ASTM D4739-2011(2017) Standard Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration《采用盐酸电位滴定法测定碱值的标准试验方法》.pdf

《ASTM D4739-2011(2017) Standard Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration《采用盐酸电位滴定法测定碱值的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM D4739-2011(2017) Standard Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration《采用盐酸电位滴定法测定碱值的标准试验方法》.pdf（8页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D4739 11 (Reapproved 2017)Standard Test Method forBase Number Determination by Potentiometric HydrochloricAcid Titration1This standard is issued under the fixed designation D4739; the number immediately following the designation indicates the year oforiginal adoption or, in the case of

2、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.INTRODUCTIONCurrently, there are two ASTM test methods under the jurisdiction of Committee D02 used fordeter

3、mining base number by potentiometric titration: Test Method D2896 and Test Method D4739.They are both used throughout the petroleum industry. Test Method D2896 is for new oils and is usedin setting specifications since it is more accurate than Test Method D4739. Test Method D4739 shallbe used exclus

4、ively for the purpose of tracking base number loss as an oil proceeds in service. In manycases, the test methods will provide different results. Some comparisons are given in the Scope andthe Significance and Use sections of this test method to distinguish between the two standards and toprovide gui

5、dance to users.1. Scope1.1 This test method covers a procedure for the determina-tion of basic constituents in petroleum products and new andused lubricants. This test method resolves these constituentsinto groups having weak-base and strong-base ionizationproperties, provided the dissociation const

6、ants of the morestrongly basic compounds are at least 1000 times than that ofthe next weaker groups. This test method covers base numbersup to 250.1.2 In new and used lubricants, the constituents that can beconsidered to have basic properties are primarily organic andinorganic bases, including amino

7、 compounds. This test methoduses hydrochloric acid as the titrant, whereas Test MethodD2896 uses perchloric acid as the titrant. This test method mayor may not titrate these weak bases and, if so, it will titratethem to a lesser degree of completion; some additives such asinhibitors or detergents ma

8、y show basic characteristics.1.3 When testing used engine lubricants, it should berecognized that certain weak bases are the result of the servicerather than having been built into the oil. This test method canbe used to indicate relative changes that occur in oil during useunder oxidizing or other

9、service conditions regardless of thecolor or other properties of the resulting oil. The valuesobtained, however, are intended to be compared with the othervalues obtained by this test method only; base numbersobtained by this test method are not intended to be equal tovalues by other test methods. A

10、lthough the analysis is madeunder closely specified conditions, this test method is notintended to, and does not, result in reported basic propertiesthat can be used under all service conditions to predictperformance of an oil; for example, no overall relationship isknown between bearing corrosion o

11、r the control of corrosivewear in the engine and base number.1.4 This test method was developed as an alternative for theformer base number portion of Test Method D664 (lastpublished in Test Method D664 81).1.4.1 Colorimetric test methods for base number are TestMethod D974, IP 139, and 5102.1 on ac

12、id and base number byextraction (color-indicator titration) of Federal Test MethodStandard No. 791b. Test results by these methods may or maynot be numerically equivalent to this test method.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included i

13、n thisstandard.1.6 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 and health practices and determine the applica-bility of regulatory limitations prior to use.

14、1.7 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 Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to

15、 Trade (TBT) Committee.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.Current edition approved June 1, 2017. Published July 2017. Or

16、iginally approvedin 1987. Last previous edition approved in 2011 as D4739 11. DOI: 10.1520/D4739-11R17.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recogni

17、zed 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 Trade (TBT) Committee.12. Referenced Documents2.1 ASTM Standards:2D664 Test Method for Ac

18、id Number of Petroleum Productsby Potentiometric TitrationD974 Test Method for Acid and Base Number by Color-Indicator TitrationD1193 Specification for Reagent WaterD2896 Test Method for Base Number of Petroleum Productsby Potentiometric Perchloric Acid TitrationD4057 Practice for Manual Sampling of

19、 Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum Products2.2 IP Standard:3IP 139 Petroleum products and lubricantsDeterminationof acid and base numberColour-indicator titrationmethod2.3 U.S. Federal Test Method:4Federal Test Method Standard No. 791b Lub

20、ricants LiquidFuels and Related Products; Methods of Testing3. Terminology3.1 Definitions:3.1.1 base number, nthe quantity of a specified acid,expressed in terms of the equivalent number of milligrams ofpotassium hydroxide per gram of sample, required to titrate asample in a specified solvent to a s

21、pecified endpoint using aspecified detection system.3.1.1.1 DiscussionIn this test method, the sample istitrated to a meter reading corresponding to aqueous acidicbuffer solution or appropriate inflection point.3.2 Definitions of Terms Specific to This Standard:3.2.1 strong base number, nthe quantit

22、y of acid, expressedin terms of the equivalent number of milligrams of potassiumhydroxide per gram of sample, that is required to titrate asample dissolved in the specified solvent from the initial meterreading to a meter reading corresponding to a basic buffersolution.4. Summary of Test Method4.1 T

23、he sample is dissolved in a mixture of toluene,propan-2-ol (isopropyl alcohol), chloroform, and a smallamount of water and titrated potentiometrically with alcoholichydrochloric acid solution. The test results of this procedureare obtained by titration mode of fixed increment and fixedtime additions

24、 of the titrant. An endpoint is selected from atitration curve according to the criteria given in Section 12 andused to calculate a base number.5. Significance and Use5.1 New and used petroleum products can contain basicconstituents that are present as additives. The relative amountof these material

25、s can be determined by titration with acids.The base number is a measure of the amount of basicsubstances in the oil always under the conditions of the test. Itis sometimes used as a measure of lubricant degradation inservice. However, any condemning limit shall be empiricallyestablished.5.2 As stat

26、ed in 1.2, this test method uses a weaker acid totitrate the base than Test Method D2896, and the titrationsolvents are also different. Test Method D2896 uses a strongeracid and a more polar solvent system than Test Method D4739.As a result, Test Method D2896 will titrate salts of weak acids(soaps),

27、 basic salts of polyacidic bases, and weak alkaline saltsof some metals. They do not protect the oil from acidiccomponents due to the degradation of the oil. This test methodmay produce a falsely exaggerated base number. Test MethodD4739 will probably not titrate these weak bases but, if so, willtit

28、rate them to a lesser degree of completion. It measures onlythe basic components of the additive package that neutralizesacids. On the other hand, if the additive package contains weakbasic components that do not play a role in neutralizing theacidic components of the degrading oil, then the Test Me

29、thodD4739 result may be falsely understated.5.3 Particular care is required in the interpretation of thebase number of new and used lubricants.5.3.1 When the base number of the new oil is required as anexpression of its manufactured quality, Test Method D2896 ispreferred, since it is known to titrat

30、e weak bases that this testmethod may or may not titrate reliably.5.3.2 When the base number of in-service or at-term oil isrequired, this test method is preferred because in many cases,especially for internal combustion engine oils, weakly basicdegradation products are possible. Test Method D2896 w

31、illtitrate these, thus giving a false value of essential basicity. Thistest method may or may not titrate these weak acids.5.3.3 When the loss of base number value, as the oilsproceed in service, is the consideration, this test method is to bepreferred and all values including the unused oil shall b

32、edetermined by this test method. Base numbers obtained by thistest method shall not be related to base numbers obtained byanother test method such as Test Method D2896.5.3.4 In ASTM Interlaboratory Crosscheck Programs forboth new and used lubricants, historically Test Method D2896gives a higher valu

33、e for base number.6. Apparatus6.1 Potentiometric Titration, automatic or manual, withcapability of adding fixed increments of titrant at fixed timeintervals (see Annex A1).6.1.1 The titrimeter must automatically (or manually) con-trol the rate of addition of titrant as follows: Delivery of titrantwi

34、ll be incremental; after delivery of precisely a 0.100 mLincrement (see 6.1.2), the delivery is stopped and a fixed timeperiod of 90 s is allowed to pass before another 0.100 mL2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. F

35、or Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Energy Institute, 61 New Cavendish St., London, W1G 7AR,U.K., http:/www.energyinst.org.4Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,Section D,

36、700 Robbins Ave., Philadelphia, PA 19111-5098.D4739 11 (2017)2increment of titrant is delivered. This procedure is repeateduntil the titration is completed.6.1.2 The precision of addition of the 0.100 mL incrementsof titrant must be 60.001 mL for automatic titrators. Formanual buret, it should be 60

37、.005 mL. A higher incrementalprecision is required for an automatic buret, because the totalvolume to the end point is summed from the individualincrements; it is read from a scale with a manual buret.6.2 Sensing Electrode, standard pH with glass membrane,suitable for non-aqueous titrations.6.3 Refe

38、rence Electrode, Silver/Silver Chloride (Ag/AgCl)reference electrode with sleeve junction, filled with 1 M to 3 MLiCl in ethanol.6.3.1 Combination ElectrodeSensing electrodes may havethe Ag/AgCl reference electrode built into the same electrodebody, which offers the convenience of working with andma

39、intaining only one electrode. The combination electrodeshall have a sleeve junction type of reference and shall use aninert ethanol electrolyte, for example, 1 M to 3 M LiCl inethanol. In the reference compartment, the sensing electrodepart shall use a glass membrane designed for non-aqueoustitratio

40、ns. These combination electrodes shall have the sameresponse or better response than a dual electrode system. Theyshall have removable sleeves for easy rinsing and addition ofelectrolyte. (WarningWhen a movable sleeve is part of theelectrode system, ensure that the sleeve is unimpaired beforeevery t

41、itration.)6.4 Stirrer, Buret, Stand, Titration Vessel, as specified inAnnex A1, are required.7. Reagents7.1 Purity of ReagentsReagent-grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analyt

42、ical Reagents of the American Chemical Society,where such specifications are available.5Other grades may 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 Purity of WaterUnless otherwise in

43、dicated, referencesto water shall be understood to mean reagent water that meetsthe requirement of either Type I, II, or III of SpecificationD1193.7.3 Buffer, Aqueous AcidCommercial pH 3 buffer solutionwith a tolerance of 60.02 pH units at 25 C. This solution shallbe replaced at regular intervals co

44、nsistent with its stability orwhen contamination is suspected. Information related to thestability should be obtained from the manufacturer.7.4 Buffer, Aqueous BasicCommercial pH 10 buffer solu-tion with a tolerance of 60.02 pH units at 25 C. This solutionshall be replaced at regular intervals consi

45、stent with its stabilityor when contamination is suspected. Information related to thestability should be obtained from the manufacturer.7.5 ChloroformReagent grade. (WarningToxic andsuspected carcinogen.)7.6 Hydrochloric Acid Solution, Standard Alcoholic(0.1 M)Mix 9 mL of reagent grade hydrochloric

46、 acid (HCl,sp gr 1.19) (WarningToxic and corrosive), with 1 L ofanhydrous isopropyl alcohol. Standardize frequently enough todetect normality changes of 0.0005 by potentiometric titrationof approximately 8 mL (accurately measured) of the 0.1 Malcoholic KOH solution diluted with 125 mL CO2-free water

47、.7.7 Ethanolreagent grade. (WarningFlammable andtoxic, especially when denatured.)7.8 Lithium Chloride Electrolyte Prepare a solution of1 M to 3 M LiCl in ethanol.7.9 Potassium Hydroxide(WarningCauses severeburns.)7.10 Potassium Hydroxide Solution, Standard Alcoholic(0.1 M)Add 6 g of reagent grade p

48、otassium hydroxide(KOH) (WarningToxic and corrosive), to approximately 1 Lof anhydrous isopropyl alcohol. Boil gently for 10 min to effectsolution. Allow the solution to stand for 2 days, and then filterthe supernatant liquid through a fine sintered-glass funnel.Store the solution in a chemically re

49、sistant bottle. Dispense ina manner such that the solution is protected from atmosphericcarbon dioxide (CO2) by means of a guard tube containingsoda lime or soda non-fibrous silicate absorbent, and such thatit does not come into contact with cork, rubber, or saponifiablestopcock grease. Standardize frequently enough to detectnormality changes of 0.0005 by potentiometric titration ofweighed quantities of potassium acid phthalate dissolved inCO2-free water.7.11 Propan-2-ol (Isopropyl Alcohol)Anhydrous, (lessthan 0.1 % H2O). (WarningFlammable.) If dry reage