ASTM D1657 Test Method for Density or Relative Density of Light Hydrocarbons by Pressure Hydrometer
1. Scope
1.1 This test method covers the determination of the density or relative density of light hydrocarbons including liquefied petroleum gases (LPG) having Reid vapor pressures exceeding 101.325 kPa (14.696 psi).
1.2 The prescribed apparatus should not be used for materials having vapor pressures higher than 1.4 MPa (200 psi) at the test temperature. This pressure limit is dictated by the type of equipment. Higher pressures can apply to other equipment designs.
1.3 The initial pressure hydrometer readings obtained are uncorrected hydrometer readings and not density measurements. Readings are measured on a hydrometer at either the reference temperature or at another convenient temperature, and readings are corrected for the meniscus effect, the thermal glass expansion effect, alternate calibration temperature effects and to the reference temperature by means of calculations and Adjunct to D1250 Guide for Petroleum Measurement Tables (API MPMS Chapter 11.1) or API MPMS Chapter 11.2.4 (GPA TP-27), as applicable.
1.4 Values determined as density or relative density can be converted to equivalent values in the other units or alternative reference temperatures by means of Interconversion Procedures API MPMS Chapter 11.5, or Adjunct to D1250 Guide for Petroleum Measurement Tables (API MPMS Chapter 11.1) or API MPMS Chapter 11.2.4 (GPA TP-27), as applicable.
1.5 The calculations required in Section 11 shall be applied to the initial pressure hydrometer reading with observations and results reported as required by Section 11 prior to use in a subsequent calculation procedure (measurement ticket calculation, meter factor calculation, or base prover volume determination).
1.6 Annex A1 contains a procedure for verifying or certifying the equipment for this test method.
1.7 The values in SI units are to be regarded as the standard. US Customary values shown in adjacent parentheses are for information only and may not be exactly equivalent. Both SI and customary units have been rounded so that 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.
2. Referenced Documents
2.1 ASTM Standards:
D1250 Guide for Use of the Petroleum Measurement Tables
D1265 Practice for Sampling Liquefied Petroleum (LP) Gases, Manual Method
D1298 Test Method for Density, Relative Density, and API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method (API MPMS Chapter 9.1)
E1 Specification for ASTM Liquid-in-Glass Thermometers
E100 Specification for ASTM Hydrometers
2.2 API Standards:
MPMS Chapter 9.1 Test Method for Density, Relative Density, and API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method (ASTM Test Method D1298)
MPMS Chapter 11.1 Temperature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined Products and Lubricating Oils (Adjunct to ASTM D1250)
MPMS Chapter 11.2.2 Compressibility Factors for Hydrocarbons: 0.350-0.0637 Relative Density (60°F/60°F) and -50°F to 140°F Metering Temperature
MPMS Chapter 11.2.2M Compressibility Factors for Hydrocarbons: 350-637 Kilograms per Cubic Meter Density 15°C and -46°C to 60°C Metering Temperatures
MPMS Chapter 11.2.4 Temperature Correction for the Volume of NGL and LPG Tables 23E, 24E, 53E, 54E, 59E and 60E (joint standard with GPA TP-27)
MPMS Chapter 11.5 Density/Weight/Volume Intraconversion
2.3 GPA Standards:
GPA Technical Publication TP-27 Temperature Correction for the Volume of NGL and LPG, Tables 23E, 24E, 53E, 54E, 59E and 60E (joint standard with API MPMS Chapter 11.2.4)
2.4 ASTM Adjuncts:
Adjunct to D1250 Guide for Petroleum Measurement Tables (API MPMS Chapter 11.1)
3. Terminology
3.1 Definitions:
3.1.1 density, n - the mass of liquid per unit volume at 15°C and its saturation pressure 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 thermohydrometer, n - a glass hydrometer with a self-contained mercury thermometer.
