1、Designation: D5770 11 (Reapproved 2017)Standard Test Method forSemiquantitative Micro Determination of Acid Number ofLubricating Oils During Oxidation Testing1This standard is issued under the fixed designation D5770; the number immediately following the designation indicates the year oforiginal ado
2、ption 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 is a semiquantitative micro methodintended for monitor
3、ing the changes in acidic constituentsoccurring in lubricating oils during oxidation testing, when theacid number of such oils falls within the range from 0.02 mg to1.0 mg of potassium hydroxide per gram of sample. It isapplicable to such oils as turbine oils, hydraulic oils, and othercirculating oi
4、ls.NOTE 1This test method is a micro version of Test Method D974 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 D974 or D664. It shallnot be use
5、d to monitor oils in-service.1.3 The values stated in SI units are to be regarded as thestandard.1.3.1 ExceptionThe values given in parentheses are forinformation only.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of
6、 the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Deci
7、sion on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D664 Test Method for Acid Number of Petroleum Productsby Potentiometric Titration
8、D943 Test Method for Oxidation Characteristics of InhibitedMineral OilsD974 Test Method for Acid and Base Number by Color-Indicator TitrationD3339 Test Method for Acid Number of Petroleum Productsby Semi-Micro Color Indicator TitrationD4871 Guide for Universal Oxidation/Thermal StabilityTest Apparat
9、us3. Terminology3.1 Definitions:3.1.1 acid number, nthe quantity of a specified base,expressed in milligrams of potassium hydroxide per gram ofsample, required to titrate a sample in a specified solvent to aspecified endpoint using a specified detection system.3.1.1.1 DiscussionIn this test method,
10、the acid number iscalculated 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
11、be reported inmilligrams of 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 n
12、oted.4.2 A second 2.0 mL portion 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
13、sample is calculatedusing the 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.1This test method is under the jurisdiction of ASTM Committee D02 onPe
14、troleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.Current edition approved May 1, 2017. Published June 2017. Originallyapproved in 1995. Last previous edition approved in 2011 as D5770 11. DOI:10.1520/D577
15、0-11R17.2For 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.*A Summary of Changes section appears at the end of t
16、his standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopm
17、ent of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15. Significance and Use5.1 This test method provides a semiquantitative estimate ofthe acid number of lubricating oils obtained from laboratoryoxidation test
18、s using smaller amounts of sample than TestMethods D974, D664,orD3339. It has specific application inTest Method D943 and in Test Method D4871. This testmethod, therefore, provides a means of monitoring the relativeoxidation of lubricating oils by measuring changes in acidnumber, at different time i
19、ntervals and under various oxidizingtest conditions.5.2 Since this test method is semiquantitative, each labora-tory shall develop its own criteria for each oxidation testmethod for determining when to switch from this semiquanti-tative test method to a more precise test method for acidnumber.6. App
20、aratus6.1 Glass Beakers, 10 mL capacity, or glass vials, 4 dram or6 dram.6.2 Glass Syringe, 2 mL to 5 mL capacity. A 5 mL inter-changeable syringe with a 20 gage, 12 cm needle is satisfac-tory.6.3 Dropping Pipet, glass with rubber bulb, capable ofdelivering 35 drops to 40 drops of oil.7. Reagents7.1
21、 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-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades can be
22、used 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 SolutionAny stable, oil-soluble acid which will produce an acid number of approxi-mately 0.5 mg g KOH is acceptable. Thi
23、s solution shall bestandardized using Test Method D974 or D664. A solution of0.20 % by mass dodecenylsuccinic anhydride in HVI 250 baseoil or in an ISO 10-22 (60-100 SUS) oil has proven satisfac-tory.7.3 Alcoholic Potassium Hydroxide Standard Solution (0.1M)Prepare approximately 0.1 M solution by di
24、ssolving 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 reagent havebeen found to be satisfactory.) (WarningCorrosive.)(WarningPoisonous if ingested, alkaline, causes irritationp
25、roducing dermatitis.)7.4 Dodecylsuccinic Anhydride(WarningIrritating toeyes and skin.)7.5 p-Naphtholbenzein Indicator SolutionThep-naphtholbenzein must meet the specifications in AppendixX1 of Test Method D974. Prepare a solution containing 10 g ofp-naphtholbenzein/L in a 50:50 mixture of toluene:pr
26、opanol-2-ol. (WarningFlammable. Vapor harmful.)NOTE 2In a 1992 study, only Kodak, Fisher, and Baker (Mallinkrot)were found to meet the specifications. However, the Kodak brand is nolonger available. The Fisher Reagent Solution was the only commerciallyavailable solution to meet the specifications.7.
27、6 Propanol-2-ol (Isopropyl Alcohol)(WarningFlammable.)(WarningIt has been reported that, unless in-hibited against it, peroxides can form in propanol-2-ol and, asthe storage vessel or equipment such as a dispensing bottlebecome empty and approach dryness, an explosive mixture canoccur.)7.7 Titration
28、 SolutionMix 350 mL of toluene, 350 mL ofpropanol-2-ol, and 7 mL of the p-naphtholbenzein solution in a1 L plastic bottle. Add 15 mL of 0.1 M potassium hydroxidealcoholic solution and mix well. (WarningFlammable. Va-por harmful. Corrosive.)NOTE 3The strength of the titration solution depletes with t
29、ime 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 amount of the test oilfrom the oxidation test cell according to the procedure speci-fied in the oxidation test method.NOT
30、E 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 of the titrationsolution into a 10 mL beaker or vial.8.3 Using the dropping pipet, add the oil sample to thetitratio
31、n 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 titration complete when the orange color is stablefor a minimum of 10 s.8.5 Repeat 8.2 through 8.4 using the acid numbe
32、r 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 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 nu
33、mber reference solutionin 8.5,B = acid number of the acid number reference solution, and3Reagent 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
34、for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D5770 11 (2017)2C = number of drops of the oil sample (8.4).9.2 Report the result as follows:acid number, Test MethodD 5770! 5 re
35、sult! (2)10. Precision and Bias10.1 PrecisionThe precision of this test method wasdetermined by statistical examination of interlaboratory testresults over the acid number range from 0.06 to 1.1 mg KOH/gfor nine samples analyzed by eight laboratories.410.1.1 RepeatabilityThe difference between two t
36、estresults, 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 operation ofthe test method, exceed the following values only in one casein twenty:0.20 3acid number (3)10.1.2 Reproducibil
37、ityThe difference between two singleand independent results, obtained by different operators work-ing in different laboratories on identical test material, would inthe long run, in the normal and correct operation of the testmethod, exceed the following values only in one case intwenty:0.70 3acid nu
38、mber (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 indicator titration; oxidation test-ing; semiquantitativeASTM International takes no position respecting the validity of any pate
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42、 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 be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-ma
43、il); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1356.D5770 11 (2017)3
