Specific Gravity

The Specific gravity (S.G.) is a measure of the relative density of a substance as compared to the density of water at standard temperature. The Physicists use 39.2°F (4°C) as the standard, though engineers normally use 60°F. In the International System of Units (i.e., SI Units), the density of water is 1.00 g/cm³ at standard temperature. And hence, the specific gravity (that is dimensionless) for a liquid has similar numerical value as its density in units is g/cm³. As the density of a fluid differs with temperature, specific gravities should be determined and identified at specific temperatures.