1、Designation: D7593 13D7593 14Standard 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 re
2、vision, 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. Scope Scope*1.1 This test method covers the determination of fuel dilution for in-service engine oil by gas
3、 chromatography.1.2 Analysis can be performed directly by this test method without pretreatment or dilution of the sample.1.3 There is no limitation for the determination of the dilution range, provided the amount of sample is within the linear rangeof the gas chromatograph detector. However, sample
4、 dilution can add potential error to the result and may affect the precisionobtained as compared to the values presented 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) for gasoline.1.
5、5 The values stated in SI units are to be regarded as standard. Where non-SI units are provided, they are shown in parentheses.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish
6、appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D86 Test Method for Distillation of Petroleum Products at Atmospheric PressureD3524 Test Method for Diesel Fuel Diluent in Used Diesel Engine Oils
7、by Gas ChromatographyD3525 Test Method for Gasoline Diluent in Used Gasoline Engine Oils by Gas ChromatographyE355 Practice for Gas Chromatography Terms and RelationshipsE594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid ChromatographyE1510 Practice for Installin
8、g Fused Silica Open Tubular Capillary Columns in Gas Chromatographs3. Terminology3.1 Definitions:3.1.1 This test method makes reference to common gas chromatographic procedures, terms, and relationships. Detaileddefinitions of these can be found in Practices E355 and E594.3.1.2 fuel dilution, nthe a
9、mount, expressed as a percentage, of engine fuel found in the in-service lubricating oil.3.1.3 fuel diluent, nin service oil analysis, is the unburned fuel components that enter the engine crankcase causing dilutionof the oil.3.1.4 in-service oil, nlubricating oil that is present in a machine that h
10、as been at operating temperature for at least one hour.3.1.5 Marker Peak (MP), na marker peak is a chromatographic peak used to differentiate sections of a chromatogram byretention time.3.1.5.1 Discussion1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid
11、Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.96.02 on Chemistry for the Evaluation of In-Service Lubricants.Current edition approved Dec. 1, 2013Oct. 1, 2014. Published January 2014October 2014. Originally approved in 2013. Last previous edition approved in 2013 asD7593
12、13. DOI: 10.1520/D7593-13.10.1520/D7593-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is n
13、ot an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropria
14、te. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1F
15、or example, components that elute before this marker peak may be considered “fuel,” while components that elute after thismarker peak would be considered “oil.” This marker peak retention time could also serve as the timing for physical changes inthe chromatographic system, such as the time to initi
16、ate a valve change or a back-flush.3.2 Abbreviations:3.2.1 A common abbreviation of carbon compounds is to designate the number of carbon atoms in the compound. A prefix isused to designate the carbon chain form, while a subscripted suffix denotes the number of carbon atoms. For example, normaleicos
17、ane = n-C20.4. Summary of Test Method4.1 A representative aliquot of in-service engine oil is introduced into a gas chromatograph through a programmable splitinjector. Carrier gas transports the vaporized aliquot through the dimethyl polysiloxane bonded phase capillary column where thehydrocarbons a
18、re separated by the chromatographic process. Once the hydrocarbons of interest are sensed by the flame ionizationdetector, the carrier gas pressure/flow at the head of the column is lowered and an auxiliary gas supply located at the end of thecolumn is increased. The change in pressure forces the di
19、rection of the carrier gas to reverse direction and flow back through theinjector.The residual hydrocarbons on the column are back-flushed out of the injector through a charcoal trap and out the split vent.The detector signal is processed by an electronic data acquisition system and the fuel profile
20、 is grouped into gasoline, diesel, andbiodiesel. The components are identified by comparing their retention times to ones identified by analyzing standards underidentical conditions. The concentrations of all components are determined by percent area by normalization of the peak areas.5. Significanc
21、e and Use5.1 Some fuel dilution of in-service engine oil is normal under typical operating conditions. However, excessive fuel dilutioncan lead to decreased performance, premature wear, or sudden engine failure. This test method provides a means of quantifyingthe level of fuel dilution, allowing the
22、 user to take necessary action. This test method does not purport to accurately quantify thespecific fuel present in the in-service lubricant samples due to limitations associated with the aging and degradation of the fuel inthe crankcase. Rather, quantification of diesel fuel is normalized using a
23、simulated aged fuel.6. Interferences6.1 There may be some overlap of the boiling ranges of gasoline, diesel, and biodiesel fuels and some new oils could have lighthydrocarbons or formulated additives present from manufacturing. As a result, small deviations in quantitative analysis couldaccrue when
24、testing unknown or mixed brands of in-service engine oil.7. Apparatus7.1 Gas ChromatographThe following gas chromatographic system performance characteristics are required:7.2 DetectorThis test method requires a flame ionization detector (FID). The detector shall have sufficient sensitivity to detec
25、t0.5 mass % fuel dilution by area on the data acquisition device under the conditions recommended in this test method. The detectorshall meet or exceed the specifications as detailed in Practice E594. The detector shall be capable of operating continuously at400C350 C and connected to the column suc
26、h that no temperature zones below the column temperature (cold spots) exist.7.3 InjectorThe preferred injector is a programmable pneumatically controlled split capillary injector capable of operatingcontinuously at 350C350 C and maintaining a split ratio of 100/1. Connection of the column to the inj
27、ector shall be such thatno temperature zones below the column temperature (cold spots) exist. It is recommended the injector contain an injector linerpacked with silanized glass wool or equivalent liner and that the split vent flows through a trap packed with activated charcoalbefore releasing the c
28、arrier gas to the atmosphere. The programmable injector is preferred for its rapid cooling during injectormaintenance but an isothermal split injector can be used with slower cooling.7.4 Back-Flush DeviceSufficient injector carrier gas pressure/flow should be maintained until the marker peak elutes,
29、 markingthe point of back-flush. Under the recommended conditions within this test method the dodecane marker peak (for gasoline fueldilution) should elute within 0.60.6 min and 0.9 min. The eicosane marker peak (for diesel fuel dilution) should elute within1.51.5 min and 2.1 min. The heneicosane ma
30、rker peak (for biodiesel fuel dilution) should elute within 1.81.8 min and 2.4 min.Once the marker peaks elute, reduce injector carrier gas pressure/flow and increase the back-flush carrier gas pressure/flow to allowback-flush of oil matrix off the column. Consult instrument vendor for specific hard
31、ware and operational conditions.7.5 Pneumatic ControllersThe gas chromatograph shall be capable of maintaining carrier gas pressure constant to 61 % forboth the injector and the detector. Most modern gas chromatographs can control carrier gas in either pressure control mode or flowcontrol mode. The
32、back-flush procedure can be accomplished with either differential pressure or differential flow. The basicfunction is to inject with a high injector carrier and a low auxiliary carrier at the back-flush device so that a forward flow of carrieris established for chromatography.At the desired time, de
33、crease the injector carrier and increase the auxiliary carrier to cause theback-flush. The difference in carrier between the injector and the back-flush device will determine the direction of carrier flow. Thereverse flow shall be higher than the forward flow to cause the back-flush. Nominal dimensi
34、ons of all tubing and restrictors willD7593 142affect pressures and flows as well as temperatures in multiple heated zones such as injector, oven and detector.This analysis utilizesan isothermal oven temperature therefore constant flow control will not improve chromatographic throughput or efficienc
35、y. Atisothermal oven temperatures, both pressure and flow will remain constant.7.6 Column ConditionsThis test method utilizes a fused silica open tubular column with dimethyl polysiloxane cross bondphase internal coating operating isothermally at 225C.225 C.7.6.1 Open tubular column with a cross bon
36、d 100 % dimethyl polysiloxane phase internal coating, 15 m by 0.25 mm ID witha 0.25 m film thickness.7.7 Sample Introduction Devices:7.7.1 MicrosyringeA microsyringe is used for sample introduction capable of precise 0.1 L injections.7.7.2 AutosamplerAutomatic sampling device that reproducibly injec
37、ts 0.1 lL volume is required. The sample introductiondevice should operate in a synchronous manner with the gas chromatograph.7.8 Electronic Data Acquisition SystemAny data acquisition and integration device used for quantification of these analysesshall meet or exceed these minimum requirements:7.8
38、.1 Normalized percent calculations based on peak area or peak height.7.8.2 Ability to construct a first order linear regression calibration curve for up to as many as 10 levels of calibration.7.8.3 Identification of individual components based on retention time, named groups, or timed groups.7.8.4 B
39、aseline corrections for positive or negative sloping baseline.7.8.5 Non-resolved peaks separated by perpendicular drop line.7.8.6 Ability to turn on and off integration.7.8.7 Ability to adjust integration stop and start of each component.8. Reagents and Materials8.1 Purity of ReagentsReagent grade c
40、hemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the committee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available.3 Other grades may be used, provided it is pure enough
41、 to be used without lessening the accuracyof the determination.8.1.1 Base Oil75 mm2/s (cSt) 40C40 C mineral oil. Used as a base oil to make the calibration standards and can be usedas the preferred solvent to rinse the syringe. Other base stocks may be used, however alternate materials such as new a
42、dditizedengine oils may yield a bias in the results.8.1.2 Carbon Disulfide (CS2), 99+ % pure. (WarningExtremely flammable and toxic liquid.) One of the solvents that can beused as a solvent to rinse the syringe.8.2 GasThe following compressed gases are utilized for the operation of the gas chromatog
43、raph.8.2.1 Helium, 99.999 %. (WarningCompressed gas under high pressure.) This gas can be used as carrier gas. Ensuresufficient pressure for a constant carrier gas flow rate. It is not to contain more than 5 mL/m3 of oxygen and the total amount ofimpurities are not to exceed 10 mL/m3. Precision in t
44、his method is based on helium as the carrier gas; however, nitrogen,hydrogen and argon have been successfully used as the carrier gas.8.2.2 Nitrogen, 99.999 %. (WarningCompressed gas under high pressure.) If May be used as a carrier gas, it is not to containmore than 5 mL/man alternative carrier gas
45、.3 of oxygen and the total amount of impurities is not to exceed 10 mL/m3.8.2.3 Argon, 99.999 %. (WarningCompressed gas under high pressure.) If May be used as a carrier gas, it is not to containmore than 5 mL/man alternative carrier gas.3 of oxygen and the total amount of impurities is not to excee
46、d 10 mL/m3.8.2.4 Hydrogen, 99.999 %. (WarningExtremely flammable compressed gas under high pressure.) The total amount ofimpurities is not to exceed 10 mL/m3. This gas is used to supply fuel to the flame ionization detector (FID).8.2.5 Air, (WarningCompressed gas under high pressure.) The total amou
47、nt of impurities is not to exceed 10 mLm3. Thisgas is used to supply oxidant to the flame ionization detector (FID).8.3 Aged FuelAged diesel fuel is prepared by distilling the fuel in accordance with Test Method D86 and stopping thedistillation process after 10 % of the fuel has been distilled over.
48、 The 90 % fuel remaining in the distillation flask is the aged dieselfuel.8.4 Quantification of unknown samples may be affected by the specific sources of fuel used in the calibration. In addition, fuelmay age and degrade at different rates and by varying mechanisms once present in the engines lubri
49、cant. Biodiesel blends andmany ultra-low sulfur diesel fuels contain varying concentrations of fatty acid methyl esters and the specific concentration ofbiodiesel in any given vehicles fuel tank may not be known with certainty. It is beyond the scope of this test method to requirethat calibration standards closely match the fuel found in the samples. The aging of the fuel standards provides an approximation3 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing
