1、Designation: D 2784 06An American National StandardStandard Test Method forSulfur in Liquefied Petroleum Gases (Oxy-Hydrogen Burneror Lamp)1This standard is issued under the fixed designation D 2784; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of total sulfurin liquefied petroleum gases c
3、ontaining more than 1 g/g.Specimens should not contain more than 100 g/g of halogens.1.2 To attain the quantitative detectability that the testmethod is capable of, stringent techniques must be employedand all possible sources of sulfur contamination must beeliminated. In particular, cleaning agents
4、, such as commonhousehold detergents which contain sulfates, should beavoided.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with
5、its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 156 Test Method for Saybolt Color of Petroleum Prod-ucts (Saybolt C
6、hromometer Method)D 1193 Specification for Reagent WaterD 1265 Practice for Sampling Liquefied Petroleum (LP)Gases, Manual MethodD 1266 Test Method for Sulfur in Petroleum Products(Lamp Method)D 1657 Test Method for Density or Relative Density ofLight Hydrocarbons by Pressure HydrometerE11 Specifica
7、tion for Wire Cloth and Sieves for TestingPurposes2.2 Energy Institute Standard:3IP 181 Sampling Petroleum Gases, Including LiquefiedPetroleum Gases3. Summary of Test Method3.1 The sample is burned in an oxy-hydrogen burner, or ina lamp in a closed system in a carbon dioxide-oxygenatmosphere. The la
8、tter is not recommended for trace quantitiesof sulfur due to the inordinately long combustion times needed.The oxides of sulfur are absorbed and oxidized to sulfuric acidin a hydrogen peroxide solution. The sulfate ions are thendetermined by either of the following finishes:3.1.1 Barium Perchlorate
9、TitrationThe sulfate is titratedwith barium perchlorate using a thorin-methylene blue mixedindicator.3.1.2 TurbidimetricThe sulfate is precipitated as bariumsulfate and the turbidity of a suspension of the precipitate ismeasured with a photometer.4. Significance and Use4.1 It is important to have th
10、e sulfur content of liquefiedpetroleum gases at low enough concentration to meet govern-ment regulations. The presence of sulfur can result in corrosionof metal surfaces. Sulfur can be poisonous to catalysts insubsequent processing.5. Apparatus5.1 Oxy-Hydrogen Combustion AssemblyThe two typeslisted
11、below are recommended. Any combustion apparatusgiving equivalent results, however, is satisfactory.5.1.1 Wickbold-Type Combustion Apparatus, as shown inFig. 1.5.1.2 Modified Beckman Burner-Type Apparatus,4,5asshown in Fig. 2. Each of the above types of apparatus shallconsist of three parts: atomizer
12、-burner, combustion chamber,and absorber with spray trap. A blowout safety port in the1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved Dec. 1, 20
13、06. Published January 2007. Originallyapproved in 1969. Last previous edition approved in 2003 as D 278498(2003)e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to t
14、he standards Document Summary page onthe ASTM website.3Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,U.K., http:/www.energyinst.org.uk.4The sole source of supply of the apparatus known to the committee at this timeis Scientific Glassblowing Co., P.O. Box 18353, Houston, TX 7
15、7023.5If you are aware of alternative suppliers, please provide this information toASTM International Headquarters. Your comments will receive careful consider-ation at a meeting of the responsible technical committee,1which you may attend.1*A Summary of Changes section appears at the end of this st
16、andard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Sbustion chamber is desirable. The remainder of the appa-ratus shall consist of a suitable support stand with the necessaryneedle valves and flow meters for precise control of oxygen,hyd
17、rogen, and vacuum.5.1.3 Safety ShieldA transparent shield shall be used toprotect the operator in the event an explosive mixture is formedin the combustion chamber.5.2 Apparatus for Lamp Combustion:5.2.1 Absorbers, Chimneys, and Spray Traps, as requiredare described in detail in Annex A3 of Test Met
18、hod D 1266.5.2.2 Manifold System, consisting of a vacuum manifoldwith regulating device, valves, etc. (Fig. 2 of Test MethodD 1266) and a dual manifold (burner and chimney) supplyinga gas mixture of approximately 70 % carbon dioxide (CO2) and30 % oxygen (O2) at regulated pressures. The gas mixture i
19、nthe chimney manifold shall be maintained at a nearly constantpressure of 1 to 2 cm of water and the burner manifold atapproximately 20 cm of water. A suitable arrangement isshown in Fig. 2 of Test Method D 1266 and described in A3.6of Annex A3 of Test Method D 1266, but any other similarsystem givi
20、ng equivalent results can be used.5.2.3 Blast Type Gas Burner, having dimensions given inFig. 3.5.3 Vacuum Source, having a capacity of at least 1200 L/h.If a vacuum pump is used, it should be protected by a suitabletrap.5.4 Corrosion-Resistant Metal Cylinder, 75-mLIt shall betested at a pressure of
21、 600 psig (4.14 MPa gage) and shall showno leaks when filled with air or nitrogen to this pressure andsubmerged in water. It shall be fitted with a needle valve forconnection to the burner assembly.5.5 Variable Transformer, 0120 V, 750-W.5.6 Carbon Dioxide Pressure RegulatorThis regulatorshould be o
22、f a type that eliminates the refrigeration difficultiesoccurring with the pressure reduction of carbon dioxide.5,66. Reagents and Materials6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifi
23、cations of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.7Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2
24、 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Types II or III of Specification D 1193. Water conforming tothe following specification is required. Sulfate-free deionizedwater prepared by percolation of water through a column ofm
25、ixed anion and cation exchange resins.NOTE 1A means for determining when to replace the exchange resinsshould be provided. Use of a simple electrical conductivity meter has beenfound satisfactory for this purpose.6.3 Standard Sulfate Solution (1 mL = 100 g S)Dilute6.24 6 0.01 mL of 1 N sulfuric acid
26、 (H2SO4) with water toexactly 1 L. Check the dilution by titration against standardNaOH solution of about the same normality and adjust theconcentration, if necessary, so that each millilitre of thissolution is equivalent to 100 g of sulfur.6.4 Hydrogen (WarningExtremely flammable), CarbonDioxide (W
27、arningGas may reduce oxygen available forbreathing), and Oxygen (WarningOxygen accelerates com-bustion), meeting the requirement in Note 12.6.5 Scavenger-RinseMix equal volumes of low-sulfuracetone and isopropanol.6.6 Hydrogen Peroxide Solution (1.5 %) (1 + 19)Mix 1volume of concentrated hydrogen pe
28、roxide (H2O2=30%)with 19 volumes of water. Store in a dark-colored, glass-stoppered bottle.6.7 Quality Control (QC) Sample(s), preferably are portionsof one or more liquefied petroleum gas materials or productstandards of known sulfur content that were not used in thegeneration of the instrument cal
29、ibration curve. These (QC)samples are to be used to check the validity of the testingprocess as described in Section 16. An ample supply of QC6The sole source of supply of the Victor Type SR 300 regulator known to thecommittee at this time is Victor Equipment Co., Controls Division, 2336 AuburnBlvd.
30、, Sacramento, CA 95821.7Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the U
31、nited States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Atomizer-burner2Sample tube3Combustion chamber4Three-way stopcock5Receiver6Spray trapFIG. 1 Flow Diagram of a Typical Oxy-Hydrogen CombustionApparatusD2784062sample material shall be available
32、for the intended period ofuse, and must be homogeneous and stable under the anticipatedstorage conditions.7. Sampling Test Specimens and Test Units7.1 Obtain the test unit in a container by the methodconforming to the recommendations in Practice D 1265,orIPMethod 181.7.2 Evacuate a clean, dry 75-mL
33、cylinder and weigh to thenearest 0.05 g. Connect the container to the inverted supplycylinder and introduce 24 to 45 g of the liquefied gas, takingcare that the container does not become full of liquid. Toprevent this, bleed off a small amount of the liquid phase of thematerial after filling but bef
34、ore reweighing. Reweigh thecylinder to 0.05 g.NOTE 2The 75-mL, corrosion-resistant metal vessel can be cleaned asfollows: Remove the needle valve. Wash the interior of the vessel andvalve, first with a sulfur-free hydrocarbon, such as n-pentane, and thenwash with acetone. Dry the interior of the ves
35、sel with clean compressedair and rinse it with HCl (1 + 10). Rinse the interior with water until thewash water is neutral to a pH test paper. Wash the vessel with acetone andallow to drain at least 10 min. Dry the vessel with a stream of clean,compressed air and reassemble.NOTE 3The corresponding li
36、quid petroleum gas sample density of thematerial being analyzed by this test method for sulfur will ultimatelydetermine the maximum weight that can be introduced into the 75-mLcylinder without becoming full of liquid. This maximum weight valueneeds to be compared to the sample sizes in Table 1 neede
37、d for thecorresponding finishes and expected sulfur concentrations indicated fordetermining the appropriate sample weight that needs to be introducedinto the cylinder in 7.2. As an example, if the sample density is 0.6 g/mLat room temperature, and if the weight of the liquefied petroleum gas ismaint
38、ained below 45 g in a 75-mL container, the container cannot becomefull of liquid at room temperature.8. Procedure for Combustion of Sample8.1 Connect the sample cylinder with stainless steel tubingto the gas expansion valve. Attach to this another section ofstainless steel tubing which runs to the v
39、icinity of the burner.Make the final connection to the burner with sulfur-free rubbertubing. Wrap the expansion valve with heating tape andconnect this to a variable transformer. Insert a thermometerbetween the heating tape and expansion valve so that thethermometer bulb is in contact with the valve
40、 body. See Fig. 4.8.2 Turn on the variable transformer and allow the expan-sion valve to reach 43C (110F). Alternatively the expansionvalve may be placed in a suitable metal beaker and coveredwith water maintained at 110F.8.3 Oxy-Hydrogen CombustionAssemble the apparatusaccording to the manufacturer
41、s directions (see also 14.1). Addto the absorber 25 mL of the hydrogen peroxide solution.(WarningBefore attempting subsequent operations, the op-erator should (1) be aware of the various hazards that can existthrough the improper use of hydrogen as a fuel, and (2) havethe safety shield in place.)8.3
42、.1 Light the burner and insert into the combustionchamber. If necessary, readjust gas flows. Open the bottomvalve of the sample cylinder. Slowly open the expansion valveuntil an optimum burning rate is achieved.8.4 Lamp CombustionAdd to the absorber 25 mL ofhydrogen peroxide solution. Assemble the c
43、himney, absorber,and spray trap and connect to the CO2-O2and vacuummanifold. Make the necessary vacuum adjustments (see 5.1 ofTest Method D 1266). Set up a control blank absorber as in 5.3of Test Method D 1266.8.4.1 Open the bottom valve of the sample cylinder. Slowlycrack the gas expansion valve. L
44、ight the burner with an alcohollamp, and insert the burner into the combustion chamber(chimney).FIG. 2 Trace Sulfur Apparatus Flow DiagramAll dimensions in millimetresFIG. 3 Blast-Type Gas BurnerD27840638.5 Burn a quantity of sample in accordance with Table 1.NOTE 4In burning materials with sulfur c
45、oncentrations greater than50 g/g, restrict sample sizes to give quantities that will not contain morethan 250 g of sulfur for the turbidimetric finish or more than 150 g forthe barium perchlorate finish. Alternatively, aliquots of the absorbersolutions which do not contain more than these maximums c
46、an be used.NOTE 5Minor adjustment of the gas flow rates can be necessary tomaintain those recommended by the manufacturer.8.6 After a sufficient quantity of sample has been burned,turn the bottom valve of the cylinder off. Allow the remaininggas in the tubing and gas expansion valve to burn itself o
47、ut.Turn the heat off on the gas expansion valve. Disconnect thetubing from the sample cylinder and reweigh the samplecylinder to the nearest 0.05 g. Leave the absorber solution inthe assembled lamp unit. The same absorber solution will beused for the scavenger-rinse burning. Allow the expansionvalve
48、 to cool to ambient temperature.8.7 If the oxy-hydrogen burner permits, flush the tubing andvalve with 10 mL of scavenger-rinse and burn without discon-necting the tubing. Otherwise disconnect the tubing and burn inthe normal liquid mode. For the lamp burning collect therinsings in a standard lamp s
49、ulfur (see Test Method D 1266)flask. Insert a standard burner equipped with a wick into theflask and carry out the combustion as described in Section 7 ofTest Method D 1266.8.8 For the oxy-hydrogen burners, when all of the rinsingsare consumed, shut down the burner as recommended by themanufacturer.8.9 After the rinsings have been burned in the lamp, removeit, turn off the CO2-O2supply, and turn off the vacuum pump.8.10 For oxy-hydrogen blank determinations burn a hydro-carbon stock with a very low or nondetectable sulfur content.Make
