The American Petroleum Institute gravity, or API gravity, is a measure of how heavy or light a petroleum liquid is compared to water. If its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks. API gravity is thus an inverse measure of the relative density of a petroleum liquid and the density of water, but it is used to compare the relative densities of petroleum liquids. For example, if one petroleum liquid floats on another and is therefore less dense, it has a greater API gravity. Although mathematically, API gravity has no units (see the formula below), it is nevertheless referred to as being in "degrees". API gravity is gradated in degrees on a hydrometer instrument. The API scale was designed so that most values would fall between 10 and 70 API gravity degrees.
Read more about API Gravity: History of Development, API Gravity Formulas, Using API Gravity To Calculate Barrels of Crude Oil Per Metric Ton, Measurement of API Gravity From Its Density, Direct Measurement of API Gravity (Hydrometer Method), Classifications or Grades
Famous quotes containing the word gravity:
“Here I sit down to form characters. One I intend to be all goodness; All goodness he is. Another I intend to be all gravity; All gravity he is. Another Lady Gish; All Lady Gish she is. I am all the while absorbed in the character. It is not fair to say—I, identically I, am anywhere, while I keep within the character.”
—Samuel Richardson (1689–1761)