1、Designation: D94 07 (Reapproved 2012)Designation: 136S1/98, 136S2/99Standard Test Methods forSaponification Number of Petroleum Products1This standard is issued under the fixed designation D94; the number immediately following the designation indicates the year of originaladoption or, in the case of
2、 revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () 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. Scope1.1 These test methods
3、 cover the determination of theamount of constituents in petroleum products such aslubricants, 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 mineral origin wi
4、ll be found in Guide D117.Experience has shown that for transformer oils, Test Method D94,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 Titration (Sections 14-23)
5、.1.2 Because compounds of sulfur, phosphorus, thehalogens, and certain other elements that are sometimes addedto petroleum products also consume alkali and acids, theresults obtained indicate the effect of these extraneous materi-als in addition to the saponifiable material present. Results onproduc
6、ts containing such materials, on used internal-combustion-engine crankcase oils, and on used turbine oilsmust be interpreted with caution.NOTE 2The materials referred to above, which are not normallyconsidered saponifiable matter, include inorganic or certain organic acids,most nonalkali soaps, and
7、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 certain types of react
8、ive 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 most reliable method
9、for suchcompounds. Test Methods D128 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 use. It is theresponsi
10、bility 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 Standards:2D117 Guide for Sam
11、pling, Test Methods, and Specificationsfor Electrical Insulating Oils of Petroleum OriginD128 Test Methods for Analysis of Lubricating GreaseD1193 Specification for Reagent WaterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum an
12、dPetroleum ProductsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6792 Practice for Quality System in Petroleum Productsand Lubricants Testing Laboratories2.2 Energy Institute Standards:3IP 136 Method of T
13、est for Saponification Number of Petro-leum ProductsIP 284 Method of Test for Fatty Acids3. Terminology3.1 Definitions:3.1.1 saponification number, nthe number of milligramsof potassium hydroxide consumed by1gofasample under theconditions of the test.3.1.1.1 DiscussionThe value of the saponification
14、 number1These 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 of Lubricants.Current edition approved Nov. 1, 2012. Published November 2012. Originallyapproved in 1921. Last previou
15、s edition approved in 2007 as D9407. DOI:10.1520/D0094-07R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.
16、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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United State
17、s1in 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 sample is dissolved in a suitablesolvent, su
18、ch 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 standard acid, and thesaponification number
19、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 such additives.Also, certain used engine
20、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 estimationof the amount of acid present i
21、n 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 additives.METHOD ACOLOR INDICATOR TITRATIO
22、N6. Apparatus6.1 Erlenmeyer Flask and Condenser An 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 is attached a straight or mushroom-type
23、reflux condenser. The straight-type condenser is fitted tothe flask with a ground-glass joint; the mushroom-type con-denser must fit loosely to permit venting of the flask. Waterreflux condensers can also be used instead of air condensers.NOTE 3Do not use scratched or etched Erlenmeyer flasks becaus
24、eKOH 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-tricity or steam. (WarningThermal hazard;
25、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 on Analytical Reagents of the Americ
26、an 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 reagents may be used in place oflabo
27、ratory 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 D1193.7.3 Alcohol595 % ethanol (WarningFlammable.DenaturedCannot be made no
28、ntoxic) (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 entirely satisfactory results.This subs
29、titution 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 Hydrochloric Acid Standard Solution (0.5M)Standar
30、dize 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 reagents in Sections 7, 8, 10, 17, and 19.
31、7.5 Butanone (Methyl Ethyl Ketone) , technical grade. Storein dark or brown bottles. (Warning See 4.1.)7.6 Naphtha, (Warning Extremely flammable. Harmfulif inhaled. Vapors can cause flash fire.) ASTM PrecipitationGrade (or Petroleum Spirit-60/80 or hexanes) (WarningCombustible. Vapor harmful.) Petro
32、leum 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 Standard Solution (0.5M)Prepare app
33、roximately 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 available KOH ampule (which iscarbonate
34、 free) with 95 % alcohol. Using this type solutiongives consistent blanks and does not give multiple breaks (seeNote 8).4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemica
35、l 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.5Available from the U.S. Bureau of Alcohol, Tobacco, and Firearms, DistilledSpirits and Tobacco B
36、ranch, 1200 Pennsylvania Avenue, NW, Washington, DC20226.D94 07 (2012)2NOTE 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 to thoseemployed in the ti
37、trations 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 Solution Weigh 2.0422 6 0.0002 g of potassiumhydrogen phthalate that has been dried at 110 6 5
38、C 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 flammable. Harmful if inhaled
39、.)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 10) intothe Erlenmeyer fla
40、sk 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 condensershould be clamped securely
41、to prevent it from tipping over ontothe hot plate with possible breakage of glassware. See alsoNote 11. ) Immediately add 50 mL of ASTM precipitationnaphtha (Warning See 7.6, also Note 12 and Note 13)bycautiously pouring the naphtha down the condenser (discon-nect condenser if mushroom-type is used)
42、, 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 duplicate blankdeterminati
43、ons. 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, somefats are readily saponified and complete saponificat
44、ion takes place within10 min. On the other hand, difficult saponifiable materials require morethan 2 h. Neither the shortened period nor the longer period should be usedexcept by mutual consent of the interested parties.NOTE 12Pouring 50 mL of naphtha down the condenser at the end ofthe saponificati
45、on 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. If this addition of indi
46、catorrestores 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 dropwise addition of the in
47、dicatorsolution. 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 D4057 (manual sampling) or PracticeD4177 (automatic sampling) as a guideline for obtaining arepre
48、sentative 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 suggested:Saponification
49、 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 additives, first in 15 to
