ASTM_D_7959_-_15.pdf

Designation:D795915Standard Test Method forChloride Content Determination1This standard is issued under the fixed designation D7959;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.1.Scope1.1 This test method covers a rapid means of determiningchloride content of aviation turbine fuel.This methodology isapplicable for chloride concentrations between 0 mg L to0.3 mgL.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,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.2.Referenced Documents2.1 ASTM Adjuncts:Distillate Fuel Bar Chart23.Summary of Test Method3.1 A 3 L sample of aviation turbine fuel is extracted withpH 7 buffer solution by a magnetic stir plate and stir bar.Thechloride in the aviation turbine fuel sample transfers to thebuffer solution.A portion of the aqueous extract solution isthen removed and analyzed with a chloride test strip.Silverions within the test strip combine with chloride ions in theextract as it is drawn up by capillary action to form a whitecolumn of silver chloride.The chloride concentration of theextract,determined by the height of the column,is then relatedback to the chloride content of the aviation turbine fuel sample.4.Significance and Use4.1 Chloride present in aviation turbine fuel can originatefrom refinery salt drier carryover or possibly from seawatercontamination(for example,product transferred by barge).Elevated chloride levels have caused corrosive and abrasivewear of aircraft fuel control systems leading to engine failure.35.Interferences5.1 Some pH 7 buffer solution can contain trace levels ofchloride compounds and therefore produce a false positivereading on the chloride test strip.Prior to using a new batch ofpH 7 buffer solution,a sample should be confirmed to produceno reading on the chloride test strip.6.Apparatus6.1 Magnetic Stir Plate and Stir BarThe magnetic stirplate shall be capable of producing the stirring energy de-scribed in Section 11.11.A magnetic stir bar in the form of across or“starburst”approximately 32 mm by 32 mm hasproven to be more stable than the traditional bar shape.The stirbar shall have a chemically inert coating such as polytetrafluo-roethylene(PTFE).6.2 Distillate Fuel Bar Chart.27.Reagents and Materials7.1 Iso-octane(2,2,4trimethylpentane,CAS#540-84-1)Minimum ACS reagent grade purity.7.2 pH 7 Buffer SolutionSome pH 7 buffer solution cancontain trace levels of chloride compounds and thereforeproduce a false positive reading on the chloride test strip.Priorto using a new batch of pH 7 buffer solution,a sample shouldbe confirmed to produce no reading on the chloride test strip.NOTE1Prior batches of Fisher Scientific pH 7 buffer solution,catalognumber SB108,have produced no reading on the chloride test strips.7.3 Chloride Test Strips4The conversion of the dimen-sionless test strip value to chloride concentration in mg/Lfound on the test strip container varies slightly from one lot ofchloride test strips to the next.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.J0.05 on Fuel Cleanliness.Current edition approved March 15,2015.Published April 2015.DOI:10.1520/D7959-15.2Available from ASTM International Headquarters.Order Adjunct No.ADJD417601.Original adjunct produced in 1991.3Guidelines for Sodium Chloride Contamination Troubleshooting and Decon-tamination of Airframe and Engine Fuel Systems,International Air TransportAssociation,2nd Ed.,February 1998,pg.1.4The sole source of supply of the apparatus(Hach Quantab Low Range(30-600 mg/LCl-)known to the committee at this time is Hach Company,P.O.Box389,Loveland,Colorado 80539-0389,http:/.If you are aware ofalternative suppliers,please provide this information to ASTM InternationalHeadquarters.Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 8.Hazards8.1 If a combination heater and stir plate is to be used,ensure the heater is off.9.Sampling,Test Specimens,and Test Units9.1 The sample should be obtained for testing in either a1 gal or 5 L container.9.2 Collect a sample of at least 3 L.10.Preparation of Apparatus10.1 Unless otherwise stated,all glassware should becleaned prior to use.No special cleaning or rinsing procedureis required.11.Procedure11.1 Vigorous