ASTM D7061 - 12

    Standard Test Method for Measuring n-Heptane Induced Phase Separation of Asphaltene-Containing Heavy Fuel Oils as Separability Number by an Optical Scanning Device

    Active Standard ASTM D7061 | Developed by Subcommittee: D02.14

    Book of Standards Volume: 05.04


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    Significance and Use

    5.1 This procedure describes a rapid and sensitive method for estimating the stability reserve of an oil. The stability reserve is estimated in terms of a separability number, where a low value of the separability number indicates that there is a stability reserve within the oil. When the separability number is between 0 to 5, the oil can be considered to have a high stability reserve and asphaltenes are not likely to flocculate. If the separability number is between 5 to 10, the stability reserve in the oil will be much lower. However, asphaltenes are, in this case, not likely to flocculate as long as the oil is not exposed to any worse conditions, such as storing, aging, and heating. If the separability number is above 10, the stability reserve of the oil is very low and asphaltenes will easily flocculate, or have already started to flocculate.

    5.2 This test method can be used by refiners and users of oils, for which this test method is applicable, to estimate the stability reserves of their oils. Hence, this test method can be used by refineries to control and optimize their refinery processes. Consumers of oils can use this test method to estimate the stability reserve of their oils before, during, and after storage.

    Schematic Representation of a Typical Measurement Using
an Optical Scanning Device
    FIG. 1 Schematic Representation of a Typical Measurement Using an Optical Scanning Device

    5.3 This test method is not intended for predicting whether oils are compatible before mixing, but can be used for determining the separability number of already blended oils. However, oils that show a low separability number are more likely to be compatible with other oils than are oils with high separability numbers.

    1. Scope

    1.1 This test method covers the quantitative measurement, either in the laboratory or in the field, of how easily asphaltene-containing heavy fuel oils diluted in toluene phase separate upon addition of heptane. This is measured as a separability number (%) by the use of an optical scanning device.

    1.2 The test method is limited to asphaltene-containing heavy fuel oils. ASTM specification fuels that generally fall within the scope of this test method are Specification D396, Grade Nos. 4, 5, and 6, Specification D975, Grade No. 4-D, and Specification D2880, Grade Nos. 3-GT and 4-GT. Refinery fractions from which such blended fuels are made also fall within the scope of this test method.

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

    1.4 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

    D396 Specification for Fuel Oils

    D975 Specification for Diesel Fuel Oils

    D2880 Specification for Gas Turbine Fuel Oils

    D4057 Practice for Manual Sampling of Petroleum and Petroleum Products

    D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products


    ICS Code

    ICS Number Code 71.080.10 (Aliphatic hydrocarbons)

    UNSPSC Code

    UNSPSC Code 15101702(#4 or #6 Residual heavy fuel oils)


    DOI: 10.1520/D7061-12

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