ASTM D287 standard test method for API gravity of crude petroleum and petroleum products(Hydrometer method)
6. Apparatus
6.1 Hydrometers, of glass, graduated in degrees API as listed in Table 1 and conforming to Specification E 100, or the IP Specifications for Petroleum Hydrometers.
6.2 Thermometers, having a range from -5 to + 215°F and conforming to the requirements for Thermometer 12F as prescribed in Specification E 1 or Thermometer 64F of the Specifications for IP Standard Thermometers. A thermometer is not required if a thermohydrometer is employed.
NOTE 2 - The ASTM Gravity Thermometer 12F has 0.5°F subdivisions and allowable more or less 0.25°F scale error. The thermometers incorporated in thermohydrometers have 2°F subdivisions and allowable more or less 1°F scale error.
6.3 Hydrometer Cylinders, of metal, clear glass, or plastic. For convenience in pouring, the cylinder may have a lip on the rim. The inside diameter of the cylinder shall be at least 25 mm greater than the outside diameter of the hydrometer used in it. The height of the cylinder shall be such that the length of the column of sample it contains is greater by at least 25 mm than the portion of the hydrometer which is immersed beneath the surface of the sample. For field testing, a sampling thief of suitable dimensions may be used.
7. Temperature of Test
7.1 The gravity determined by the hydrometer method is most accurate at or near the standard temperature of 60°F (15.56°C). Use this or any other temperature between 0 and 195°F (-18 and + 90°C) for the test, so far as it is consistent with the type of sample and necessary limiting conditions shown in Table 2.
