API MPMS Chapter 9.3

This test method covers the determination, using a glass thermohydrometer and/or a separate (alternative) temperature measuring device in conjunction with a series of calculations, of the density, relative density, or API gravity of crude petroleum, petroleum products, or mixtures of petroleum and nonpetroleum products normally handled as liquids and having Reid vapor pressures of 101.325 kPa (14.696 psia) or less. Values are determined at existing temperatures and corrected to 15 °C (or 60 °F) by means of a series of calculations and international standard tables. Alternative temperature measuring devices shall be either the appropriate liquid-in-glass ASTM thermometers meeting either Specifications E1 or E2251 or digital contact thermometers.