1、Designation: D1534 95 (Reapproved 2017)Standard Test Method forApproximate Acidity in Electrical Insulating Liquids byColor-Indicator Titration1This standard is issued under the fixed designation D1534; the number immediately following the designation indicates the year oforiginal adoption or, in th
2、e 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 describes the determination of theapproximate total acid value of use
3、d electrical insulatingliquids having viscosities less than 24 cSt at 40C. It is a simpleprocedure that can be applied in the field. Where a quantitativeneutralization value is required, use Test Method D664 or TestMethod D974. These test methods should be applied in thelaboratory.1.2 The values sta
4、ted 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 an
5、d health practices and determine the applica-bility of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standar
6、ds, 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 TitrationD974 Test Method for Acid and Base Number by Color-Indicator T
7、itrationD1193 Specification for Reagent Water3. Summary of Test Method3.1 To determine whether the acidity is greater or less thana specified arbitrary value, a fixed volume of liquid to be testedis added to a graduated cylinder, together with a small amountof indicator (phenolphthalein) and the app
8、ropriate quantity ofstandard potassium hydroxide solution. The mixture is shakenand allowed to separate. The color of the aqueous layer at thebottom of the container when testing mineral oils, or at the topwhen testing askarels, determines whether the acidity is lessthan or greater than the arbitrar
9、y value chosen.3.2 To determine the approximate total acidity, the proce-dure is the same as described in 3.1 except that the potassiumhydroxide solution is added in small increments until the colorof the aqueous layer, after shaking and settling, is a faint pink.The volume of standard potassium hyd
10、roxide solution useddetermines the approximate total acid value.4. Significance and Use4.1 The approximate acidity of used electrical insulatingoils is an estimate of the total acid value of the oil. As acidvalues increase, oil quality decreases. This is usually due tooxidation of the oil while in s
11、ervice. In general, acidicby-products produce increased dielectric loss, increasedcorrosivity, and may cause thermal difficulties attributable toinsoluble components called “sludge.” This test method isadapted to a specific volume of oil; total acid values of 0.05 to0.5 mg of potassium hydroxide per
12、 gram of oil is a range whichis functionally significant.5. Apparatus5.1 Graduated Cylinder, 50 mL, stoppered.5.2 Medicine Dropper, calibrated at 1-mL intervals.5.3 Calibrated Pipet, 1-mL capacity, calibrated to deliver0.05-mL increments.6. Reagents and Materials6.1 Purity of ReagentsUse reagent gra
13、de chemicals in alltests. Unless otherwise indicated, it is intended that all reagentsshall conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society, where1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids an
14、d Gases and is the direct responsibility of Subcom-mittee D27.06 on Chemical Test.Current edition approved June 1, 2017. Published June 2017. Originallyapproved in 1958. Last previous edition approved in 2008 as D1534 95(2008).DOI: 10.1520/D1534-95R17.2For referenced ASTM standards, visit the ASTM w
15、ebsite, 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United St
16、atesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to T
17、rade (TBT) Committee.1such specifications are available.3Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water sha
18、ll be understood to mean reagent water (see Note1) conforming to Specification D1193.NOTE 1Any grades of water listed in Specification D1193 are deemedsatisfactory for the purpose of this test method.6.3 Ethyl or Isopropyl Alchol, reagent grade.6.4 Phenolphthalein Indicator Solution (100 g/L)Dissolv
19、e10 g of phenolphthalein in 100 mL of denatured alcohol byslight warming.6.5 Potassium Hydroxide, Standard Solution (0.031 60.003 N)Prepare a 0.031 6 0.003 N solution of potassiumhydroxide (KOH) by dissolving solid KOH in a solution ofequal volumes of alcohol and water in accordance with themethod o
20、f preparation and standardization described in TestMethod D974 or Test Method D664, except for the solvent andthe normality.NOTE 2As applied to mineral oil, this normality is chosen to simplifythe calculation. The 20-mL sample weighs 17.6 g, assuming an averagespecific gravity of 0.88. With a 17.6-g
21、 sample, 10 mL of 0.031 N KOHsolution corresponds to an acid value of 1. The normality should bechecked from time to time in a laboratory. If it is outside the 60.003tolerance, due either to evaporation of solvent or precipitation of potas-sium carbonate (K2CO3) formed by reaction with carbon dioxid
22、e (CO2)from the atmosphere, it should be discarded.The specific gravity of commonly used askarels is 1.56, or approxi-mately 1.8 times that of mineral oil, and this difference must be recognizedin the calculation or equipment calibration, or both, as applied to askarels.7. Procedure7.1 Rinse the gra
23、duated cylinder first with denatured alcoholand then with a small amount of the liquid to be tested. Pour inthe test specimen to the 20-mL mark and add two drops ofindicator solution with a medicine dropper. Proceed in accor-dance with 7.2 or 7.3.7.2 To determine whether the acidity is greater or le
24、ss thana value specified by the user, add the appropriate volume ofKOH solution by dispensing from a calibrated pipet (forexample, 0.5 mL if the fixed figure is 0.05 mg KOH per gramof oil, as applied to oil). Shake vigorously for several seconds,allow to settle, and observe the aqueous layer. If it
25、is free ofpink, the acidity is greater than the specified value.7.3 To determine the approximate total acidity, add KOHsolution in increments of 0.5 mL until the color of the aqueouslayer, after shaking and settling, is a pale pink.8. Calculation8.1 For mineral oil, calculate the approximate total a
26、cidvalue, T, as follows:T 5 B 2 A!/10 (1)where:A = test specimen used, (20) mL,B = liquid in the cylinder at the conclusion of the test,mL, andBA = KOH solution added, mL.8.2 For askarel, calculate the approximate total acid value,T, as follows:T 5 B 2 A!/18 (2)NOTE 3Other concentrations of base may
27、 be used in the titration. Aless concentrated solution of KOH provides a greater volume of theaqueous layer. The calculations must then be modified to account for thedifference in the concentration of base.NOTE 4As an alternative, prepackaged field kits have been used.49. Report9.1 Report the follow
28、ing information:9.1.1 The approximate total acidity value, T, in mgKOH/gtest specimen.9.1.2 When possible, report the acidity as “greater than” or“less than” the value specified by the user.10. Precision and Bias10.1 This test method provides for an approximation of totalacidity, with a minimum dete
29、ction level of 0.005 mgKOH/gtest specimen. The total acidity is based on whether the acidityis greater or less than a user-specified value corresponding tothe addition of specific volumes of KOH solution. Because thistest method is only an approximation of total acidity, precisionand bias statements
30、 will not be developed.10.2 To determine quantitative acidity values, use TestMethod D664 or Test Method D974.11. Keywords11.1 acidity; color titration; insulating liquid; neutralizationnumber3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For
31、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 Convention, Inc. (USPC), Rockville,MD.4Field kits, available fr
32、om Gerin Co., 1109 Seventh Ave., Neptune, NJ 07753have been found satisfactory for this purpose.D1534 95 (2017)2ASTM 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 advis
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35、you feel that your comments have not received a fair hearing 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. Individu
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