1、Designation: D 1534 95 (Reapproved 2008)Standard Test Method forApproximate Acidity in Electrical Insulating Liquids byColor-Indicator Titration1This standard is issued under the fixed designation D 1534; the number immediately following the designation indicates the year oforiginal adoption or, in
2、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 describes the determination of theapproximate total acid value of u
3、sed 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 D 664 or TestMethod D 974. These test methods should be applied in thelaboratory.1.2 The values
4、 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 safet
5、y 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 974 Test Method for Acid and Base Number by Color-Indicator TitrationD 1193 Spe
6、cification 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 appropriate quantity
7、 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 arbitrary value chosen.3.
8、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 hydroxide solution u
9、seddetermines 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 service. In genera
10、l, acidicby-products produce increased dielectric loss, increased corro-sivity, and may cause thermal difficulties attributable to in-soluble 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 gram of oil
11、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 grade chemicals
12、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, wheresuch specifications are available.3Other grades may be used,provided it is first ascertained that the reagent is
13、of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gases and is the direct responsibility of Subcom-mittee D27.06 on Chemical Test.Current edition approv
14、ed May 1, 2008. Published June 2008. Originallyapproved in 1958. Last previous edition approved in 2002 as D 1534 95(2002)1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, r
15、efer to the standards Document Summary page onthe ASTM website.3Reagent 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 for LaboratoryChemicals,
16、 BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Purity of WaterUnless otherwise in
17、dicated, referencesto water shall be understood to mean reagent water (see Note1) conforming to Specification D 1193.NOTE 1Any grades of water listed in Specification D 1193 aredeemed satisfactory for the purpose of this test method.6.3 Ethyl or Isopropyl Alchol, reagent grade.6.4 Phenolphthalein In
18、dicator Solution (100 g/L)Dissolve 10 g of phenolphthalein in 100 mL of denaturedalcohol by slight 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 wa
19、ter in accordance with themethod of preparation and standardization described in TestMethod D 974 or Test Method D 664, except for the solventand the normality.NOTE 2As applied to mineral oil, this normality is chosen to simplifythe calculation. The 20-mL sample weighs 17.6 g, assuming an averagespe
20、cific gravity of 0.88. With a 17.6-g 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) f
21、ormed by reaction with carbon dioxide (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 as
22、karels.7. Procedure7.1 Rinse the graduated 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
23、whether the acidity is greater or less 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, a
24、nd observe the aqueous layer. If it 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 oi
25、l, calculate the approximate total acidvalue, 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)NO
26、TE 3Other concentrations of base may 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
27、used.49. Report9.1 Report the following 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
28、of totalacidity, with a minimum detection 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 a
29、cidity, precisionand bias statements will not be developed.10.2 To determine quantitative acidity values, use TestMethod D 664 or Test Method D 974.11. Keywords11.1 acidity; color titration; insulating liquid; neutralizationnumberASTM International takes no position respecting the validity of any pa
30、tent 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 rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revisio
31、n at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your com
32、ments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If 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 copyright
33、ed 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-mail); or through the ASTM website(www.astm.org).4Field kits, available from Gerin Co., 1109 Seventh Ave., Neptune, NJ 07753have been found satisfactory for this purpose.D 1534 95 (2008)2
