ASTM D1298 for density of crude petroleum and liquid petroleum products
ASTM D1298 for density of crude petroleum and liquid petroleum products by hydrometer method
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 density, n-the mass of liquid per unit volume at 15°C and 101.325 kPa with the standard unit of measurement being kilograms per cubic metre.
3.1.1.1 Discussion - Other reference temperatures, such as 20°C may be used for some products or in some locations. Less preferred units of measurement; for example, kg/L or g/mL are still in use.
3.1.2 relative density (specific gravity), n-the ratio of the mass of a given volume of liquid at a specific temperature to the mass of an equal volume of pure water at the same or different temperature. Both reference temperatures shall be explicitly stated.
3.1.2.1 Discussion - Common reference temperatures include 60/60°F, 20/20°C, 20/4°C. The historic deprecated term specific gravity may still be found.
3.1.3 API gravity, n-a special function of relative density (specific gravity) 60/60°F, represented by:
°API=141.5/(sp gr 60/60°F) - 131.5
3.1.3.1 Discussion - No statement of reference temperature is required, as 60°F is included in the definition.
3.1.4 observed values, n-values observed at temperatures other than the specified reference temperature. These values are only hydrometer readings and not density, relative density (specific gravity), or API gravity at that other temperature.
3.1.5 cloud point, n-temperature at which a cloud of wax crystals first appears in a liquid when it is cooled under specific conditions.
3.1.6 pour point, n-lowest temperature at which a test portion of crude petroleum or petroleum product will continue to flow when it is cooled under specified conditions.
3.1.7 wax appearance temperature (WAT), n-temperature at which waxy solids form when a crude petroleum or petroleum product is cooled under specified conditions.
