ASTM D2140 for carbon-type composition of insulating oils
ASTM D2140 standard test method for carbon-type composition of insulating oils of petroleum origin
1. Scope
1.1 This test method 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 test method 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 test method 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 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
2.1 ASTM Standards:
D129 Test Method for Sulfur in Petroleum Products (General Bomb Method)
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and the 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 and Relative Density of Liquids by Digital Density Meter
3. Terminology
3.1 Definitions:
3.1.1 percent of aromatic carbons (% CA) - the weight percent of the total carbon atoms present in an oil that are combined in aromatic ring-type structures.
3.1.2 percent of naphthenic carbons (% CN) - the weight percent of the total carbon atoms present in an oil that are combined in naphthenic ring-type structures.
3.1.3 percent of paraffinic carbons (% CP) - the weight percent of the total carbon atoms present in an oil that are combined in paraffinic chain-type structures.
NOTE 1 - The resolution of carbon atoms into structural classifications is independent of whether the structures exist as separate molecules or are combined with other structural forms in a molecule. For example, a paraffinic chain may be either an aliphatic hydrocarbon molecule, or may be an alkyl group attached to an aromatic or naphthenic ring.
