1、Designation: D976 06 (Reapproved 2016)Standard Test Method forCalculated Cetane Index of Distillate Fuels1This standard is issued under the fixed designation D976; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test method covers the Calculated
3、Cetane Indexformula, which represents a means for directly estimating theASTM cetane number of distillate fuels from API gravity andmid-boiling point. The index value, as computed from theformula, is termed the Calculated Cetane Index.21.2 The Calculated Cetane Index is not an optional methodfor exp
4、ressingASTM cetane number. It is a supplementary toolto estimate cetane number when used with due regard for itslimitations.1.3 The Calculated Cetane Index formula is particularlyapplicable to straight-run fuels, catalytically cracked stocks,and blends of the two.NOTE 1This test method is temporaril
5、y retained because the proposalto the U.S. EPA to control diesel fuel aromatics concentrations via a 40Calculated Cetane Index minimum is based on the correlation betweenTest Method D976 and aromatics concentration. Test Method D4737 is thepreferred method as estimator of cetane number.1.4 This stan
6、dard 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 health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 A
7、STM Standards:3D86 Test Method for Distillation of Petroleum Products andLiquid Fuels at Atmospheric PressureD287 Test Method for API Gravity of Crude Petroleum andPetroleum Products (Hydrometer Method)D613 Test Method for Cetane Number of Diesel Fuel OilD1298 Test Method for Density, Relative Densi
8、ty, or APIGravity of Crude Petroleum and Liquid Petroleum Prod-ucts by Hydrometer MethodD2887 Test Method for Boiling Range Distribution of Pe-troleum Fractions by Gas ChromatographyD4052 Test Method for Density, Relative Density, and APIGravity of Liquids by Digital Density MeterD4737 Test Method f
9、or Calculated Cetane Index by FourVariable Equation2.2 ASTM Adjuncts:4Nomograph for Calculated Cetane Index3. Significance and Use3.1 The Calculated Cetane Index is one tool available forestimating ASTM cetane number where a test engine is notavailable for determining this property. It may be employ
10、ed forapproximating cetane number where the quantity of sample istoo small for an engine rating. In cases where the cetanenumber of a fuel has been initially established, the index isuseful as a cetane number check on subsequent samples of thatfuel, provided its source and mode of manufacture remain
11、unchanged.3.2 Test Method D4737 may also be used to approximatethe ASTM cetane number of diesel fuels.3.2.1 Procedure A of Test Method D4737 was developed asa result of a larger degree of offset between Test Method D976Cetane Index and the results of Test Method D613 over theentire range of the corr
12、elation. Generally, it has been found thatuse of Test Method D4737 results in less offset than use of TestMethod D976, but there can be specific cases where this is nottrue.3.2.2 Procedure A of Test Method D4737 is recommendedto estimate the cetane number of diesel fuels with sulfurcontents above 50
13、0 ppm or No. 1D diesel fuels.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.E0 on Burner, Diesel, Non-Aviation Gas Turbine, and MarineFuels.Current edition approved April 1, 2016
14、. Published May 2016. Originallyapproved in 1966. Last previous edition approved in 2011 as D976 06 (2011).DOI: 10.1520/D0976-06R16.2A method of calculating cetane index was developed by the Diesel FuelsDivision, Coordinating Fuel and Equipment Research Committee of the Coordinat-ing Research Counci
15、l. See Young, H. D., “Methods for Estimating Cetane Number,”Proceedings, PPIRA, American Petroleum Institute, Vol. 30 M III, 1950. Thismethod was revised in 1960 by Research Division I of Committee D02 to conformto the revised Test Method D613.3For referenced ASTM standards, visit the ASTM website,
16、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.4Available from ASTM International Headquarters. Order Adjunct No.ADJD0976. Original adjunct produced in 1989.Copyrig
17、ht ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.3 Procedure B of Test Method D4737 is recommendedto estimate the cetane number of No. 2D diesel fuels withsulfur contents at or below 500 ppm.3.3 Calculated Cetane Index, as described in Te
18、st MethodD97680, is recognized by the United States EPA as analternative method to meet the U.S. Federal Diesel aromaticslimit for diesel fuels containing less than 500 ppm sulfur. Theequation for Calculated Cetane Index in Test Method D97680and in this version (D97606) of the test method are the sa
19、me.4. Equation for Calculated Cetane Index4.1 The Calculated Cetane Index is determined from thefollowing equation:Calculated cetane index 52420.3410.016 G210.192 G log M (1)165.01 log M!22 0.0001809 M2orCalculated cetane index 5 454.74 2 1641.416 D1774.74 D2(2)20.554 B197.803 log B!2where:G = API g
20、ravity, determined by Test Method D287, D1298,or D4052,M = mid-boiling temperature, F, determined by TestMethod D86 and corrected to standard barometricpressure,D = density at 15 C, g/mL, determined by Test MethodD1298 or D4052, andB = mid-boiling temperature, C, determined by TestMethod D86 and cor
21、rected to standard barometricpressure.4.2 Calculated Cetane Index values for distillate fuels maybe conveniently determined by means of the alignment chart inFig. 1 rather than by direct application of the equation. Use ofthe chart is illustrated by the example shown on the chart.4.3 Test Method D28
22、87 may be used as an alternative toTest Method D86 to determine the mid-boiling temperature ofthe fuel.4.3.1 If Test Method D2887 is used, convert the data toestimated Test Method D86 data following Appendix X5,Correlation of Jet and Diesel Fuel of test Method D2887 anduse the data from Test Method
23、D86 in place of the actual TestMethod D86 data in the calculations.NOTE 2Current U.S. EPA regulations for low sulfur (500 ppmmaximum) No. 1D and No. 2D diesel fuel require the use of TestMethod D97680 to calculate Cetane Index.5. Limitations of Equation5.1 The Calculated Cetane Index equation posses
24、ses certaininherent limitations which must be recognized in its applica-tion. These are:5.1.1 It is not applicable to fuels containing additives forraising cetane number.5.1.2 It is not applicable to pure hydrocarbons, syntheticfuels, such as certain products derived from shale oils and tarsands, al
25、kylates, or coal-tar products.5.1.3 Substantial inaccuracies in correlation may occur ifused for crude oils, residuals, or products having a volatility ofbelow 500 F end point.6. Report6.1 Round and report the calculated cetane index to thenearest tenth. Any calculated cetane index value ending inex
26、actly “5” in the second decimal place shall be rounded to thenearest even tenth number. For example, round “35.55” and“35.65” to “35.6 cetane index.”7. Precision and Bias7.1 Correlation of index values with ASTM cetane numberis dependent to a great extent upon the accuracy of determi-nation of both
27、API gravity and midboiling point.7.2 Within the range from 30 to 60 cetane number, theexpected correlation of the Calculated Cetane Index with theASTM cetane number will be somewhat less than 62 cetanenumbers for 75 % of the distillate fuels evaluated. Errors incorrelation may be greater for fuels w
28、hose cetane numbers areoutside this range. Correlation is best for straight-run andcatalytically cracked distillates and blends of the two, and leastsatisfactory for blends containing substantial proportions ofthermally cracked stocks.8. Keywords8.1 cetane; cetane index; diesel fuelD976 06 (2016)2AS
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33、 at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 1The Calculated
34、 Cetane Index equation represents a useful tool for estimating cetane number. Due to inherent limitations in the equationsapplication, Index values may not be a valid substitute for ASTM cetane numbers as determined in a test engine.FIG. 1 Nomograph for Calculated Cetane Index (ECS-1 Meter BasisTest Method D613)D976 06 (2016)3
