An American National Standard
Standard Test Method for
API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method)1
This standard is issued under the ﬁxed designation D 287; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number inparentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. This test method has been adopted for use by government agencies to replace Method 401 of Federal Test Method Standard No. 791b.
e1 NOTE—Editorial corrections were made throughout in April 2000.
1. Scope 1.1 This test method covers thedetermination by means of a glass hydrometer of the API gravity of crude petroleum and petroleum products normally handled as liquids and having a Reid vapor pressure (Test Method D 323) of 26 psi (180 kPa) or less. Gravities are determined at 60°F (15.56°C), or converted to values at 60°F, by means of standard tables. These tables are not applicable to nonhydrocarbons or essentially pure hydrocarbons such asthe aromatics.
NOTE 1—The international version of this test method is described in Practice D 1298.
E 100 Speciﬁcation for ASTM Hydrometers3 2.2 IP Standards:4 Speciﬁcations for IP Standard Thermometers IP Speciﬁcations for Petroleum Hydrometers 3. Terminology 3.1 Deﬁnitions: 3.1.1 API gravity—a special function of relative density (speciﬁc gravity) 60/60°F (15.56/15.56°C), represented by:API gravity, deg 5 ~141.5/sp gr 60/60°F! 2 131.5 (1)
1.2 Values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are provided for information purposes only. 1.3 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 safetyand health practices and determine the applicability of regulatory limitations prior to use. For speciﬁc hazard statements, see 8.3. 2. Referenced Documents 2.1 ASTM Standards: D 323 Test Method for Vapor Pressure of Petroleum Products (Reid Method)2 D 1250 Guide for Petroleum Measurement Tables2 D 1298 Practice for Density, Relative Density (Speciﬁc Gravity), or API Gravity of Crude Petroleum andLiquid Petroleum Products by Hydrometer Method2 E 1 Speciﬁcation for ASTM Thermometers3
No statement of reference temperature is required, since 60°F is included in the deﬁnition. 4. Summary of Test Method 4.1 This test method is based on the principle that the gravity of a liquid varies directly with the depth of immersion of a body ﬂoating in it. The ﬂoating body, which is graduated by APIgravity units in this method, is called an API hydrometer. 4.2 The API gravity is read by observing the freely ﬂoating API hydrometer and noting the graduation nearest to the apparent intersection of the horizontal plane surface of the liquid with the vertical scale of the hydrometer, after temperature equilibrium has been reached. The temperature of the sample is read from a separate accurate ASTMthermometer in the sample or from the thermometer which is an integral part of the hydrometer (thermohydrometer). 5. Signiﬁcance and Use 5.1 Accurate determination of the gravity of petroleum and its products is necessary for the conversion of measured volumes to volumes at the standard temperature of 60°F (15.56°C). 5.2 Gravity is a factor governing the quality of crude oils. However, the gravityof a petroleum product is an uncertain
1 This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants, and is the direct responsibility of Subcommittee D02.04 on Hydrocarbon Analysis. Current edition adopted Aug. 15, 1992. Published October 1992. Originally published as D 287 – 28 T, replacing former D 47. Last previous edition D 287 – 82 (1987) e1. 2...