1、Designation: D 5770 02 (Reapproved 2007)An American National StandardStandard Test Method forSemiquantitative Micro Determination of Acid Number ofLubricating Oils During Oxidation Testing1This standard is issued under the fixed designation D 5770; the number immediately following the designation in
2、dicates 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is a semiquantitative
3、micro methodintended for monitoring the changes in acidic constituentsoccurring in lubricating oils during oxidation testing, when theacid number of such oils falls within the range from 0.02 to 1.0mg of potassium hydroxide per gram of sample. It is applicableto such oils as turbine oils, hydraulic
4、oils, and other circulatingoils.NOTE 1This test method is a micro version of Test Method D 974 andit produces results similar to that method.1.2 This test method is designed for use where sample sizeis limited. It shall not be used as a replacement for higherprecision methods such as Test Methods D
5、974 or D 664.Itshall not be used to monitor oils in-service.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 its use. It is the
6、responsibility 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 664 Test Method forAcid Number of Petroleum Productsby Potentiometric TitrationD 943
7、Test Method for Oxidation Characteristics of Inhib-ited Mineral OilsD 974 Test Method for Acid and Base Number by Color-Indicator TitrationD 3339 Test Method for Acid Number of Petroleum Prod-ucts by Semi-Micro Color Indicator TitrationD 4871 Guide for Universal Oxidation/Thermal StabilityTest Appar
8、atus3. Terminology3.1 Definitions:3.1.1 acid number, nthe quantity of base, expressed inmilligrams of potassium hydroxide per gram of sample, that isrequired to titrate a sample dissolved in a specified solvent toa specified endpoint.3.1.1.1 DiscussionIn this test method, the acid number iscalculate
9、d from the number of drops required to produce achange in solution color from blue-green to orange, comparedto the number of drops required to produce an identical colorchange using a reference standard. Because this is a directcomparison method, the acid number value can be reported inmilligrams of
10、 potassium hydroxide per gram of sample.4. Summary of Test Method4.1 A 2.0-mL portion of the titration solution is titrated witha sample using a dropping pipet. The number of drops ofsample required to turn the blue-green titration solution to apersistent orange color is noted.4.2 A second 2.0-mL po
11、rtion of the titration solution istitrated with an acid number reference solution of known acidnumber. The number of drops of the reference solutionrequired to turn the blue-green titration solution to a persistentorange color is noted.4.3 The estimated acid number of the sample is calculatedusing t
12、he acid number of the reference solution and the ratio ofthe number of drops of the reference solution required to effectthe color change to the number of drops of the sample requiredfor the same change.5. Significance and Use5.1 This test method provides a semiquantitative estimate ofthe acid numbe
13、r of lubricating oils obtained from laboratoryoxidation tests using smaller amounts of sample than TestMethods D 974, D 664, or D 3339. It has specific application inTest Method D 943 and in Test Method D 4871. This test1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Pr
14、oducts and Lubricants and is the direct responsibility of SubcommitteeD02.06 on Analysis of Lubricants.Current edition approved May 1, 2007. Published June 2007. Originallyapproved in 1995. Last previous edition approved in 2002 as D 5770 02.2For referenced ASTM standards, visit the ASTM website, ww
15、w.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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.meth
16、od, therefore, provides a means of monitoring the relativeoxidation of lubricating oils by measuring changes in acidnumber, at different time intervals and under various oxidizingtest conditions.5.2 Since this test method is semiquantitative, each labora-tory shall develop its own criteria for each
17、oxidation testmethod for determining when to switch from this semiquanti-tative test method to a more precise test method for acidnumber.6. Apparatus6.1 Glass Beakers, 10-mL capacity, or glass vials, 4 or 6dram.6.2 Glass Syringe, 2-5 mLcapacity.A5-mLinterchangeablesyringe with a 20 gage, 12 cm needl
18、e is satisfactory.6.3 Dropping Pipet, glass with rubber bulb, capable ofdelivering 35 to 40 drops of oil.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless indicated otherwise, it is intended thatall reagents shall conform to the specifications of the Commit-t
19、ee 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 Acid Number Reference S
20、olutionAny stable, oil-soluble acid which will produce an acid number of approxi-mately 0.5 mg KOH/g is acceptable. This solution shall bestandardized using Test Method D 974 or D 664. A solution of0.20 % mass dodecenylsuccinic anhydride in HVI 250 base oilor in an ISO 10-22 (60-100 SUS) oil has pro
21、ven satisfactory.7.3 Alcoholic Potassium Hydroxide Standard Solution (0.1M)Prepare approximately 0.1 M solution by dissolving KOHin propanol-2-ol. Standardize against pure potassium acidphthalate in about 100 mL of water, using phenolphthalein todetect the end point. (Commercial grades of this reage
22、nt havebeen found to be satisfactory.) (WarningCorrosive.)(WarningPoisonous if ingested, alkaline, causes irritationproducing dermatitis.)7.4 Dodecylsuccinic Anhydride(WarningIrritating toeyes and skin.)7.5 p-Naphtholbenzein Indicator SolutionThep-naphtholbenzein must meet the specifications in Appe
23、ndixX1 of Test Method D 974. Prepare a solution containing 10 gof p-naphtholbenzein/L in a 50:50 mixture oftoluene:propanol-2-ol. (WarningFlammable. Vapor harm-ful.)NOTE 2In a 1992 study, only Kodak, Fisher, and Baker (Mallinkrot)were found to meet the specifications. However, the Kodak brand is nol
24、onger available. The Fisher Reagent Solution was the only commerciallyavailable solution to meet the specifications.7.6 Propanol-2-ol (Isopropyl Alcohol)(WarningFlammable.) (WarningIt has been reported that, unlessinhibited against it, peroxides can form in propanol-2-ol and, asthe storage vessel or
25、 equipment such as a dispensing bottlebecome empty and approach dryness, an explosive mixture canoccur.)7.7 Titration SolutionMix 350 mL of toluene, 350 mL ofpropanol-2-ol, and 7 mL of the p-naphtholbenzein solution ina 1-L plastic bottle. Add 15 mL of 0.1 M potassium hydroxidealcoholic solution and
26、 mix well. (WarningFlammable. Va-por harmful. Corrosive.)NOTE 3The strength of the titration solution depletes with time andshould be periodically replaced. Up to one month has been found to besatisfactory.7.8 Toluene(WarningFlammable. Vapor harmful.)8. Procedure8.1 SamplingWithdraw the minimal amou
27、nt of the test oilfrom the oxidation test cell according to the procedure speci-fied in the oxidation test method.NOTE 4As oxidized oils can change appreciably in storage, samplesshould be tested as soon as possible after removal from the oxidation testequipment.8.2 Using the syringe, measure 2.0 mL
28、 of the titrationsolution into a 10-mL beaker or vial.8.3 Using the dropping pipet, add the oil sample to thetitration solution one drop at a time, swirling constantly.8.4 Count the number of drops of oil sample required tochange the titration solution color from blue-green to orange.Consider the ti
29、tration complete when the orange color is stablefor a minimum of 10 s.8.5 Repeat 8.2 through 8.4 using the acid number referencesolution in place of the oil sample as the titrant of 2.0 mL oftitration solution, so that the final colors for the two beakersmatch.9. Calculation and Report9.1 Calculate
30、the acid number of the oil sample as follows:acid number, mg KOH/g 5A 3 BC(1)where:A = number of drops of the acid number reference solutionin 8.5,B = acid number of the acid number reference solution, andC = number of drops of the oil sample (8.4).3Reagent Chemicals, American Chemical Society Speci
31、fications , 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. Pharmacopeial Conve
32、ntion, Inc. (USPC), Rockville,MD.D 5770 02 (2007)29.2 Report the result as follows:acid number, Test Method D 5770! 5 result! (2)10. Precision and Bias10.1 PrecisionThe precision of this test method wasdetermined by statistical examination of interlaboratory testresults over the acid number range fr
33、om 0.06 to 1.1 mg KOH/gfor nine samples analyzed by eight laboratories.410.1.1 RepeatabilityThe difference between two test re-sults, obtained by the same operator with the same apparatusunder constant operating conditions on identical test material,would in the long run, in the normal and correct o
34、peration ofthe test method, exceed the following values only in one casein twenty:0.20 3 acid number (3)10.1.2 ReproducibilityThe difference between two singleand independent results, obtained by different operators work-ing in different laboratories on identical test material, would inthe long run,
35、 in the normal and correct operation of the testmethod, exceed the following values only in one case intwenty:0.70 3 acid number (4)10.2 BiasThe procedures in this test method have no biasbecause the acid number can be defined only in terms of thetest method.11. Keywords11.1 acid number; color indic
36、ator titration; oxidation test-ing; semiquantitativeASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rig
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39、 you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may
40、 be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D02-1356.D 5770 02 (2007)3
