ASTM D2140 - 08

    Standard Practice for Calculating Carbon-Type Composition of Insulating Oils of Petroleum Origin

    Active Standard ASTM D2140 | Developed by Subcommittee: D27.07

    Book of Standards Volume: 10.03


      Format Pages Price  
    PDF Version 4 $37.00   ADD TO CART
    Print Version 4 $37.00   ADD TO CART
    Standard + Redline PDF Bundle 8 $44.40   ADD TO CART


    Significance and Use

    The primary purpose of this practice is to characterize the carbon-type composition of an oil. It is also applicable in observing the effect on oil constitution, of various refining processes such as hydrotreating, solvent extraction, and so forth. It has secondary application in relating the chemical nature of an oil to other phenomena that have been demonstrated to be related to oil composition.

    Results obtained by this practice are similar to, but not identical with, results obtained from Test Method D 3238. The relationship between the two and the equations used in deriving Fig. 1 are discussed in the literature.

    Although this practice tends to give consistent results, it may not compare with direct measurement test methods such as Test Method D 2007.

    1. Scope

    1.1 This practice may be used to determine the carbon-type composition of mineral insulating oils by correlation with basic physical properties. For routine analytical purposes it eliminates the necessity for complex fractional separation and purification procedures. The practice is applicable to oils having average molecular weights from 200 to above 600, and 0 to 50 aromatic carbon atoms.

    1.2 Carbon-type composition is expressed as percentage of aromatic carbons, percentage of naphthenic carbons, and percentage of paraffinic carbons. These values can be obtained from the correlation chart, Fig. 1, if both the viscosity-gravity constant (VGC) and refractivity intercept (ri) of the oil are known. Viscosity, density and relative density (specific gravity), and refractive index are the only experimental data required for use of this test method.

    1.3 This practice is useful for determining the carbon-type composition of electrical insulating oils of the types commonly used in electric power transformers and transmission cables. It is primarily intended for use with new oils, either inhibited or uninhibited.

    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.


    FIG. 1 Correlation Chart for Determining % CA, % CN, and % CP


    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

    D129 Test Method for Sulfur in Petroleum Products (General High Pressure Decomposition Device Method)

    D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)

    D923 Practices for Sampling Electrical Insulating Liquids

    D1218 Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon Liquids

    D1481 Test Method for Density and Relative Density (Specific Gravity) of Viscous Materials by Lipkin Bicapillary Pycnometer

    D2007 Test Method for Characteristic Groups in Rubber Extender and Processing Oils and Other Petroleum-Derived Oils by the Clay-Gel Absorption Chromatographic Method

    D2501 Test Method for Calculation of Viscosity-Gravity Constant (VGC) of Petroleum Oils

    D3238 Test Method for Calculation of Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M Method

    D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter


    ICS Code

    ICS Number Code 29.040.10 (Insulating oils)

    UNSPSC Code

    UNSPSC Code 15121505(Transformer oil or insulating oil)


    DOI: 10.1520/D2140-08

    ASTM International is a member of CrossRef.

    ASTM D2140

    Citing ASTM Standards
    Back to Top