ASTM D1657 Test Method for Density or Relative Density of Light Hydrocarbons by Pressure Hydrometer
4. Summary of Test Method
4.1 The apparatus is purged with a portion of the sample before filling with the portion to be used for testing. The pressure cylinder is filled to a level at which the enclosed hydrometer floats freely, and the cylinder is then placed in a constant-temperature bath (if needed). When the temperature has reached equilibrium, the hydrometer reading and the temperature of the sample are read. The observed hydrometer reading is corrected for the meniscus effect, alternate calibration temperature effects and reduced to the reference temperature by means of the volume correction factors or tables as applicable by use of the appropriate 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, and observed temperature from the thermometer.
5. Significance and Use
5.1 The density or relative density of light hydrocarbons and liquefied petroleum gases is used in custody transfer quantity calculations or to satisfy transportation, storage, and regulatory requirements.
