1、Designation: D7624 10Standard Test Method forCondition Monitoring of Nitration in In-Service Petroleumand Hydrocarbon-Based Lubricants by Trend AnalysisUsing Fourier Transform Infrared (FT-IR) Spectrometry1This standard is issued under the fixed designation D7624; the number immediately following th
2、e designation indicates the year oforiginal adoption or, in the case of 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
3、monitoring nitration in gasolineand natural gas engine oils as well as in other types oflubricants where nitration by-products may form due to thecombustion process or other routes of formation of nitrationcompounds.1.2 This test method uses FT-IR spectroscopy for monitor-ing build-up of nitration b
4、y-products in in-service petroleumand hydrocarbon-based lubricants as a result of normal ma-chinery operation. Nitration levels in gasoline and natural gasengine oils rise as combustion by-products react with the oil asa result of exhaust gas recirculation or a blow-by. This testmethod is designed a
5、s a fast, simple spectroscopic check formonitoring of nitration in in-service petroleum andhydrocarbon-based lubricants with the objective of helpingdiagnose the operational condition of the machine based onmeasuring the level of nitration in the oil.1.3 Acquisition of FT-IR spectral data for measur
6、ing nitra-tion in in-service oil and lubricant samples is described inPractice D7418. In this test method, measurement and datainterpretation parameters for nitration using both direct trendanalysis and differential (spectral subtraction) trend analysisare presented.1.4 This test method is based on
7、trending of spectralchanges associated with nitration in in-service petroleum andhydrocarbon-based lubricants. For direct trend analysis, valuesare recorded directly from absorption spectra and reported inunits of 100*absorbance per 0.1 mm pathlength (or equiva-lently absorbance units per centimetre
8、). For differential trendanalysis, values are recorded from the differential spectra(spectrum obtained by subtraction of the spectrum of thereference oil from that of the in-service oil) and reported inunits of 100*absorbance per 0.1 mm pathlength (or equiva-lently absorbance units per centimetre).
9、Warnings or alarmlimits can be set on the basis of a fixed maximum value for asingle measurement or, alternatively, can be based on a rate ofchange of the response measured. (1)2In either case, suchmaintenance action limits should be determined through sta-tistical analysis, history of the same or s
10、imilar equipment,round robin tests or other methods in conjunction with thecorrelation of nitration changes to equipment performance.NOTE 1It is not the intent of this test method to establish orrecommend normal, cautionary, warning or alert limits for any machinery.Such limits should be established
11、 in conjunction with advice and guidancefrom the machinery manufacturer and maintenance group.1.5 This test method is for petroleum and hydrocarbon-based lubricants and is not applicable for ester-based oils,including polyol esters or phosphate esters.1.6 The values stated in SI units are to be rega
12、rded asstandard. No other units of measurement are included in thisstandard.1.6.1 ExceptionThe unit for wave numbers is cm-1.1.7 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 app
13、ro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D445 Test Method for Kinematic Viscosity of Transparentand Opaque Liquids (and Calculation of Dynamic Viscos-ity)D2896 Test Method for Base Number
14、of Petroleum Prod-ucts by Potentiometric Perchloric Acid TitrationD5185 Test Method for Determination of Additive Ele-ments, Wear Metals, and Contaminants in Used Lubricat-ing Oils and Determination of Selected Elements in BaseOils by Inductively Coupled Plasma Atomic EmissionSpectrometry (ICP-AES)1
15、This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.96.03 on FTIR Testing Practices and Techniques Related to In-ServiceLubricants.Current edition approved Aug. 1, 2010. Published September 2010. DOI
16、:10.1520/D762410.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For 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 s
17、tandards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D6304 Test Method for Determination of Water in Petro-leum Products, Lubricating Oils, and Additives by Coulo-metric Karl Fischer Titra
18、tionD7412 Test Method for Condition Monitoring of PhosphateAntiwear Additives in In-Service Petroleum and Hydro-carbon Based Lubricants by Trend Analysis Using FourierTransform Infrared (FT-IR) SpectrometryD7414 Test Method for Condition Monitoring of Oxidationin In-Service Petroleum and Hydrocarbon
19、 Based Lubri-cants by Trend Analysis Using Fourier Transform Infrared(FT-IR) SpectrometryD7415 Test Method for Condition Monitoring of SulfateBy-Products in In-Service Petroleum and HydrocarbonBased Lubricants by Trend Analysis Using Fourier Trans-form Infrared (FT-IR) SpectrometryD7418 Practice for
20、 Set-Up and Operation of Fourier Trans-form Infrared (FT-IR) Spectrometers for In-Service OilCondition MonitoringE131 Terminology Relating to Molecular SpectroscopyE2412 Practice for Condition Monitoring of In-ServiceLubricants by Trend Analysis Using Fourier TransformInfrared (FT-IR) Spectrometry3.
21、 Terminology3.1 Definitions:3.1.1 For definitions of terms relating to infrared spectros-copy used in this test method, refer to Terminology E131. Fordefinition of terms related to in-service oil condition monitor-ing, refer to Practice D7418.3.1.2 machinery health, na qualitative expression of theo
22、perational status of a machine sub-component, component orentire machine, used to communicate maintenance and opera-tional recommendations or requirements in order to continueoperation, schedule maintenance or take immediate mainte-nance action.4. Summary of Test Method4.1 This test method uses FT-I
23、R spectrometry to monitornitration levels in in-service petroleum and hydrocarbon-basedlubricants. The FT-IR spectra of in-service oil samples arecollected according to the protocol for either direct trendanalysis or differential trend analysis described in PracticeD7418, and the levels of nitration
24、 are measured using the peakheight measurements described herein.5. Significance and Use5.1 There is a wide variety of nitration compounds that maybe produced and accumulate when oils react with gaseousnitrates formed during the engine combustion process. Thesenitration products may increase the vis
25、cosity, acidity andinsolubles in the oil, which may lead to ring sticking and filterplugging. Monitoring of nitration products is therefore animportant parameter in determining overall machinery healthand should be considered in conjunction with data from othertests such as atomic emission (AE) and
26、atomic absorption (AA)spectroscopy for wear metal analysis (Test Method D5185),physical property tests (Test Methods D445, D6304, andD2896), and other FT-IR oil analysis methods for oxidation(Test Method D7414), sulfate by-products (Test MethodD7415), additive depletion (Test Method D7412), and brea
27、k-down products and external contaminants (Practice E2412),which also assess elements of the oils condition. (1-6)6. Interferences6.1 Very high water levels can interfere with the nitrationmeasurement.6.2 Conjugated ketones, quinones, unsaturated carboxylicacids and carboxylic acid salts (formed due
28、 to the reaction ofacids with overbased oil additives) are also sources of inter-ference.6.3 Some aromatic compounds may interfere as well.7. Apparatus7.1 Fourier transform infrared spectrometer equipped withsample cell, filter (optional), and pumping system (optional) asspecified in Practice D7418.
29、7.2 FT-IR Spectral Acquisition ParametersSet FT-IRspectral acquisition parameters according to instructions inPractice D7418.8. Sampling8.1 Obtain a sample of the in-service oil and a sample of thereference oil (required only for differential trend analysis)according to the protocol described in Pra
30、ctice D7418.9. Preparation of Apparatus9.1 Rinse, flush, and clean the sample cell, inlet lines, andinlet filter according to instructions in Practice D7418.9.2 Monitor cell pathlength as specified in Practice D7418.10. Procedure10.1 Collect a background spectrum according to the pro-cedure specifie
31、d in Practice D7418.10.2 Differential Trend Analysis Only Collect the spec-trum of a reference oil sample, according to the procedurespecified in Practice D7418.10.3 Collect the spectrum of an in-service oil sampleaccording to the procedure specified in Practice D7418.10.4 Data ProcessingAll data ar
32、e normalized to a path-length of 0.100 mm according to the procedure specified inPractice D7418.11. Calculation of Nitration Values11.1 Procedure A (Direct Trend Analysis)Nitration by thedirect trending method is calculated from the oil samplespectrum using the measurement peak and baseline pointsli
33、sted in Table 1.11.2 Procedure B (Differential Trend Analysis)Nitrationby the differential trending method is calculated from thedifferential spectrum using the measurement peak and baselinepoints listed in Table 1. Fig. 1 illustrates the band used in themeasurement of nitration in the differential
34、spectrum of dieselcrankcase oil.11.3 Reporting:11.3.1 Procedure A (Direct Trend Analysis)Values arereported in units of absorbance per centimetre (Abs/cm),calculated as follows:D7624 102Nitration in Abs/cm 5 Nitration in Abs/0.100 mm * 100 (1)11.3.2 Procedure B (Differential Trend Analysis)Valuesare
35、 reported in units of absorbance per centimeter (Abs/cm),calculated as follows:Nitration in Abs/cm 5 Nitration in Abs/0.100 mm * 100 (2)11.4 Sample CarryoverTo ensure the minimum amount ofsample-to-sample cross-contamination or carryover, either aminimum volume of the subsequent sample or a solvent
36、rinseis used to flush out the previous sample. The efficacy of theflushing protocol may be assessed by consecutively analyzingan oil having a low (or zero) nitration level (L1, for example,a fresh oil) and a used oil sample having a high nitration level(H1) followed by a second run of the oil sample
37、 having a lownitration level (L2) and then calculating the percent carryover(PC) as follows:PC 5 L2L1!/H13100 (3)where L1, H1, and L2 are the values measured for nitration(using the parameters given in Table 1) for the samples run inthe indicated sequence. The calculated PC should be 5 %.12. Report1
38、2.1 TrendingData shall be recorded and reported atselected time intervals during the lubricants life. Ideally,nitration values would be compared to that of the newlyformulated oil and plotted over time to visualize the relativechanges in nitration and to determine when there needs to be anoil change
39、, albeit other parameters may dictate this changeearlier. Sampling and reporting time intervals for nitration arebased on the type of machinery and its previous historyassociated with this parameter.12.2 Statistical Analysis and Alarm LimitsFor statisticalanalysis and setting alarm limits, refer to
40、Practice E2412,Section A3, “Distribution Profiles and Statistical Analysis.”12.3 Effects of Oil FormulationThe compositions of vari-ous oil formulations can have an effect on the results reportedfor nitration value, and values from two different oil formula-tions should not be compared. Results shou
41、ld be interpretedrelative to values measured for unused oils of the sameformulation or trended directly from the sample history.13. Precision and Bias13.1 PrecisionThe precision of the test method has notyet been determined by a formal interlaboratory study. Prelimi-nary examinations of repeatabilit
42、y have shown that the differ-ence between repetitive results obtained by the same operatorin a given laboratory applying the same test method with theTABLE 1 Parameters for Measuring Nitration in In-Service Petroleum and Hydrocarbon Based LubricantsMethod Measurement, cm-1Baseline Point(s), cm-1Proc
43、edure A (Direct Trend Analysis) Height at 1630 Minima 1655 to 1640 and 1620 to 1595Procedure B (Differential Trend Analysis) Height at 1630 Minima 1655 to 1640 and 1620 to 1595FIG. 1 Nitration Measurement in the Differential Spectrum of a Petroleum Crankcase Lubricant for Differential Trend Analysis
44、(Procedure B)D7624 103same apparatus under constant operating conditions on identi-cal test material within short intervals of time would in the longrun, in the normal and correct operation of the test method,through the use of either Procedure A or Procedure B, exceedthe following value only in one
45、 case in 20:Repeatability r!50.078 absorbance units/cm for Procedures A and B(4)The reproducibility of this test method is being determined andwill be available on or before May 1, 2013.13.2 BiasThe procedures in this test method have no biasbecause the nitration values can be defined only in the te
46、rms ofthe test method and no accepted reference method or value isavailable.14. Keywords14.1 condition monitoring; differential trend analysis; directtrend analysis; Fourier transform infrared; FT-IR;hydrocarbon-based lubricants; infrared; in-service petroleumlubricants; IR; lubricants; nitration; oilsREFERENCES(1) Toms, L. A., and Toms, A. M. Machinery Oil Analysis: Methods,Automation or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D7624 104
