ASTM D7668 - 14

    Standard Test Method for Determination of Derived Cetane Number (DCN) of Diesel Fuel Oils—Ignition Delay and Combustion Delay Using a Constant Volume Combustion Chamber Method

    Active Standard ASTM D7668 | Developed by Subcommittee: D02.01.0C

    Book of Standards Volume: 05.05


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    ASTM D7668

    Significance and Use

    5.1 The ID and CD values and the DCN value determined by this test method provides a measure of the ignition characteristics of diesel fuel oil used in compression ignition engines.

    5.2 This test can be used by engine manufacturers, petroleum refiners and marketers, and in commerce as a specification aid to relate or match fuels and engines.

    5.3 The relationship of diesel fuel oil DCN determinations to the performance of full-scale, variable-speed, variable-load diesel engines is not completely understood.

    5.4 This test can be applied to non-conventional diesel fuels.

    5.5 This test determines ignition characteristics and requires a sample of approximately 370 mL and a test time of approximately 30 min using a fit-for-use instrument.

    1. Scope

    1.1 This test method covers the quantitative determination of the derived cetane number of conventional diesel fuel oils, diesel fuel oils containing cetane number improver additives, and is applicable to products typical of Specification D975, Grades No.1-D and 2-D regular, low and ultra-low-sulfur diesel fuel oils, European standard EN590, and Canadian standards CAN/CGSB-3.517 and CAN/CGSB3.6. The test method may be applied to the quantitative determination of the derived cetane number of biodiesel, blends of diesel fuel oils containing biodiesel material (for example, Specifications D975, D6751, and D7467), and diesel fuel oil blending components.

    1.2 This test method utilizes a constant volume combustion chamber with direct fuel injection into heated, compressed synthetic air. A dynamic pressure wave is produced from the combustion of the sample. An equation converts the ignition delay and the combustion delay determined from the dynamic pressure curve to a derived cetane number (DCN).

    1.3 This test method covers the ignition delay ranging from 1.9 to 25 ms and combustion delay ranging from 2.5 to 160 ms (30 to 70 DCN). However, the precision stated only covers the range of DCN from 39 to 67.

    1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

    1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D613 Test Method for Cetane Number of Diesel Fuel Oil

    D975 Specification for Diesel Fuel Oils

    D1193 Specification for Reagent Water

    D4057 Practice for Manual Sampling of Petroleum and Petroleum Products

    D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants

    D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products

    D5854 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products

    D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance

    D6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants

    D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material

    D6751 Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels

    D7467 Specification for Diesel Fuel Oil, Biodiesel Blend (B6 to B20)

    E456 Terminology Relating to Quality and Statistics

    EN Standards

    EN590 Automotive Fuels--Diesel--Requirements and Test Methods

    Energy Institute Standards

    IP41 Ignition Quality of Diesel Fuels--Cetane Engine Test Method

    Canadian Standards

    CAN/CGSB-3.517 Regular Sulphur Diesel Fuel--Specification

    CAN/CGSB3.6 Automotive Low-Sulphur Diesel Fuel--Specification


    ICS Code

    ICS Number Code 75.160.20 (Liquid fuels)

    UNSPSC Code

    UNSPSC Code 15101505(Diesel fuel)


    DOI: 10.1520/D7668

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