ASTM D7777 - Density
Significance and Use
5.1 The density, relative density, or API gravity of petroleum products are important quality indicators and are used in quantity calculations or to satisfy application, transportation, storage, and regulatory requirements.
5.2 This test method should not be used to determine density for custody transfer quantity calculations, particularly where mass or weight is the unit of quantity measurement. Test Method D4052 is appropriate for these applications.
1.1 This test method covers the determination of the density, relative density, or API gravity of liquid petroleum products using portable digital density meters at test temperatures between 0 and 40°C (32 to 104°F). Its application is restricted to samples with a dry vapor pressure equivalent up to 80 kPa (11.6 psi) and a viscosity below 100 mm2/s (cSt) at the test temperature.
1.2 This test method is suitable for determining the density to the nearest 1 kg/m3. To determine the density to the nearest 0.1 kg/m3, use Test Method D4052.
1.3 This test method is easily calibrated and primarily suitable for field applications. It is important for the user to know and understand the electrical classification of the area in which the analyzer is to be used and to select an analyzer appropriate for that classification.
1.4 Test Methods D287, D1298, and D6822 are used in field applications. This test method provides an alternative field method that is easily calibrated and does not pose the hazard of hydrometer glass breakage present in current field methods.
1.5 Portable digital density meters measure the density and temperature of the filled-in sample at the sample temperature. The measured density and temperature are automatically converted into:
Density at 15C / density at 60F
Relative density 15C/15C / relative density 60F/60F
API gravity 15C / API gravity 60F
by the instrument using the calculation routines for Generalized Products as defined in Guide D1250.
1.6 If the density meter does not have in-built software to calculate the density at the reference temperature, this is calculated from the observed density at test temperature using the Petroleum Measurement Tables.
1.7 The accepted units of measure for density are kilograms per cubic metre (SI unit) or grams per cubic centimetre. Values in SI units are to be regarded as the standard. Values in parentheses are for information only. Both SI and customary units have been rounded; they may not be exactly equivalent.
1.8 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 safety and health practices and determine the applicability of regulatory limitations prior to use.
Extracted, with permission, from ASTM D7777 - 13 Standard Test Method for Density, Relative Density, or API Gravity of Liquid Petroleum by Portable Digital Density Meter, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard may be purchased from ASTM International, astm.org