Norma Astm D287

An American National Standard

Designation: D 287 – 92 (Reapproved 2000)e1

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 numberin parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense. 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 weremade throughout in April 2000.

2.2 IP Standards:4
Specifications for IP Standard Thermometers
IP Specifications for Petroleum Hydrometers

1. Scope
1.1 This test method covers the determination 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)
orless. 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 as the aromatics.

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)

NOTE 1—The international version of this test method is described in
Practice D 1298.

No statement of reference temperature is required, since
60°F is included in the definition.

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 notpurport 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. For specific hazard
statements, see 8.3.

4. Summary of Test Method
4.1 This test method is based on the principle that the
gravity of aliquid varies directly with the depth of immersion
of a body floating in it. The floating body, which is graduated
by API gravity 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 thehydrometer, after temperature equilibrium has been reached. The temperature of the
sample is read from a separate accurate ASTM thermometer in
the sample or from the thermometer which is an integral part of
the hydrometer (thermohydrometer).

2. Referenced Documents
2.1 ASTM Standards:
D 323 Test Method for Vapor Pressure of Petroleum Products (Reid Method)2
D 1250 Guide for PetroleumMeasurement Tables2
D 1298 Practice for Density, Relative Density (Specific
Gravity), or API Gravity of Crude Petroleum and Liquid
Petroleum Products by Hydrometer Method2
E 1 Specification for ASTM Thermometers3
E 100 Specification for ASTM Hydrometers3

5. Significance and Use
5.1 Accurate determination of the gravity of petroleum and
its products is necessary for the conversion of measuredvolumes 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 gravity of a petroleum product is an uncertain
indication of its quality. Correlated with other properties,

1
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of...