API Gravity also known as The American Petroleum Institute Gravity, is the measure of the density of a petroleum liquid in relation to the density of water. If the gravity is less than 10, the petroleum liquid is heavier and thus it sinks and if the gravity is greater than 10, the liquid is lighter, so it floats on water. It is an inverse measure of the density of the petroleum liquid related to that of water. This means that the lighter the petroleum liquid the higher the API gravity and vice-versa. Less dense liquids or the light petroleum liquids are preferable to more dense liquids because they contain greater quantities of hydrocarbons which can be converted into gasoline.
Costa Oil explains API Gravity
The American Petroleum Institute is a main United States trade association for natural gas and oil industry. More than 400 corporations in the petroleum industry are represented by the API which helps to set standards for the production, refinement and distribution of petroleum products. The most important standard set by API is the method which can be used for measuring or calculating the density of the petroleum liquids. The standard is known as API Gravity. It is the ratio of the density of petroleum liquids to that of water with the help of calculation, designed to ensure the consistent results in measurement.
Generally, oil or other petroleum liquids with API gravity between 40 to 45 dominate with highest prices and above 45 their molecular chains become shorter and thus less valuable for refineries. Petroleum liquids with less than 10 API gravity are referred as bitumen or extra heavy oil.