1、Designation: D7593 13Standard Test Method forDetermination of Fuel Dilution for In-Service Engine Oils byGas Chromatography1This standard is issued under the fixed designation D7593; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、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 fueldilution for in-service engine oil by gas chromatography.
3、1.2 Analysis can be performed directly by this test methodwithout pretreatment or dilution of the sample.1.3 There is no limitation for the determination of thedilution range, provided the amount of sample is within thelinear range of the gas chromatograph detector. However,sample dilution can add p
4、otential error to the result and mayaffect the precision obtained as compared to the values pre-sented in Section 14, which were obtained with no dilution.1.4 This test method covers a quantitation range up to 10 %(m/m) for diesel and biodiesel, and up to 5 % (m/m) forgasoline.1.5 The values stated
5、in SI units are to be regarded asstandard. Where non-SI units are provided, they are shown inparentheses.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
6、 health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D86 Test Method for Distillation of Petroleum Products atAtmospheric PressureD3524 Test Method for Diesel Fuel Diluent in Used DieselEngine Oils by Gas Chromatography
7、(Withdrawn 2013)3D3525 Test Method for Gasoline Diluent in Used GasolineEngine Oils by Gas ChromatographyE355 Practice for Gas Chromatography Terms and Relation-shipsE594 Practice for Testing Flame Ionization Detectors Usedin Gas or Supercritical Fluid ChromatographyE1510 Practice for Installing Fus
8、ed Silica Open TubularCapillary Columns in Gas Chromatographs3. Terminology3.1 Definitions:3.1.1 This test method makes reference to common gaschromatographic procedures, terms, and relationships. Detaileddefinitions of these can be found in Practices E355 and E594.3.1.2 fuel dilution, nthe amount,
9、expressed as apercentage, of engine fuel found in the in-service lubricatingoil.3.1.3 fuel diluent, nin service oil analysis, is the unburnedfuel components that enter the engine crankcase causingdilution of the oil.3.1.4 in-service oil, nlubricating oil that is present in amachine that has been at
10、operating temperature for at least onehour.3.1.5 Marker Peak (MP), na marker peak is a chromato-graphic peak used to differentiate sections of a chromatogramby retention time.3.1.5.1 DiscussionFor example, components that elutebefore this marker peak may be considered “fuel,” whilecomponents that el
11、ute after this marker peak would be consid-ered “oil.” This marker peak retention time could also serve asthe timing for physical changes in the chromatographic system,such as the time to initiate a valve change or a back-flush.3.2 Abbreviations:3.2.1 A common abbreviation of carbon compounds is tod
12、esignate the number of carbon atoms in the compound. Aprefix is used to designate the carbon chain form, while asubscripted suffix denotes the number of carbon atoms. Forexample, normal eicosane = n-C20.4. Summary of Test Method4.1 A representative aliquot of in-service engine oil isintroduced into
13、a gas chromatograph through a programmablesplit injector. Carrier gas transports the vaporized aliquot1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.96.02 on Chemistry for the Ev
14、aluation of In-Service Lubricants.Current edition approved Dec. 1, 2013. Published January 2014. DOI: 10.1520/D7593-13.2For 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
15、to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1through the dimethyl polysiloxane bonded pha
16、se capillarycolumn where the hydrocarbons are separated by the chromato-graphic process. Once the hydrocarbons of interest are sensedby the flame ionization detector, the carrier gas pressure/flow atthe head of the column is lowered and an auxiliary gas supplylocated at the end of the column is incr
17、eased. The change inpressure forces the direction of the carrier gas to reversedirection and flow back through the injector. The residualhydrocarbons on the column are back-flushed out of theinjector through a charcoal trap and out the split vent. Thedetector signal is processed by an electronic dat
18、a acquisitionsystem and the fuel profile is grouped into gasoline, diesel, andbiodiesel. The components are identified by comparing theirretention times to ones identified by analyzing standards underidentical conditions. The concentrations of all components aredetermined by percent area by normaliz
19、ation of the peak areas.5. Significance and Use5.1 Some fuel dilution of in-service engine oil is normalunder typical operating conditions. However, excessive fueldilution can lead to decreased performance, premature wear, orsudden engine failure. This test method provides a means ofquantifying the
20、level of fuel dilution, allowing the user to takenecessary action. This test method does not purport to accu-rately quantify the specific fuel present in the in-servicelubricant samples due to limitations associated with the agingand degradation of the fuel in the crankcase. Rather, quantifi-cation
21、of diesel fuel is normalized using a simulated aged fuel.6. Interferences6.1 There may be some overlap of the boiling ranges ofgasoline, diesel, and biodiesel fuels and some new oils couldhave light hydrocarbons or formulated additives present frommanufacturing. As a result, small deviations in quan
22、titativeanalysis could accrue when testing unknown or mixed brandsof in-service engine oil.7. Apparatus7.1 Gas ChromatographThe following gas chromato-graphic system performance characteristics are required:7.2 DetectorThis test method requires a flame ionizationdetector (FID). The detector shall ha
23、ve sufficient sensitivity todetect 0.5 mass % fuel dilution by area on the data acquisitiondevice under the conditions recommended in this test method.The detector shall meet or exceed the specifications as detailedin Practice E594. The detector shall be capable of operatingcontinuously at 400C and
24、connected to the column such thatno temperature zones below the column temperature (coldspots) exist.7.3 InjectorThe preferred injector is a programmablepneumatically controlled split capillary injector capable ofoperating continuously at 350C and maintaining a split ratioof 100/1. Connection of the
25、 column to the injector shall be suchthat no temperature zones below the column temperature (coldspots) exist. It is recommended the injector contain an injectorliner packed with silanized glass wool or equivalent liner andthat the split vent flows through a trap packed with activatedcharcoal before
26、 releasing the carrier gas to the atmosphere. Theprogrammable injector is preferred for its rapid cooling duringinjector maintenance but an isothermal split injector can beused with slower cooling.7.4 Back-Flush DeviceSufficient injector carrier gaspressure/flow should be maintained until the marker
27、 peakelutes, marking the point of back-flush. Under the recom-mended conditions within this test method the dodecanemarker peak (for gasoline fuel dilution) should elute within 0.6and 0.9 min. The eicosane marker peak (for diesel fueldilution) should elute within 1.5 and 2.1 min. The heneicosanemark
28、er peak (for biodiesel fuel dilution) should elute within1.8 and 2.4 min. Once the marker peaks elute, reduce injectorcarrier gas pressure/flow and increase the back-flush carrier gaspressure/flow to allow back-flush of oil matrix off the column.Consult instrument vendor for specific hardware and op
29、era-tional conditions.7.5 Pneumatic ControllersThe gas chromatograph shallbe capable of maintaining carrier gas pressure constant to61 % for both the injector and the detector. Most modern gaschromatographs can control carrier gas in either pressurecontrol mode or flow control mode. The back-flush p
30、rocedurecan be accomplished with either differential pressure or differ-ential flow. The basic function is to inject with a high injectorcarrier and a low auxiliary carrier at the back-flush device sothat a forward flow of carrier is established for chromatogra-phy. At the desired time, decrease the
31、 injector carrier andincrease the auxiliary carrier to cause the back-flush. Thedifference in carrier between the injector and the back-flushdevice will determine the direction of carrier flow. The reverseflow shall be higher than the forward flow to cause theback-flush. Nominal dimensions of all tu
32、bing and restrictorswill affect pressures and flows as well as temperatures inmultiple heated zones such as injector, oven and detector. Thisanalysis utilizes an isothermal oven temperature thereforeconstant flow control will not improve chromatographicthroughput or efficiency.At isothermal oven tem
33、peratures, bothpressure and flow will remain constant.7.6 Column ConditionsThis test method utilizes a fusedsilica open tubular column with dimethyl polysiloxane crossbond phase internal coating operating isothermally at 225C.7.6.1 Open tubular column with a cross bond 100 % dim-ethyl polysiloxane p
34、hase internal coating, 15 m by 0.25 mm IDwith a 0.25 m film thickness.7.7 Sample Introduction Devices:7.7.1 MicrosyringeA microsyringe is used for sampleintroduction capable of precise 0.1 L injections.7.7.2 AutosamplerAutomatic sampling device that repro-ducibly injects 0.1 l volume is required. Th
35、e sample intro-duction device should operate in a synchronous manner withthe gas chromatograph.7.8 Electronic Data Acquisition SystemAny data acquisi-tion and integration device used for quantification of theseanalyses shall meet or exceed these minimum requirements:7.8.1 Normalized percent calculat
36、ions based on peak area orpeak height.7.8.2 Ability to construct a first order linear regressioncalibration curve for up to as many as 10 levels of calibration.D7593 1327.8.3 Identification of individual components based on re-tention time, named groups, or timed groups.7.8.4 Baseline corrections fo
37、r positive or negative slopingbaseline.7.8.5 Non-resolved peaks separated by perpendicular dropline.7.8.6 Ability to turn on and off integration.7.8.7 Ability to adjust integration stop and start of eachcomponent.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in
38、all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused, provided it is pure enough to be used without lesseni
39、ngthe accuracy of the determination.8.1.1 Base Oil75 mm2/s (cSt) 40C mineral oil. Usedas a base oil to make the calibration standards and can be usedas the preferred solvent to rinse the syringe. Other base stocksmay be used, however alternate materials such as new ad-ditized engine oils may yield a
40、 bias in the results.8.1.2 Carbon Disulfide (CS2), 99+ % pure. (WarningExtremely flammable and toxic liquid.) One of the solventsthat can be used as a solvent to rinse the syringe.8.2 GasThe following compressed gases are utilized forthe operation of the gas chromatograph.8.2.1 Helium, 99.999 %. (Wa
41、rningCompressed gas un-der high pressure.) This gas can be used as carrier gas. Ensuresufficient pressure for a constant carrier gas flow rate. It is notto contain more than 5 mL/m3of oxygen and the total amountof impurities are not to exceed 10 mL/m3. Precision in thismethod is based on helium as t
42、he carrier gas; however,nitrogen, hydrogen and argon have been successfully used asthe carrier gas.8.2.2 Nitrogen, 99.999 %. (WarningCompressed gas un-der high pressure.) If used as a carrier gas, it is not to containmore than 5 mL/m3of oxygen and the total amount ofimpurities is not to exceed 10 mL
43、/m3.8.2.3 Argon, 99.999 %. (WarningCompressed gas underhigh pressure.) If used as a carrier gas, it is not to contain morethan 5 mL/m3of oxygen and the total amount of impurities isnot to exceed 10 mL/m3.8.2.4 Hydrogen, 99.999 %. (WarningExtremely flam-mable compressed gas under high pressure.) The
44、total amountof impurities is not to exceed 10 mL/m3. This gas is used tosupply fuel to the flame ionization detector (FID).8.2.5 Air, (WarningCompressed gas under high pres-sure.) The total amount of impurities is not to exceed 10 mL/m3. This gas is used to supply oxidant to the flame ionizationdete
45、ctor (FID).8.3 Aged FuelAged diesel fuel is prepared by distillingthe fuel in accordance with Test Method D86 and stopping thedistillation process after 10 % of the fuel has been distilledover. The 90 % fuel remaining in the distillation flask is theaged diesel fuel.8.4 Quantification of unknown sam
46、ples may be affected bythe specific sources of fuel used in the calibration. In addition,fuel may age and degrade at different rates and by varyingmechanisms once present in the engines lubricant. Biodieselblends and many ultra-low sulfur diesel fuels contain varyingconcentrations of fatty acid meth
47、yl esters and the specificconcentration of biodiesel in any given vehicles fuel tank maynot be known with certainty. It is beyond the scope of this testmethod to require that calibration standards closely match thefuel found in the samples. The aging of the fuel standardsprovides an approximation of
48、 the actual fuel degradation inthe engine oil and it should be noted that this test method is forthe determination of fuel dilution and not for specific quanti-fication of fuel blends or types.8.5 Marker Peak Definitions:8.5.1 n-Dodecane 99 % minimum purity (n-C12) Used tosignify the end boiling ran
49、ge of gasoline.8.5.2 n-Eicosane 99 % minimum purity (n-C20). Used tosignify the end boiling range of diesel.8.5.3 n-Heneicosane 99 % minimum purity (n-C21). Used tosignify the end boiling range of biodiesel.9. Preparation of Apparatus9.1 Gas Chromatograph Setup:9.1.1 Install the gas chromatograph and place into operationin accordance with the manufacturers instructions. Exampleconditions are listed in Appendix X1.9.1.2 The injector liner and septum should be periodicallyinspected and replaced if necessary to remove extraneousdeposits and improve inj
