1、Designation: D7959 15Standard 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 parenthes
2、es 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 b
3、etween 0 mg L to0.3 mg L.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 s
4、tandard 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 sol
5、ution 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
6、 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 turb
7、ine 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
8、 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 St
9、ir 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 coat
10、ing 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 thereforeprodu
11、ce 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.NOTE 1Prior batches of Fisher Scientific pH 7 buffer solution, catalognumber SB108, have produced no reading on the
12、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 onP
13、etroleum 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 ad
14、junct 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/L Cl-) kn
15、own 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 technica
16、l committee,1which you may attend.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States18. 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 sh
17、ould 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 Vigorously shake the sample
18、 container by hand forapproximately 15 s before analysis.11.2 Add 3 L of the aviation turbine fuel test sample to a 4 Lbeaker by filling and emptying a 1 L graduated cylinder threetimes.11.3 Remove the remaining fuel from the sample container.11.4 Completely drain the sample container (discarding an
19、yresidual fuel) by means of one of the following methods.11.4.1 If the sample container has a spout and can beeffectively drained (see Fig. 1), drain upside down for 2 min,tilting and shaking occasionally to remove any residual fuel.11.4.2 If the sample container does not have a spout andcannot be e
20、ffectively drained, tilt the sample container to theside or to a corner so that any residual fuel collects beneath thesample container opening (see Fig. 2). Wait approximately2 min. Remove any residual fuel with a clean pipette. Wait anadditional approximate 2 min and repeat (the same pipette maybe
21、used).11.5 Add 5 mL pH 7 buffer solution by pipette to the nowempty sample container.11.6 Cap the sample container tightly and hand shakevigorously for approximately 1 min. Try to have the pH 7buffer solution contact all inside surfaces of the container. Theuse of a shaker table is not recommended s
22、ince the buffersolution will not contact all inside surfaces of the container.11.7 Transfer the contents to the 4 L beaker via one of thefollowing methods.11.7.1 If the sample container has a spout and can beeffectively drained, drain upside down for approximately 30 s,tilting and shaking occasional
23、ly to transfer any residual buffersolution.11.7.2 If the sample container does not have a spout andcannot be effectively drained, tilt the sample container to theside or to a corner so that the buffer solution collects beneaththe sample container opening. Tap the side or corner a fewtimes lightly on
24、 a benchtop to encourage the buffer solution tocollect. Wait approximately 30 s. Transfer the buffer solutionwith a clean, 20 mL (or larger) pipette. Wait an additionalapproximate 30 s and repeat to ensure all the buffer solution isdelivered to the 4 L beaker. Set the pipette aside for later use;do
25、not clean. Lay the pipette down horizontally with no contactto the tip so that any residual buffer solution is not lost.11.8 Add 20 mL iso-octane to the sample container with anew, clean pipette.11.9 Cap the sample container tightly and hand shakevigorously for approximately 1 min.11.10 Transfer the
26、 iso-octane rinse to the 4 L beaker bymeans of one of the following methods.11.10.1 If the sample container has a spout and can beeffectively drained, drain upside down for approximately 30 s,tilting and shaking occasionally to transfer any residual iso-octane.FIG. 1 Draining of Sample Container wit
27、h a SpoutFIG. 2 Draining of Sample Container with No SpoutD7959 15211.10.2 If the sample container does not have a spout andcannot be effectively drained, tilt the sample container to theside or to a corner so that the iso-octane collects beneath thesample container opening. Tap the side or corner a
28、 few timeslightly on a benchtop to encourage the iso-octane to collect.Wait approximately 30 s. Remove iso-octane with the pipette,previously set aside. Wait an additional approximate 30 s andrepeat to ensure all iso-octane is delivered to the 4 L beaker.NOTE 2Despite the iso-octane rinse, there wil
29、l most likely be buffersolution residue remaining within the pipette.11.11 Tape a Distillate Fuel Bar Chart to the beaker (see Fig.3). The chart, which is double-sided, should be taped so that theleft and right sides conform to and make contact with the 4 Lbeaker and so the bottom of the card is flu
30、sh with the stir platesurface. Add a magnetic stir bar to the 4 L beaker. Ensuring thestir bar is centered in the bottom of the beaker will helpminimize any splashing. Stir at a setting at which line 5 of theDistillate Fuel Bar Chart is no longer visible. Figs. 4 and 5illustrate inadequate and adequ
31、ate stirring, respectively. Stir for10 min.After 10 min, remove the 4 L beaker from the stir plateand remove the stir bar.11.12 Obtain a few millilitres of the extract (lower layer) bymeans of one of the following methods and place into asuitable container (an 8 dram vial is ideal). Removing someavi
32、ation turbine fuel with the extract will not impact testresults.11.12.1 Tilt beaker on its side, let settle for approximately15 min. Carefully and slowly decant approximately 2.5 L ofthe aviation turbine fuel. Swirl remaining material and tiltbeaker on its side for an additional approximate 2 min. O
33、btainextract by pipette. See Figs. 6-8.11.12.2 Let beaker settle for approximately 15 min, care-fully and slowly decant approximately 2.5 L of the aviationturbine fuel, swirl the remaining material then transfer to anappropriate sized separatory funnel, let settle an additional5 min, then drain extr
34、act.11.13 Add a chloride test strip to the extract and wait untilyellow, horizontal band at the top of the scale turns dark (seeFig. 9).12. Calculation or Interpretation of Results12.1 Read the test strip to the nearest 0.1 (the graduations onthe test strip are 0.2). Convert the test strip reading t
35、o mg/Lchloride (to the nearest whole number) for the extract using thescale on the test strip container.12.1.1 The operator may need to interpolate between scalereadings.12.2 Multiply this value by 0.0017 to determine chloridecontent in mg/L of the aviation turbine fuel.13. Report13.1 Report the fol
36、lowing information:13.1.1 Date of analysis.13.1.2 Operator.13.1.3 pH 7 buffer manufacturer, lot number, and use bydate.13.1.4 Chloride test strip lot number and use by date (forexample, Use By: 02/2013 Lot A3253).13.1.5 Chloride test strip result to the nearest 0.1 (forexample, 1.9).13.1.6 Chloride
37、concentration of the extract, mg/L, to thenearest whole number (for example, 50).13.1.7 Chloride concentration of the aviation turbine fuelsample to two decimal places (for example, 0.08 mg/L).13.1.8 Reference this test method.FIG. 3 Taping of Double-Sided Distillate Fuel Bar Chart to 4 LBeakerFIG.
38、4 Inadequate Stir Speed (that is, Bars Still Visible)D7959 15314. Precision and Bias14.1 RepeatabilityA ruggedness study was performed byanalyzing aviation turbine fuel samples additized with differentchloride concentrations. Dodecyltrimethylammonium chloride,CAS #112-00-5, was solubilized in methan
39、ol and added to eachindividual aviation turbine fuel sample by mechanical pipette.FIG. 5 Adequate Stir Speed (that is, Bars No Longer Visible)FIG. 6 Test Fuel Before DecantingFIG. 7 Test Fuel After DecantingD7959 154Ten aviation turbine fuel samples were prepared and analyzedat each of three differe
40、nt chloride concentrations. The calcu-lated average values and the repeatability are shown in Table 1.Acomplete precision study will be conducted and the results ofthis study will be used to update this section within five years.14.2 ReproducibilityTo be determined.14.3 BiasSince there is no accepte
41、d reference materialsuitable for determining the bias in this test method, bias hasnot been determined.15. Keywords15.1 aviation turbine fuel; chloride; cleanliness; contamina-tion; jet fuel; Jet A; Jet A-1; salt; seawaterFIG. 8 Close-Up of ExtractD7959 155APPENDIX(Nonmandatory Information)X1. ESTIM
42、ATION OF CHLORIDE CONCENTRATION WHEN LESS THAN A 3 L TEST SAMPLE IS AVAILABLEX1.1 In order to quantify very low chloride concentrations,this test method requires a relatively large sample size (that is,3 L). There may be a need to determine chloride concentrationwhen less than the required 3 L sampl
43、e size is available. In thiscase, the following calculations can be used to provide anestimate of chloride concentration. The result, however, shouldnot be reported according to this method and the precisioninformation above in Section 14 would not be applicable.Although testing has not been conduct
44、ed to confirm, precisionshould be proportional to sample size.X1.2 Example:X1.2.1 Sample size is 2500 mL.X1.2.2 Chloride test strip result of 1.9 equates to a chlorideconcentration of 50 mg/L.X1.2.3 5 mLextract(1L/1000 mL)(50 mg Cl-/1 Lextract)(1/2500 mL sample)(1000 mL/1 L) = 0.10 mg/L Cl-.FIG. 9 C
45、hloride Test StripTABLE 1 Precision InformationSample Replicates Average, mg/L rA 10 0.07 0.01B 10 0.14 0.07C 10 0.25 0.10D7959 156ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard
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