ASTM D94-2007 Standard Test Methods for Saponification Number of Petroleum Products《石油产品皂化值标准试验方法》.pdf

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1、Designation: D 94 07Designation: 136S1/98, 136S2/99An American National StandardStandard Test Methods forSaponification Number of Petroleum Products1This standard is issued under the fixed designation D 94; the number immediately following the designation indicates the year of originaladoption or, i

2、n the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 The

3、se test methods cover the determination of theamount of constituents in petroleum products such as lubri-cants, additives, and transmission fluids that will saponifyunder the conditions of the test.NOTE 1Statements defining this test and its significance when appliedto electrical insulating oils of

4、mineral origin will be found in Guide D117.Experience has shown that for transformer oils, Test Method D 94,modified by use of 0.1 M KOH solution and 0.1 M HCl, is more suitable.1.1.1 Two test methods are described: Method AColorIndicator Titration (Sections 6-13), and MethodBPotentiometric Titratio

5、n (Sections 14-23).1.2 Because compounds of sulfur, phosphorus, the halo-gens, and certain other elements that are sometimes added topetroleum products also consume alkali and acids, the resultsobtained indicate the effect of these extraneous materials inaddition to the saponifiable material present

6、. Results on prod-ucts containing such materials, on used internal-combustion-engine crankcase oils, and on used turbine oils must beinterpreted with caution.NOTE 2The materials referred to above, which are not normallyconsidered saponifiable matter, include inorganic or certain organic acids,most n

7、onalkali soaps, and so forth. The presence of such materialsincreases the saponification number above that of fatty saponifiablematerials for which the test method is primarily intended. The odor ofhydrogen sulfide near the end of the back-titration in the saponificationtest is an indication that ce

8、rtain types of reactive sulfur compounds arepresent in the sample. In the case of other reactive sulfur, chlorine, andphosphorus compounds and other interfering materials, no simple indica-tion is given during the test. A gravimetric determination of the actualamount of fatty acids is probably the m

9、ost reliable method for suchcompounds. Test Methods D 128 or IP Method 284/86 can be used todetermine fatty acids gravimetrically.1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its u

10、se. 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. For specific hazardstatements, see Sections 6, 7, 8, 10, 15, 16, 17, and 19.2. Referenced Documents2.1 ASTM Standard

11、s:2D117 Guide for Sampling, Test Methods, and Specifica-tions for Electrical Insulating Oils of Petroleum OriginD 128 Test Methods for Analysis of Lubricating GreaseD 1193 Specification for Reagent WaterD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automat

12、ic Sampling of Petroleum andPetroleum ProductsD 6299 Practice for Applying Statistical Quality AssuranceTechniques to Evaluate Analytical Measurement SystemPerformanceD 6792 Guide for Quality System in Petroleum Productsand Lubricants Testing Laboratories2.2 Energy Institute Standards:3IP 136 Method

13、 of Test for Saponification Number of Petro-leum ProductsIP 284 Method of Test for Fatty Acids3. Terminology3.1 Definitions:1These test methods are under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and are the direct responsibility of Subcommit-tee D02.06 on Analysis o

14、f Lubricants.Current edition approved May 1, 2007. Published May 2007. Originallyapproved in 1921. Last previous edition approved in 2002 as D 9402.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandar

15、ds volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Institute of Petroleum, 61 New Cavendish St., London, W.I.,England.Available from Energy Institute, 61 New Cavendish St., London, WIG7AR, U.K., http:/www.energyinst.org.uk.1*A Summary of Changes se

16、ction appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.1 saponification number, nthe number of milligramsof potassium hydroxide consumed by1gofasample under theconditions of the test.3.1.1.1 Disc

17、ussionThe value of the saponification numberin these test methods can be affected by the presence of otheralkali-reactive species, as described in Note 2.3.1.2 saponify, vto hydrolyze a fat with alkali to form analcohol and the salt of a fatty acid.4. Summary of Test Method4.1 A known mass of the sa

18、mple is dissolved in a suitablesolvent, such as butanone (methylethylketone), xylenes, orStoddard Solvent, or a combination thereof (WarningExtremely flammable. Vapors can cause flash fire), and isheated with a known amount of alcoholic potassium hydroxide(KOH). The excess alkali is titrated with st

19、andard acid, and thesaponification number is calculated.4.2 The titration end point can be detected either colori-metrically (Method A) or potentiometrically (Method B).5. Significance and Use5.1 Petroleum products can contain additives that react withalkali to form metal soaps. Fats are examples of

20、 such additives.Also, certain used engine oils, especially from turbine orinternal combustion engines, can contain chemicals that willsimilarly react with alkali. The saponification number ex-presses the amount of base that will react with1gofsamplewhen heated in a specific manner.This then gives an

21、 estimationof the amount of acid present in the sample, that is, any freeacid originally present plus any combined (for example, inesters) that have been converted to metal soaps during theheating procedure.5.2 Saponification numbers are also used in setting productspecifications for lubricants and

22、additives.METHOD ACOLOR INDICATOR TITRATION6. Apparatus6.1 Erlenmeyer Flask and CondenserAn Erlenmeyerflask, 250 or 300-mL capacity, alkali-resistant (see Note 3) and(WarningCauses severe burns; a recognized carcinogen;strong oxidizercontact with other material can cause fire;hygroscopic), to which

23、is attached a straight or mushroom-typereflux condenser. The straight-type condenser is fitted to theflask with a ground-glass joint; the mushroom-type condensermust fit loosely to permit venting of the flask. Water refluxcondensers can also be used instead of air condensers.NOTE 3Do not use scratch

24、ed or etched Erlenmeyer flasks becauseKOH will react with them. The glassware shall be chemically clean. It isrecommended that flasks be cleaned with chromic acid cleaning solution(Alternatively, Nochromix or similar products can be used.)6.2 Hot PlateA suitable hot plate heated by either elec-trici

25、ty or steam. (WarningThermal hazard; in addition toother precautions, avoid contact with exposed skin.)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

26、 on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other 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.NOTE 4Commercially available

27、 reagents may be used in place oflaboratory preparations, provided they meet the specifications outlined.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type I, II, or III in Specification D 1193.7.3 Alcohol595 % ethanol (Warni

28、ngFlammable.DenaturedCannot be made nontoxic) (see Note 5) and(WarningFlammable) or 95 % ethanol to which has beenadded 10 volume % of methanol (see Note 5 and Note 6)orabsolute alcohol.NOTE 5It has been found that 99 % 2-propanol (isopropyl alcohol)can be substituted for the purified ethanol with e

29、ntirely satisfactory results.This substitution is not permissible, however, in referee tests.NOTE 6This composition is available under the name of “U.S.Department of Treasury Specially Denatured Formula 30 (Regulation No.3-1938).”5Formula 3A plus 5 % methanol is an equivalent.7.4 Aqueous Hydrochlori

30、c Acid Standard Solution (0.5M)Standardize to detect molarity changes of 0.0005 bytitrating with standard alcoholic KOH solution (see 7.8 andNote 7).NOTE 7Where saponification numbers below one are expected, betterprecision can be obtained by substituting 0.1 M KOH solution and HCl forthe 0.5 M reag

31、ents in Sections 7, 8, 10, 17, and 19.7.5 Butanone (Methyl Ethyl Ketone), technical grade. Storein dark or brown bottles. (WarningSee 4.1.)7.6 Naphtha,(WarningExtremely flammable. Harmful ifinhaled. Vapors can cause flash fire.) ASTM PrecipitationGrade (or Petroleum Spirit-60/80 or hexanes) (Warning

32、Combustible. Vapor harmful.) Petroleum spirit shall conformto the current IP 136.7.7 Phenolphthalein Solution, NeutralizedDissolve 1.0 60.1 g of phenolphthalein in 100 mL of alcohol (see 7.3).Neutralize to faint pink color with dilute (0.1 M) alcoholicKOH solution.7.8 Alcoholic Potassium Hydroxide S

33、tandard Solution (0.5M)Prepare approximately 0.5 M solution by dissolving KOHin the alcohol specified in 7.3. Allow the solution to settle in adark place. Filter the solution, and allow to stand for 24 hbefore using.7.8.1 Alternatively prepare 0.5 or 0.1 M alcoholic KOH bymixing a commercially avail

34、able KOH ampule (which is4Reagent 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, BDH Ltd., Poole, Dorset, U.K., and the

35、 United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.5Available from the U.S. Bureau of Alcohol, Tobacco, and Firearms, DistilledSpirits and Tobacco Branch, 1200 Pennsylvania Avenue, NW, Washington, DC20226.D94072carbonate free) with 95 % alcoho

36、l. Using this type solutiongives consistent blanks and does not give multiple breaks (seeNote 8).NOTE 8Because of the relatively large coefficient of cubic expansionof organic liquids such as 2-propanol (isopropyl alcohol), the standardalcoholic solution has to be standardized at temperatures close

37、to thoseemployed in the titrations of samples.7.8.2 The KOH solutions shall be standardized by titratingwith standard potassium hydrogen phthalate solution (see 7.9and Note 8).7.9 Potassium Hydrogen Phthalate(C8H5KO4) 0.1 MStandard SolutionWeigh 2.0422 6 0.0002 g of potassiumhydrogen phthalate that

38、has been dried at 110 6 5C to aconstant weight into a 100-mL volumetric flask. Dissolve inreagent water. Some heating may be necessary to dissolve thesolid. Dilute to 100 mL with distilled or deionized water, afterthe solution has cooled.7.10 Stoddard Solvent, technical grade. (WarningExtremely flam

39、mable. Harmful if inhaled.)7.11 Xylene, reagent grade. (WarningExtremely flam-mable. Harmful if inhaled.)8. Blank Determinations8.1 Perform a blank determination concurrently with eachset (see Note 9) (one or more) of samples as follows: measureaccurately from a buret or volumetric pipet (see Note 1

40、0) intothe Erlenmeyer flask 25 6 0.03 mL of alcoholic KOH solutionand 256 1 mL of butanone (methylethyl-ketone) or one of thealternative solvents. Connect the condenser to the flask, andheat for the same amount of time as that used for the sampleafter refluxing begins. (WarningThe reflux condensersh

41、ould be clamped securely to prevent it from tipping over ontothe hot plate with possible breakage of glassware. See alsoNote 11.) Immediately add 50 mL of ASTM precipitationnaphtha (WarningSee 7.6, also Note 12 and Note 13)bycautiously pouring the naphtha down the condenser (discon-nect condenser if

42、 mushroom-type is used), and titrate the blankwhile hot, without reheating, with 0.5 M hydrochloric acid(HCl) using three drops of neutralized phenolphthalein indica-tor solution.NOTE 9Run blank determinations in duplicate on samples requiringthe highest accuracy. The precision data are based on dup

43、licate blankdeterminations. A single blank is sufficient for routine work.NOTE 10If a volumetric pipet is used to measure the alcoholic KOHsolution, wait 30 s after delivery to allow for complete drainage.NOTE 11Although standard procedure requires 30 min of reflux,some fats are readily saponified a

44、nd complete saponification takes placewithin 10 min. On the other hand, difficult saponifiable materials requiremore than 2 h. Neither the shortened period nor the longer period shouldbe used except by mutual consent of the interested parties.NOTE 12Pouring 50 mL of naphtha down the condenser at the

45、 end ofthe saponification not only rinses the condenser but also cools the reactionmixture.NOTE 13In the case of insulating oils, the addition of ASTMprecipitation naphtha or petroleum spirit is not necessary.8.2 After the indicator color has been discharged, add,dropwise, more indicator solution. I

46、f this addition of indicatorrestores the color, continue the titration, making further drop-wise additions of indicator, if necessary, until the end point isreached (Note 14). The end point is reached when the indicatorcolor is completely discharged and does not immediatelyreappear upon further drop

47、wise addition of the indicatorsolution. Record as V1in 11.1.NOTE 14Avoid emulsification of titration mixture, but ensure phasecontact by swirling the flask vigorously as the end point is approached.9. Sample9.1 Using Practice D 4057 (manual sampling) or PracticeD 4177 (automatic sampling) as a guide

48、line for obtaining arepresentative sample, make sure that the portion of the sampleto be tested appears homogenous. Choose the size of thesample so that the back-titration volume is from 40 to 80 % ofthe blank, but do not exceed a 20-g sample weight (see Note15).NOTE 15The following sample sizes are

49、 suggested:Saponification Number Sample Size, g181 to 400 1111 to 180 271 to 110 331 to 70 516 to 30 100to15 2010. Procedure10.1 Weigh the specimen to the nearest 0.01 g (record as Win 11.1), such as by difference, from a small beaker into theErlenmeyer flask. Add 25 6 1 mL of butanone or one of thealternative solvents (WarningSee 4.1), followed by 25 60.03 mL of alcoholic KOH solution (WarningSee 7.3)measured accurately from a buret or volumetric pipet (see Note7).10.2 Dissolve the difficult to dissolve samples, such aslubricants and ad