ASTM_D_1744_-_13.pdf

Designation:D174413An American National StandardStandard Test Method forDetermination of Water in Liquid Petroleum Products byKarl Fischer Reagent1This standard is issued under the fixed designation D1744;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method covers the determination of water inthe concentration from 50 to 1000 mg/kg in liquid petroleumproducts.1.2 Values stated in SI units are to be regarded as thestandard.Inch-pound units are provided for information only.1.3 This standard does not purport to address all of thesafety problems,if any,associated with 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.For specificprecautionary statements see Section 7.2.Referenced Documents2.1 ASTM Standards:2D4057 Practice for Manual Sampling of Petroleum andPetroleum Products3.Summary of Test Method3.1 The material to be analyzed is titrated with standardKarl Fischer reagent to an electrometric end point.4.Significance and Use4.1 Knowledge of the water content of petroleum productscan be useful to predict quality and performance characteristicsof the product.5.Interferences5.1 Free alkali,oxidizing and reducing agents,mercaptans,certain basic nitrogenous substances,or other materials thatreact with iodine,interfere.One part per million of sulfur asmercaptan causes an error in the titration,equivalent toapproximately 0.2 mg/kg of water.6.Apparatus6.1 Assemble the apparatus as described in the Annex A1.(See Note 1.)NOTE1Any apparatus that will give equal or better precision isacceptable.7.Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades can beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean distilled water or water ofequal purity.The solvents used must have low-water content,for example,less than 500 mg/kg mass.7.3 Karl Fischer Reagent,Solution(Note 2),Stock(WarningToxic.)For each litre of solution,dissolve 85 6 1g of iodine in 270 6 2 mL of pyridine in a dry,glass-stopperedbottle.Add 670 6 2 mL of methanol(99.9%)(Note 3).Coolthe mixture in an ice bath to below 3.9C.Bubble gaseoussulfur dioxide(SO2)(Note 4)through concentrated sulfuricacid(H2SO4,rel dens 1.84)(see warning information below)into the cooled mixture.Continue the addition of SO2until thevolume is increased 50 6 1 mL.Alternatively,add 50 6 1 mLof freshly drawn liquid SO2in small increments to theprecooled mixture in an ice bath.Mix well and set aside for at1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.02 on Hydrocarbon Measurement for Custody Transfer(JointASTM-API).Current edition approved Dec.1,2013.Published December 2013.Originallyapproved in 1960.Last previous edition approved in 1992 as D1744 92,whichwas withdrawn in January 2000 and reinstated in December 2013.DOI:10.1520/D1743-13.2For 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 the standards Document Summary page onthe ASTM website.3Reagent 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 United States Pharmacopeiaand National Formulary,U.S.Pharmaceutical Convention,Inc.(USPC),Rockville,MD.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 least 12 h before using.(WarningPoison.Corrosive.Strongoxidizer.Contact with organic material can cause fire.Can befatal if swallowed.Liquid and vapor can cause severe burns.Harmful if inhaled.Contact with water liberates large amountsof heat.Spillage can cause fire.)NOTE2Commercially prepared Karl Fischer Reagent may be used.NOTE3If 99.9%methanol is not commercially available,it can beprepared by dissolving 24 g of magnesium metal turnings in 200 mL ofmethanol.Caution,the reaction is vigorous.When the reaction