Relative Density

The ratio of a given volume of a substance to that of the same volume of pure water at constant temperature. Relative density decreases with increase of temperature and increases with decrease of temperature. It can only be compared one with another at constant temperature. The standard temperature for quoting the relative density for most petroleum products is 15 Degrees C. Density is also referred to in absolute terms in units of kg/cbm at a particular reference temperature - usually 15 degrees C.