ISO 3675
DENSITY, RELATIVE DENSITY, OR API GRAVITY OF CRUDE PETROLEUM AND LIQUID PETROLEUM PRODUCTS BY HYDROMETER METHOD.
This International Standard specifies a method for the laboratory determination, using a glass hydrometer, of the density at 15°C of crude petroleum, liquid petroleum products, and mixtures of petroleum and non-petroleum products normally handled as liquids and having a Reid vapour pressure (RVP) of 100 kPa or less.