ASTM D2784-98(2003)e1
(Test Method)Standard Test Method for Sulfur in Liquefied Petroleum Gases (Oxy-Hydrogen Burner or Lamp)
Standard Test Method for Sulfur in Liquefied Petroleum Gases (Oxy-Hydrogen Burner or Lamp)
SCOPE
1.1 This test method covers the determination of total sulfur in liquefied petroleum gases containing more than 1 μg/g. Specimens should not contain more than 100 μg/g of halogens.
1.2 To attain the quantitative detectability that the method is capable of, stringent techniques must be employed and all possible sources of sulfur contamination must be eliminated. In particular, cleaning agents, such as common household detergents which contain sulfates, should be avoided.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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 and health practices and determine the applicability of regulatory limitations prior to use.
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An American National Standard
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Designation: D 2784 – 98 (Reapproved 2003)
Standard Test Method for
Sulfur in Liquefied Petroleum Gases (Oxy-Hydrogen Burner
or Lamp)
This standard is issued under the fixed designation D 2784; 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.
e NOTE—Warning notes were editorially moved into the standard text in July 2003.
1. Scope 2.2 Institute of Petroleum Standard:
IP 181 Sampling Petroleum Gases, Including Liquefied
1.1 This test method covers the determination of total sulfur
Petroleum Gases
in liquefied petroleum gases containing more than 1 µg/g.
Specimens should not contain more than 100 µg/g of halogens.
3. Summary of Test Method
1.2 To attain the quantitative detectability that the method is
3.1 The sample is burned in an oxy-hydrogen burner, or in
capable of, stringent techniques must be employed and all
a lamp in a closed system in a carbon dioxide-oxygen
possiblesourcesofsulfurcontaminationmustbeeliminated.In
atmosphere. The latter is not recommended for trace quantities
particular, cleaning agents, such as common household deter-
ofsulfurduetotheinordinatelylongcombustiontimesneeded.
gents which contain sulfates, should be avoided.
The oxides of sulfur are absorbed and oxidized to sulfuric acid
1.3 The values stated in SI units are to be regarded as the
in a hydrogen peroxide solution. The sulfate ions are then
standard. The values given in parentheses are for information
determined by either of the following finishes:
only.
3.1.1 Barium Perchlorate Titration—The sulfate is titrated
1.4 This standard does not purport to address all of the
with barium perchlorate using a thorin-methylene blue mixed
safety concerns, if any, associated with its use. It is the
indicator.
responsibility of the user of this standard to establish appro-
3.1.2 Turbidimetric—The sulfate is precipitated as barium
priate safety and health practices and determine the applica-
sulfate and the turbidity of a suspension of the precipitate is
bility of regulatory limitations prior to use.
measured with a photometer.
2. Referenced Documents
4. Significance and Use
2.1 ASTM Standards:
4.1 It is important to have the sulfur content of liquefied
D 156 Test Method for Saybolt Color of Petroleum Prod-
2 petroleum gases at low enough concentration to meet govern-
ucts (Saybolt Chromometer Method)
3 ment regulations.Thepresenceofsulfur canresultincorrosion
D 1193 Specification for Reagent Water
of metal surfaces. Sulfur can be poisonous to catalysts in
D 1265 Practice for Sampling Liquefied Petroleum (LP)
2 subsequent processing.
Gases (Manual Method)
D 1266 Test Method for Sulfur in Petroleum Products
5. Apparatus
(Lamp Method)
5.1 Oxy-Hydrogen Combustion Assembly— The two types
D 1657 Test Method for Density or Relative Density of
2 listed below are recommended. Any combustion apparatus
Light Hydrocarbons by Pressure Hydrometer
giving equivalent results, however, is satisfactory.
E 11 Specification for Wire Cloth and Sieves for Testing
4 5.1.1 Wickbold-Type Combustion Apparatus, as shown in
Purposes
Fig. 1.
,
6 7
5.1.2 Modified Beckman Burner-Type Apparatus, as
shown in Fig. 2. Each of the above types of apparatus shall
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.03 on Elemental Analysis.
Current edition approved May 10, 2003. Published July 2003. Originally Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
approved in 1969. Last previous edition approved in 1998 as D 2784–98. 4th Floor, New York, NY 10036.
2 6
Annual Book of ASTM Standards, Vol 05.01. The sole source of supply of the apparatus known to the committee at this time
Annual Book of ASTM Standards, Vol 11.01. is Scientific Glassblowing Co., P.O. Box 18353, Houston, TX 77023.
4 7
Annual Book of ASTM Standards, Vol 14.02. If you are aware of alternative suppliers, please provide this information to
ASTM International Headquarters. Your comments will receive careful consider-
ation at a meeting of the responsible technical committee , which you may attend.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D 2784 – 98 (2003)
5.4 Corrosion-Resistant Metal Cylinder,75-mL—Itshallbe
testedatapressureof600psig(4.14MPagage)andshallshow
no leaks when filled with air or nitrogen to this pressure and
submerged in water. It shall be fitted with a needle valve for
connection to the burner assembly.
5.5 Variable Transformer, 0–120 V, 750-W.
5.6 Carbon Dioxide Pressure Regulator— This regulator
should be of a type that eliminates the refrigeration difficulties
7,8
occurring with the pressure reduction of carbon dioxide.
6. Reagents and Materials
6.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit-
tee onAnalytical Reagents of theAmerican Chemical Society,
where such specifications are available. Other grades may be
used, provided it is first ascertained that the reagent is of
sufficiently high purity to permit its use without lessening the
accuracy of the determination.
6.2 Purity of Water—Unless otherwise indicated, references
to water shall be understood to mean reagent water as defined
byTypesIIorIIIofSpecificationD 1193.Waterconformingto
the following specification is required. Sulfate-free deionized
1—Atomizer-burner
water prepared by percolation of water through a column of
2—Sample tube
3—Combustion chamber mixed anion and cation exchange resins.
4—Three-way stopcock
NOTE 1—Ameans for determining when to replace the exchange resins
5—Receiver
6—Spray trap shouldbeprovided.Useofasimpleelectricalconductivitymeterhasbeen
found satisfactory for this purpose.
FIG. 1 Flow Diagram of a Typical Oxy-Hydrogen Combustion
Apparatus
6.3 Standard Sulfate Solution (1 mL = 100 µg S)—Dilute
6.24 6 0.01 mL of 1 N sulfuric acid (H SO ) with water to
2 4
exactly 1 L. Check the dilution by titration against standard
consist of three parts: atomizer-burner, combustion chamber,
NaOH solution of about the same normality and adjust the
and absorber with spray trap. A blowout safety port in the
concentration, if necessary, so that each millilitre of this
combustion chamber is desirable. The remainder of the appa-
solution is equivalent to 100 µg of sulfur.
ratusshallconsistofasuitablesupportstandwiththenecessary
6.4 Hydrogen (Warning—Extremely flammable), Carbon
needle valves and flow meters for precise control of oxygen,
Dioxide (Warning—Gas may reduce oxygen available for
hydrogen, and vacuum.
breathing), and Oxygen (Warning—Oxygen accelerates com-
5.1.3 Safety Shield—A transparent shield shall be used to
bustion), meeting the requirement in Note 12.
protecttheoperatorintheeventanexplosivemixtureisformed
6.5 Scavenger-Rinse—Mix equal volumes of low-sulfur
in the combustion chamber.
acetone and isopropanol.
5.2 Apparatus for Lamp Combustion:
6.6 Hydrogen Peroxide Solution (1.5 %) (1 + 19) —Mix 1
5.2.1 Absorbers, Chimneys, and Spray Traps, as required
volume of concentrated hydrogen peroxide (H O =30%)
2 2
are described in detail in Annex A3 of Test Method D 1266.
with 19 volumes of water. Store in a dark-colored, glass-
5.2.2 Manifold System, consisting of a vacuum manifold
stoppered bottle.
with regulating device, valves, etc. (Fig. 2 of Test Method
6.7 Quality Control (QC) Sample(s), preferably are portions
D 1266) and a dual manifold (burner and chimney) supplying
of one or more liquefied petroleum gas materials or product
agasmixtureofapproximately70 %carbondioxide(CO )and
standards of known sulfur content that were not used in the
30 % oxygen (O ) at regulated pressures. The gas mixture in
generation of the instrument calibration curve. These (QC)
the chimney manifold shall be maintained at a nearly constant
samples are to be used to check the validity of the testing
pressure of 1 to 2 cm of water and the burner manifold at
approximately 20 cm of water. A suitable arrangement is
shown in Fig. 2 of Test Method D 1266 and described inA3.6
The sole source of supply of the Victor Type SR 300 regulator known to the
of Annex A3 of Test Method D 1266, but any other similar
committee at this time is Victor Equipment Co., Controls Division, 2336 Auburn
system giving equivalent results can be used.
Blvd., Sacramento, CA 95821.
5.2.3 Blast Type Gas Burner, having dimensions given in
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Fig. 3.
listed by the American Chemical Society, see Annual Standards for Laboratory
5.3 Vacuum Source, having a capacity of at least 1200 L/h.
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
If a vacuum pump is used, it should be protected by a suitable
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
trap. MD.
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D 2784 – 98 (2003)
FIG. 2 Trace Sulfur Apparatus Flow Diagram
NOTE 3—If the weight of liquefied petroleum gas is maintained below
45 g in a 75-mL container, the container cannot become full of liquid at
room temperature.
8. Procedure for Combustion of Sample
8.1 Connect the sample cylinder with stainless steel tubing
to the gas expansion valve. Attach to this another section of
stainless steel tubing which runs to the vicinity of the burner.
Make the final connection to the burner with sulfur-free rubber
tubing. Wrap the expansion valve with heating tape and
connect this to a variable transformer. Insert a thermometer
between the heating tape and expansion valve so that the
thermometer bulb is in contact with the valve body. See Fig. 4.
8.2 Turn on the variable transformer and allow the expan-
sion valve to reach 43°C (110°F). Alternatively the expansion
valve may be placed in a suitable metal beaker and covered
with water maintained at 110°F.
All dimensions in millimetres
FIG. 3 Blast-Type Gas Burner 8.3 Oxy-Hydrogen Combustion—Assemble the apparatus
according to the manufacturer’s directions (see also 14.1).Add
to the absorber 25 mL of the hydrogen peroxide solution.
(Warning—Before attempting subsequent operations, the op-
process as described in Section 16 An ample supply of QC
erator should (1) be aware of the various hazards that can exist
sample material shall be available for the intended period of
through the improper use of hydrogen as a fuel, and (2) have
use,andmustbehomogeneousandstableundertheanticipated
the safety shield in place.)
storage conditions.
8.3.1 Light the burner and insert into the combustion
chamber. If necessary, readjust gas flows. Open the bottom
7. Sampling Test Specimens and Test Units
valve of the sample cylinder. Slowly open the expansion valve
7.1 Obtain the test unit in a container by the method
until an optimum burning rate is achieved.
conforming to the recommendations in Practice D 1265, or IP
8.4 Lamp Combustion—Add to the absorber 25 mL of
Method 181.
hydrogen peroxide solution. Assemble the chimney, absorber,
7.2 Evacuate a clean, dry 75-mL cylinder and weigh to the
and spray trap and connect to the CO -O and vacuum
2 2
nearest 0.05 g. Connect the container to the inverted supply
manifold. Make the necessary vacuum adjustments (see 5.1 of
cylinder and introduce 24 to 40 g of the liquefied gas, taking
Test Method D 1266). Set up a control blank absorber as in 5.3
care that the container does not become full of liquid. To
of Test Method D 1266.
prevent this, bleed off a small amount of the liquid phase of the
8.4.1 Open the bottom valve of the sample cylinder. Slowly
material after filling but before reweighing. Reweigh the
crackthegasexpansionvalve.Lighttheburnerwithanalcohol
cylinder to 0.05 g.
lamp, and insert the burner into the combustion chamber
NOTE 2—The75-mL,corrosion-resistantmetalvesselcanbecleanedas
(chimney).
follows: Remove the needle valve. Wash the interior of the vessel and
8.5 Burn a quantity of sample in accordance with Table 1.
valve, first with a sulfur-free hydrocarbon, such as n-pentane, and then
wash with acetone. Dry the interior of the vessel with clean compressed NOTE 4—In burning materials with sulfur concentrations greater than
air and rinse it with HCl (1 + 10). Rinse the interior with water until the 50 µg/g, restrict sample sizes to give quantities that will not contain more
wash water is neutral to a pH test paper.Wash the vessel with acetone and than 250 µg of sulfur for the turbidimetric finish or more than 150 µg for
allow to drain at least 10 min. Dry the vessel with a stream of clean, the barium perchlorate finish. Alternatively, aliquots of the absorber
compressed air and reassemble. solutions which do not contain more than these maximums can be used.
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D 2784 – 98 (2003)
FIG. 4 Burner Assembly for LPG
TABLE 1 Sample Sizes
the sample. Likewise subtract any sulfur obtained in the lamp
Sample Size, g combustion blank from the total figure.
Sulfur Content, ppm
Turbidimetric Finish Barium Perchlorate Finish
8.11 Disconnect the spray trap from the vacuum line and
1to5 45 30
thoroughly rinse the spray trap and chimney with about 35 mL
5to10 20 10
10 to 50 5 3
of distilled water, collecting the rinsings in the absorber. It is
important that any materials clinging to these parts be trans-
ferred to the absorber to avoid low values for sulfur content.
NOTE 5—Minor adjustment of the gas flow rates can be necessary to
BARIUM PERCHLORATE TITRATION FINISH
maintain those recommended by the manufacturer.
8.6 After a sufficient quantity of sample has been burned,
9. Reagents
turn the bottom valve of the cylinder off. Allow the remaining
9.1 Ion-Free Water—Distill deionized water and store in
gas in the tubing and gas expansion valve to burn itself out.
tightly capped, high-density polyethylene bottles.
Turn the heat off on the gas expansion valve. Disconnect the
9.2 HydrochloricAcid,StandardAlcoholic (0.1M)—Dilute
tubing from the sample cylinder and reweigh the sample
20 mL of aqueous 0.5 M HCl with 80 mL of isopropanol.
cylinder to the nearest 0.05 g. Leave the absorber solution in
9.3 Inhibited Thorin-Methylene Blue Mixed Indicator
the assembled lamp unit. The same absorber solution will be
Solution—The indicator is made up as two solutions and these
used for the scavenger-rinse burning. Allow the expansion
mi
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