1、Designation: D3339 12 (Reapproved 2017)Standard Test Method forAcid Number of Petroleum Products by Semi-Micro ColorIndicator Titration1This standard is issued under the fixed designation D3339; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f 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 covers the determination of acidicconstituents in new or used petroleum produ
3、cts and lubricantssoluble or nearly soluble in mixtures of toluene, and isopropylalcohol. The test method is especially intended for cases inwhich the amount of sample available to be analyzed is toosmall to allow accurate analysis by Test Methods D974 orD664. It is applicable for the determination
4、of acids havingdissociation constants in water larger than 109. Extremelyweak acids having dissociation constants smaller than 109donot interfere. Salts titrate if their hydrolysis constants are largerthan 109.1.2 This test method can be used to indicate relative changesin acid number that occur in
5、an oil during use under oxidizingconditions. Although the titration is made under definiteequilibrium conditions, the method does not measure anabsolute acidic property that can be used to predict perfor-mance of an oil under service conditions. No general relation-ship between bearing corrosion and
6、 acid number is known.1.3 Since this test method requires substantially less samplethan Test Methods D974 or D664, it provides an advantageousmeans of monitoring an oxidation test by changes in acidnumber by (1) minimizing test sample depletion for acidnumber analyses and thus minimizing the disturb
7、ance of thetest or (2) allowing additional acid number analyses to be madewhile maintaining the same test sample depletion and thusproviding additional data.NOTE 1Some oils, such as many cutting oils, rust-proofing oils, andsimilar compounded oils, or excessively dark-colored oils, may be morediffic
8、ult to analyze by this test method due to obscurity of the color-indicator end point. These oils can be analyzed by Test Method D664provided sufficient sample is available. However, this situation is muchless likely using Test Method D3339 than using Test Method D974 due tothe use of a more highly d
9、ilute sample during the titration and due to thegreater stability of the end point color change. The acid numbers obtainedby Test Method D3339 may or may not be numerically the same as thoseobtained by Test Method D664 but they should be of the same order ofmagnitude.NOTE 2The results obtained using
10、 this method have been found to benumerically the same as those obtained using Test Method D974, withinthe precision of the two methods, for new or oxidized lubricants of thetype primarily intended for hydraulic or steam turbine type service. Theoxidized lubricants were obtained using the Test Metho
11、d D943 oxidationtest. This correlation is shown by the correlation coefficient r = 0.989 withslope s = + 1.017 and intercept y = + 0.029, calculated using the acidnumbers obtained using both titration methods for the samples used for theprecision statement (12.2).21.4 The values stated in SI units a
12、re to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 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 practice
13、s and determine the applica-bility of regulatory limitations prior to use. For specificwarning statements, see Sections 7 and 9, A1.1.4, A2.3.1, andA2.10.1.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the D
14、ecision 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:3D664 Test Method for Acid Number of Petroleum Productsby Potentiometric Titrat
15、ionD943 Test Method for Oxidation Characteristics of InhibitedMineral OilsD974 Test Method for Acid and Base Number by Color-Indicator TitrationD1193 Specification for Reagent Water1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants an
16、d 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 1974. Last previous edition approved in 2012 as D3339 12. DOI:10.1520/D3339-12R17.2Use of the correlation coefficient is gi
17、ven in Mack, C., Essentials of Statisticsfor Scientists and Technologists, Plenum Press, New York, NY, 1967, or otherpublications on statistics.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards v
18、olume 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 StatesThis international standard was developed in accordance with internationally recognized principles on st
19、andardization 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.13. Terminology3.1 Definitions:3.1.1 acid number, nthe quantity of a specified base,exp
20、ressed 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, acids or salts withdissociation constants greater than 109, are titrated to a greenend p
21、oint with p-naphtholbenzein indicator.3.1.2 used oil, nany oil that has been in a piece ofequipment (for example, an engine, gearbox, transformer orturbine) whether operated or not.3.1.2.1 DiscussionTypically, in this test method, the acid-ity of oxidized hydraulic or steam turbine oils is measured.
22、4. Summary of Test Method4.1 To determine the acid number a sample of the oil isdissolved in a solvent consisting of toluene, isopropyl alcohol,and a small amount of water. The resulting single-phasesolution is titrated at room temperature under a nitrogenatmosphere with standardized 0.01 M potassiu
23、m hydroxide(KOH) in isopropyl alcohol to the stable green color of theadded p-naphtholbenzein indicator.5. Significance and Use5.1 This test method measures the acid number of oilsobtained from laboratory oxidation tests using smaller amountsof sample than Test Methods D974 or D664. It has specifica
24、pplication in Test Method D943 in which small aliquots of oilare periodically removed for testing by Test Method D3339.This test method, therefore, provides a means of monitoring therelative oxidation of oils, by measuring changes in acidnumber, at different time intervals and under the variousoxidi
25、zing test conditions.6. Apparatus (Refer to Fig. 1)6.1 Titration BuretA micro scale, automatic buret with0.01 mL subdivisions and at least a 2 mL buret capacity.6.2 Titrant ReservoirThe preferred reservoir is one that isintegral with the automatic buret, such as shown in Fig. 1.Atitrant reservoir se
26、parate from the automatic buret may be usedif the line connecting the reservoir with the buret is all glass.Exposure of the titrant to light should be minimized by use ofamber glass for the reservoir, by wrapping the reservoir withfoil such as aluminum foil, or by other suitable means. Also,the tube
27、 in the reservoir for titrant withdrawal is adjusted sothat the end of the tube is about 20 mm from the bottom of thereservoir so that any precipitate that may collect on the bottomof the reservoir will not be disturbed. To further avoiddisturbing any precipitate in the reservoir, movement of theres
28、ervoir must be minimized.6.2.1 With either type of reservoir all entrances and exits tothe buret and reservoir must be connected to absorption tubesto remove atmospheric carbon dioxide and water, for example,tubes containing 10 mesh to 20 mesh anhydrous calcium sul-fate as desiccant and soda-lime as
29、 carbon dioxide absorbent.Precautions must be taken to prevent introduction of anysoda-lime into the titrant reservoir or buret.6.3 Titration Beaker100 mL capacity tall-form Berzeliusbeaker without pouring spout. Approximate dimensions are47 mm in inside diameter and 79 mm in height.6.4 Titration Be
30、aker Purging StopperAstopper to enclosethe titration beaker. The stopper must be composed of anelastomeric material, such as neoprene, that is essentiallyunaffected by the titration solvent. Approximate stopper di-mensions are 53 mm top diameter, 45 mm bottom diameter,and 25 mm height. The stopper i
31、s fitted with a 8 mm outsidediameter glass inlet tube extending 15 mm 6 2 mm beyond thebottom of the stopper and with a 7 mm 6 1 mm insidediameter hole. The inlet tube and hole are placed on oppositesides of the stopper with a center-to-center separation distanceof 30 mm 6 1 mm.6.5 Purge Gas Rotamet
32、er, capable of indicating a flow rateof 10 Lh.6.6 Stirrer Motor, variable speed, magnetically linked.NOTE 3A propeller may also be used instead of a magnetic stirrer tomix the samples.6.7 Stirring Bar, cylindrical, TFE-fluorocarbon encased,25.4 mm long and 7.9 mm in diameter.6.8 Pipet, capable of tr
33、ansferring 0.100 mL 6 0.002 mL oftitration indicator solution.6.9 Titration Solvent BuretA 500 mL or larger capacityburet with 5 mL subdivisions. The top of the buret is stopperedand connected with an absorption tube, as in 6.2, to removeatmospheric carbon dioxide and water.An alternative means ofdi
34、spensing the titration solvent may be used provided adispensing repeatability within 61 mL for 40 mL is obtainableand the solvent in the dispenser is isolated from atmosphericcarbon dioxide and water.NOTE 4An automated photometric device may also be used fordetecting the titration end point. However
35、, the precision estimates given inSection 13 may not apply to this mode of titration.7. Reagents and Materials7.1 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
36、Analytical Reagents of the American Chemical Society,where such specifications are available or to other suchrecognized standards for reagent chemicals.4Other grades maybe used, provided it is first ascertained that the reagent is ofsufficient high purity to permit its use without lessening theaccur
37、acy of the determination.7.2 Purity of WaterAll references to water shall be under-stood to mean freshly distilled (carbon dioxide-free) waterconforming to Specification D1193, Type II or III.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For
38、Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D3339 12 (2017)27.3 Ethyl
39、 Alcohol(WarningFlammable. DenaturedCannot be made nontoxic.) USP 200 proof or denaturedalcohol according to Formula 30 of the U. S. Bureau of InternalRevenue.7.4 Propanol-2-ol, (Isopropyl Alcohol) Anhydrous,(WarningFlammable, see also Note 5.) containing less than0.9 % water.NOTE 5It has been repor
40、ted that, if not inhibited against it, propanol-2-ol can contain peroxides. When this occurs, an explosive mixture ispossible when the storage vessel or other equipment such as a dispensingbottle, are near empty and approaching dryness.7.5 p-Naphtholbenzein Indicator5,6SolutionThep-naphtholbenzein m
41、ust meet the specifications given in AnnexA1. Prepare a solution containing 10 g of p-naphtholbenzeinper litre of titration solvent.5In a 2006 study, only Kodak, Baker (Mallinkrodt), Fluka, and Aldrich werefound to meet the specifications in Annex A1. However, Kodak brand is no longeravailable.6Supp
42、orting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1626. ContactASTM CustomerService at serviceastm.org.FIG. 1 Schematic Drawing of Typical ApparatusD3339 12 (2017)37.6 Nitrogen, dry and carbon dioxide-free.7.6.1 In order to obtain
43、repeatable results and a stable endpoint color change, it is especially important that the nitrogenpurge gas be free of carbon dioxide. Prepurified grade nitrogenhas been found to be satisfactory.7.7 Phenolphthalein Indicator SolutionDissolve 0.10 g ofsolid pure phenolphthalein in 50 mL of water and
44、 50 mL ofethyl alcohol.7.8 Titration SolventConsisting of 5.0 mL 6 0.1 mL ofwater, 495 mL 6 1 mL of anhydrous propanol-2-ol, and500 mL 6 1 mL of toluene.7.9 Potassium Hydroxide Solution, Standard Alcoholic(0.01 M), (WarningCorrosive.)NOTE 6Commercially available reagents may be used in place oflabor
45、atory preparations.7.9.1 Preparation, Add 3 g of solid KOH to approximately1 Lof anhydrous propanol-2-ol (isopropyl alcohol) (containingless than 0.9 % water) in a 2 L Erlenmeyer flask. Boil themixture gently on a steam bath for 10 min to 15 min whilestirring to prevent caking of solids on the botto
46、m of the flask.Add about 1 g of barium hydroxide and again boil gently forabout 10 min. Cool to room temperature, stopper to preventcontact with the room atmosphere and allow to stand overnight(about 16 h). Filter the supernatant liquid through a 10 mTFE-fluorocarbon membrane filter while avoiding u
47、nnecessaryexposure to the atmosphere and then dilute the solution(approximately 0.05 M) with anhydrous isopropyl alcohol to atotal volume of about 5 L (Note 7). Store the titrant in achemically resistant dispensing bottle out of contact with cork,rubber, or saponifiable stopcock lubricant and protec
48、ted by aguard tube containing soda-lime. Minimize exposure of thetitrant to light by storing in the dark or in an amber bottle or bywrapping the bottle with aluminum foil.NOTE 7Care should be taken to ensure a final normality of 0.011 60.002.NOTE 8Because of the relatively large coefficient of cubic
49、 expansionof organic liquids, such as propanol-2-ol, the standard alcoholic solutionsshould be standardized at temperatures close to those employed in thetitrations of samples.7.9.2 StandardizationThe titrant is standardized (Note 8)against dried (at least 1 h at 110 C), pure potassium hydrogenphthalate using the method described in 9.1 for the acidnumber analysis, with the exception that water (40 mL 61 mL) is used as the solvent and 6 drops of phenolphthaleinsolution is used as the indicator. The blank is obtained in thesame manner except that
