ASTM D7261 - 13

    Standard Test Method for Determining Water Separation Characteristics of Diesel Fuels by Portable Separometer

    Active Standard ASTM D7261 | Developed by Subcommittee: D02.14

    Book of Standards Volume: 05.04


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    Significance and Use

    5.1 This test method provides a measure of the presence of surfactants in diesel fuels, and can be performed in the field or in a laboratory. Like Test Method D3948 used for jet fuel, this test method can detect traces of some refinery treating chemicals left in fuel. It can also detect surface active substances added to or picked up by the fuel during handling from point of production to point of use.

    5.2 Certain additives, which can act as weak surfactants, give a slightly reduced DSEP rating. Other substances which are strong surfactants give much lower DSEP ratings.

    5.3 While filter separators have not been common in diesel fuel systems, they could become more prevalent with ULSD containing increased additive content to ensure clean, dry fuels in new engine designs. Weak surfactants, with slightly reduced DSEP ratings, do not affect the ability of filter separators to separate free water from the fuel. Strong surfactants give a much lower DSEP rating and adversely affect the ability of filter separators to separate free water from the fuel.

    5.4 Results from this test method do not have a known relationship to the rate of water settling in tanks.

    5.5 The Micro-Separometer instrument has a measurement range from 50 to 100. Values obtained outside of those limits are undefined and invalid.

    Note 2In the event a value greater than 100 is obtained, there is a good probability that light transmittance was reduced by material contained in the fuel used to set the 100 reference level. The material was subsequently removed during the coalescing portion of the test, thus, the processed fuel had a higher light transmittance than the fuel sample used to obtain the 100 reference level resulting in the final rating measuring in excess of 100.

    1. Scope

    1.1 This test method covers a rapid portable means for field and laboratory use to rate the ability of diesel fuels (both neat and those containing additives) to release entrained or emulsified water when passed through fiberglass coalescing material.

    1.2 This test method is applicable to diesel fuels such as D975 Grade No. 1 and Grade No. 2 of all sulfur levels, and MIL-F-16884, naval distillate fuel (NATO F-76).

    Note 1This test method is similar to Test Method D3948 which is applicable to aviation turbine fuels.

    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

    D975 Specification for Diesel Fuel Oils

    D1193 Specification for Reagent Water

    D3948 Test Method for Determining Water Separation Characteristics of Aviation Turbine Fuels by Portable Separometer

    D4057 Practice for Manual Sampling of Petroleum and Petroleum Products

    D4176 Test Method for Free Water and Particulate Contamination in Distillate Fuels (Visual Inspection Procedures)

    D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products

    D4306 Practice for Aviation Fuel Sample Containers for Tests Affected by Trace Contamination

    D4860 Test Method for Free Water and Particulate Contamination in Middle Distillate Fuels (Clear and Bright Numerical Rating)

    D6426 Test Method for Determining Filterability of Middle Distillate Fuel Oils

    D7224 Test Method for Determining Water Separation Characteristics of Kerosine-Type Aviation Turbine Fuels Containing Additives by Portable Separometer

    Military Standard

    MIL-F-16884 Fuel, Naval Distillate (NATO F-76) Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.


    ICS Code

    ICS Number Code 75.160.20 (Liquid fuels)

    UNSPSC Code

    UNSPSC Code 15101505(Diesel fuel)


    DOI: 10.1520/D7261-13

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