Designation: D976 – 06
Standard Test Method for
Calculated Cetane Index of Distillate Fuels 1 This standard is issued under the fixed designation D976; the number immediately following the designation indicates the year of original origin al adoption or, in the case of revis revision, ion, the year of last revision. revision. A number in paren parenthese thesess indicates the year of last reappr reapproval. oval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense.
D287 Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method) D613 Test Method for Cetane Number of Diesel Fuel Oil D1298 Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method D2887 Tes Testt Me Meth thod od fo forr Bo Boili iling ng Ra Rang ngee Di Dist stri ribu buti tion on of Petroleum Petro leum Fractio Fractions ns by Gas Chrom Chromatogra atography phy D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter D4737 Test Method for Calculated Cetane Index by Four Variable Equation 2.2 ASTM Adjuncts:4 Nomograph for Calculated Cetane Index
1. Sco Scope* pe* 1.1 Thi Thiss tes testt met method hod covers covers the Calculated Calculated Cetane Index formula, which represents a means for directly estimating the ASTM cetane number of distillate fuels from API gravity and mid-bo mid -boilin iling g poi point. nt. The ind index ex valu value, e, as com comput puted ed fro from m the formula, is termed the Calculated Cetane Index.2 1.2 The Calculated Calculated Cetane Index is not an optional optional method for expressing ASTM cetane number. number. It is a supplementary tool to estimate cetane number when used with due regard for its limitations. 1.3 The Calc Calcula ulated ted Ceta Cetane ne Ind Index ex for formul mulaa is par particu ticular larly ly applicable applica ble to straig straight-ru ht-run n fuels, catalytically cracked stocks stocks,, and blends of the two. NOTE 1—This test method is temporarily retained because the proposal to the U.S. EPA to control diesel fuel aromatics concentrations via a 40 Calculated Cetane Index minimum is based on the correlation between Test Method D976 and aromatics concentration. Test Method D4737 Method D4737 is is the preferred prefer red method as estim estimator ator of cetane number. number.
3. Signi Significanc ficancee and Use 3.1 The Calculate Calculated d Ceta Cetane ne Ind Index ex is one tool available available for estimating ASTM cetane number where a test engine is not available for determining this property. It may be employed for approximating cetane number where the quantity of sample is too to o sm smal alll fo forr an en engi gine ne ra ratin ting. g. In ca case sess wh wher eree th thee ce cetan tanee number of a fuel has been initially established, the index is useful as a cetane number check on subsequent samples of that fuel, fue l, pro provid vided ed its sou source rce and mod modee of man manufa ufactu cture re rem remain ain unchanged. 3.2 Test Method D4737 Method D4737 may also be used to approximate the ASTM cetane number of diesel fuels. 3.2.1 Proce Procedure dure A of Test Test Method D4737 Method D4737 was was developed as a result of a larger degree of offset between Test Method D976 Cetane Index and the results of Test Method D613 over the entire range of the correlation. Generally, it has been found that use of Test Method D4737 Method D4737 results results in less offset than use of Test Method D976, but there can be specific cases where this is not true. 3.2.2 Proce Procedure dure A of Test Test Metho Method d D4737 is recommended to es estim timate ate th thee ce cetan tanee nu numb mber er of di dies esel el fu fuels els wi with th su sulf lfur ur contents above 500 ppm or No. 1–D diesel fuels. 3.2.3 Proce Procedure dure B of Test Test Method D4737 Method D4737 is recommended to estimate the cetane number of No. 2–D diesel fuels with sulfur contents at or below 500 ppm.
standard d doe doess not purport purport to add addre ress ss all of the 1.4 This standar safet sa fetyy co conc ncer erns ns,, if an anyy, as asso socia ciate ted d wi with th its us use. e. It is th thee responsibility of the user of this standard to establish appro priate safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenc Referenced ed Documents Documents 2.1 ASTM Standards:3 D86 Test Method for Distillation of Petroleum Products at Atmospheric Pressure
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Thiss tes Thi testt met method hod is und under er the juri jurisdi sdicti ction on of AST ASTM M Com Commit mittee tee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.E0.02 on D02.E0.02 on Diesel Fuel Oils. Current Curre nt editio edition n appro approved ved Dec. 1, 2006. Published Published Janua January ry 2007. Originally Originally approved in 1966. Last previous edition approved in 2004 as D976–04b 1. DOI: 10.1520/D0976-06. 2 A met method hod of cal calcul culati ating ng cet cetane ane index was develope developed d by the Die Diesel sel Fuels Division, Coordinating Fuel and Equipment Research Committee of the Coordinating Research Council. See Young, H. D., “Methods for Estimating Cetane Number,” Proceedings, PPIRA, PPIRA, American Petroleum Petroleum Insti Institute, tute, Vol. Vol. 30 M [III], 1950. This method was revised revised in 1960 by Research Division Division I of Committee D02 to conform to the revised Test Method D613 Method D613.. 3 For refere referenced nced ASTM stand standards, ards, visit the ASTM websi website, te, www www.astm .astm.org .org,, or contact ASTM Customer Service at
[email protected]. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website. ´
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Availab Av ailable le from ASTM Inter Internatio national nal Head Headquart quarters. ers. Order Adjunct No. ADJD0976. Original adjunct produced in 1989.
*A Summary of Changes section appears at the end of this standard. Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D976 – 06 3.3 Calcula Calculated ted Cetane Index, as descr described ibed in Test Method D976 D9 76–8 –80, 0, is re reco cogn gnize ized d by th thee Un Unite ited d St State atess EP EPA A as an alternative method to meet the U.S. Federal Diesel aromatics limit for diesel fuels containing less than 500 ppm sulfur. The equation for Calculated Cetane Index in Test Method D976–80 and in this version (D976–06) of the test method are the same.
NOTE 2—Cu 2—Curre rrent nt U. U.S. S. EP EPA A reg regula ulatio tions ns for low sul sulfur fur (50 (500 0 ppm maximum) maximu m) No. 1–D and No. 2–D diesel fuel require require the use of Test Test Method D976–80 to calculate Cetane Index.
5. Limi Limitati tations ons of Equat Equation ion 5.1 The Calculated Cetane Cetane Index equation possesses possesses certain inherent limitations which must be recognized in its application. These are: 5.1.1 5.1 .1 It is not applicabl applicablee to fue fuels ls con contain taining ing additives additives for raising cetane number. 5.1.2 5.1 .2 It is not app applica licable ble to pur puree hyd hydroc rocarb arbons ons,, syn synthe thetic tic fuels, such as certain products derived from shale oils and tar sands, alkylates, or coal-tar products. 5.1.3 5.1 .3 Sub Substan stantial tial inac inaccur curacie aciess in cor correla relatio tion n may occ occur ur if used for crude oils, residuals, or products having a volatility of below 500°F end point.
4. Equa Equation tion for Calculated Calculated Cetane Index 4.1 The Calculated Calculated Cetane Cetane Ind Index ex is det determ ermine ined d fro from m the following equation: Calculated cetane index 5 2420.34 1 0.016 G 2 1 0.192 G log M
1 65.01 ~log M !2 2 0.0001809 M 2
(1)
or Calculated cetane index 5 454.74 2 1641.416 D 1 774.74 D 2
20.554 B 1 97.803 ~log B !2
(2)
6. Repor Reportt
where: G = AP APII gr grav avit ity y, de deter termi mine ned d by Tes estt Me Meth thod od D287, D287, D1298,, or D1298 or D4052 D4052,, mid-bo -boilin iling g tem temper peratu ature, re, °F °F,, det determ ermine ined d by Test M = mid Method D86 and cor correc rected ted to stan standar dard d bar barome ometric tric pressure, D = den density sity at 15° 15°C, C, g/mL, determin determined ed by Test Method Method D1298 or or D4052 D4052,, and mid-b -boil oiling ing tem temper peratu ature, re, °C, det determ ermine ined d by Test B = mid Method D86 and cor correc rected ted to stan standar dard d bar barome ometric tric pressure. 4.2 Calcula Calculated ted Cetane Index values for distillate distillate fuels may be conveniently determined by means of the alignment chart in Fig. 1 rather 1 rather than by direct application of the equation. Use of the chart is illustrated by the example shown on the chart. 4.3 Test Method D2887 may be used as an alternative to Test Method D86 Method D86 to determine the mid-boiling temperature of the fuel. 4.3.1 4.3 .1 If Test Met Method hod D2887 is us used ed,, co conv nver ertt th thee da data ta to estimat esti mated ed Test Met Method hod D86 data follow following ing Appen Appendix dix X5, Correlation of Jet and Diesel Fuel of test Method D2887 and use the data from Test Method D86 Method D86 in place of the actual Test Method D86 D86 data data in the calculations.
6.1 Round and rep report ort the calc calcula ulated ted cetane index to the neares nea restt tent tenth. h. Any calc calcula ulated ted ceta cetane ne ind index ex val value ue end ending ing in exactly “5” in the second decimal decimal place shall be rounded to the nearest even tenth number. For example, round “35.55” and “35.65” to “35.6 cetane index.” 7. Pre Precisi cision on and Bias 7.1 Correl Correlation ation of index values with ASTM cetane number is dependent to a great extent upon the accuracy of determination of both API gravity and midboiling point. 7.2 7. 2 With ithin in th thee ra rang ngee fr from om 30 to 60 ce cetan tanee nu numb mber er,, th thee expected correlation of the Calculated Cetane Index with the ASTM cetane number will be somewhat less than 62 cetane numbers for 75 % of the distillate fuels evaluated. Errors in correlation may be greater for fuels whose cetane numbers are outsid out sidee thi thiss ran range. ge. Cor Correla relatio tion n is bes bestt for str straig aightht-run run and catalytically cracked distillates and blends of the two, and least satisfactory satisfa ctory for blend blendss contain containing ing subst substantial antial proportions proportions of thermally therma lly cracke cracked d stocks stocks.. 8. Keyw Keywords ords 8.1 cetane; cetane cetane index; diesel fuel
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D976 – 06
NOTE—The Calculated Cetane Index equation represents a useful tool for estimating cetane number. Due to inherent limitations in the equation’s application, Index values may not be a valid substitute for ASTM cetane numbers as determined in a test engine. FIG. 1 Nomo Nomograph graph for Calcul Calculated ated Cetane Index (ECS(ECS-1 1 Meter Basis—Test Basis—Test Method D613 D613))
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D976 – 06 SUMMARY OF CHANGES Subcommittee D02.E0 has identified the location of selected changes to this standard since the last issue (D976–04b 1) that may impact the use of this standard. ´
(1) Rev Revised ised 1.2 1.2.. (2) Rev Revised ised 3.1 3.1..
(3) Add Added ed 3.2-3.3 3.2-3.3..
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