcompounds.(See
address all of the safety concerns associated with its use. It is
Fig. 1.)
the responsibility of the user of this standard to establish
5.2 Rateometric H S Readout—Hydrogenolysis products
appropriate safety and health practices and determine the
contain H S in proportion to sulfur in the sample. The H S
2 2
applicability of regulatory limitations prior to use. Specific
concentration is determined by measuring rate of change of
precautionary statements are given in 6.7, 6.8, and 7.3.
reflectance of a tape impregnated with lead acetate caused by
2. Referenced Documents darkening when lead sulfide is formed. Rateometric electron-
ics, adapted to provide first derivative output, allows sufficient
2.1 ASTM Standards:
2 sensitivity to measure to 0.001 ppm/v. (See Fig. 2.)
D1193 Specification for Reagent Water
5.3 Recorder—A suitable chart recorder may be used for a
D1914 Practice for Conversion Units and Factors Relating
3 permanent record of analysis.
to Sampling and Analysis of Atmospheres
6. Reagents and Materials
3. Summary of Test Method
6.1 Purity of Chemicals—Reagent grade unless specified
3.1 The sample is introduced at a constant rate into a
otherwise.
flowing hydrogen stream in a hydrogenolysis apparatus. The
6.2 Purity of Water—Unless otherwise indicated, reference
sampleandhydrogenarepyrolyzedatatemperatureof1000°C
to water shall be understood to mean Type II, reagent grade
or above, to convert sulfur compounds to hydrogen sulfide
water, conforming to Specification D1193.
(H S). Readout is by the rateometric detection of the colori-
6.3 Sensing Tape—Lead acetate impregnated analytical
metricreactionofH Swithleadacetate.Unitsusedareppm/v,
quality filter paper shall be used.
which is equivalent to micromoles/mole.
6.4 AceticAcid (5%)—Mix1partbyvolumereagentgrade
4. Significance and Use
glacial acetic acid with 19 parts water to prepare 5% acetic
acid solution.
4.1 This test method can be used to determine specification,
6.5 Gastight Syringe—A gastight 0.1- and 0.5-mL syringe
or regulatory compliance to requirements, for total sulfur in
for preparing calibration standard. Volumetric measurement
gaseous fuels. In gas processing plants, sulfur can be a
accuracy of the syringe shall be 1% or better.
contaminantandmustberemovedbeforegasisintroducedinto
6.6 PistonCylinder—Usea10-Lacryliccylinderwithafree
gas pipelines. In petrochemical plants, sulfur is a poison for
moving piston and silicone rubber “O” ring lubricated with a
many catalysts and must be reduced to acceptable levels,
free-flowing silicone lubricant. This cylinder is used to
usually in the range from 0.01 to 1 ppm/v. This test method
prepare ppm/v calibration samples volumetrically.
may also be used as a quality-control tool for sulfur determi-
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous The apparatus described in 5.1, 5.2, 6.3, 6.5, and 6.6 is similar in specification
Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of to the equipment available from HoustonAtlas Inc., 22001 N. Park Dr., Kingwood,
Special Constituents of Gaseous Fuels. TX 77339–3804. For further information see U.S. Patent No. 3,756,781, C. L.
Current edition approved March 29, 1985. Published July 1985. Kimbell, inventor.
2 5
Annual Book of ASTM Standards, Vol 11.01. Dow Corning 200 silicone grease has been found to be satisfactory for this
Annual Book of ASTM Standards, Vol 11.03. application.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D4468
FIG. 1 Hydrogenolysis Flow Diagram
6.7 CarbonylSulfide(COS)—AlecturebottleofCOS,99% mL/min, except when the sample has thiophenic compounds
purity, with a needle valve connected to the lecture bottle thatrequire200mL/minofH flowforconversion.Makefinal
outlet. Connect 2 ft of tygon tubing to allow insertion of a temperatureadjustmentto1000615°Coraminimum1300°C
hypodermic syringe to withdraw pure COS while tubing is if the sample contains thiophenic sulfur compounds.
purged from the lecture bottle. Other sulfur compounds can be
7.3 Install sensing tape and turn H S readout analyzer on.
used with adequate odor control. If the sulfur compound has Use adequate safety precautions in handling lead acetate tape.
two sulfur atoms per molecule, reduce the volume by one half.
7.4 Adjust the zero of the analyzer indicator meter (and
(Warning—Work with COS should be done in a well-
recorder if used) to desired position with no flow. This should
ventilated area, or under a fume hood.)
be performed with span at maximum.
6.8 Hydrogen Gas—Use sulfur-free hydrogen of laboratory
7.5 Test hydrogen purity by turning on hydrogen flow and
grade. (Warning—Hydrogen has wide explosive limits when
noting any change in zero position after 5 min. If the reading
mixed with air. See 1.3 regarding precautions.)
is upscale from the zero set point by greater than 4%, then the
6.9 CarrierGasforCalibrationStandards—Usesulfur-free
hydrogen source should be suspect as not being sulfur free and
laboratorygradebottledgasofthesametypeorsimilardensity
should be changed.
asthegastobeanalyzedorcalibratetheflowmetertoestablish
7.6 If the change in the recorder zero is less than 4%, then
correct flow setting for an available carrier gas. Test, as in 7.5,
reset the recorder zero to the desired position while the
adding the carrier gas flow to the hydrogen flow.
hydrogenisflowing.Thisshouldbeperformedwiththespanat
6.10 Purge Gas—Sulfur-free purge gas, nitrogen, CO , or
2 maximum.
other inert gas. Commercial grade cylinder gas is satisfactory.
8. Standardization
7. Preparation of Apparatus
8.1 With hydrogen flow at 200 mL/min, advance tape to an
7.1 Turnonthefurnaceandallowtemperaturetostabilizeat
unexposed area and note baseline.
1000°C. If thiophenic sulfur could be present, use 1300°C
8.2 Prepare a reference standard as described in Section 9.
temperature setting.
Connect the reference sample to the pump and the pump to the
NOTE 1—Reduced operating temperature extends furnace life.
analyzer. When a stable reading is obtained, record this value
Thiopheniccompoundconversionincreasesfrom
...
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