A specific gravity scale developed by the American Petroleum Institute (API) for measuring the relative density of various petroleum liquids, expressed in degrees. API gravity is gradated in degrees on a hydrometer instrument and was designed so that most values would fall between 10° and 70° API gravity.
What is the relationship between API and specific gravity?
API gravity is thus an inverse measure of a petroleum liquid’s density relative to that of water (also known as specific gravity). It is used to compare densities of petroleum liquids. For example, if one petroleum liquid is less dense than another, it has a greater API gravity.
How is SG calculated from API?
The formula for API gravity is API = (141.5/SG) -131.5 where SG is the specific gravity of the petroleum liquid being measured. For example, for an API gravity of 50, add 131.5 to obtain 181.5. Divide 141.5 by (131.5 + API gravity) to obtain the specific gravity of the oil.
What is API gravity of water?
… petroleum industry, however, uses the American Petroleum Institute (API) gravity scale, in which pure water has been arbitrarily assigned an API gravity of 10°. Liquids lighter than water, such as oil, have API gravities numerically greater than 10.
What is API scale?
the American Petroleum Institute gravity scale: a universally accepted scale of the relative density of fluids that is used in fuel technology and is measured in degrees API. One degree API is equal to (141.5/d)–131.5, where d = relative density at 288.7 K. See also Baumé scale.
Is API gravity linear?
Note that the relationship between °API and specific gravity is not linear. Therefore, the °API gravity of crude blends cannot be calculated by linear averaging of the component °APIs. Specific gravities of the components can be averaged, though, to determine the specific gravity of the resulting blend.
How do you convert gravity to specific gravity?
For example, the specific gravity of 0.84 corresponds to the density of 840 (0.84 x 1000) kg/cubic meters. Multiply the density by the acceleration of gravity (9.81) to calculate the specific weight. In our example, the specific weight is 840 x 9.81 = 8,240.4.
What is the API gravity value of the oil?
between 15 and 45 degrees
API gravity is a commonly used index of the density of a crude oil or refined products. API stands for the American Petroleum Institute, which is the industry organization that created this measure. A crude oil will typically have an API between 15 and 45 degrees. Higher API indicates a lighter (lower density) crude.
What is the viscosity of crude oil?
Crude oils – viscosity and °API
| Crude Oil | Kin. Viscosity [mm²/s] at Temp. | API Gravity °API |
|---|---|---|
| Arabian Light | 10.7 at 20 °C | 34.2 |
| Bonny Light | 2.90 at 50 °C | 35.4 35.8 |
| Boscan | 11233 at 100 °F | 10.1 |
| Brent | 2.86 at 50 °C | 37.9 38.2 |
What does API gravity measure?
A measurement convention established by the American Petroleum Institute for expressing the relative density of petroleum liquids to water; the greater the API gravity, the less dense the material.
How do I convert specific gravity to API?
To convert from specific gravity to API, divide 141.5 by the specific gravity, then subtract 131.5. The specific gravity that should be used is that from oil at sixty degrees Fahrenheit .
How do you calculate API gravity?
To calculate API gravity, you need to know the fluid’s specific gravity. Divide 141.5 by the fluid’s specific gravity and subtract 131.5. If that seems arbitrary, it is because the equation was designed for convenience’s sake.
What is the difference between specific gravity and viscosity?
Like specific gravity, viscosity can be altered by a change in temperature, but unlike specific gravity it can also be altered by agitation. The really important thing to keep in mind is that there is no correlation between viscosity and specific gravity. We measure specific gravity with a hydrometer.
What is viscosity, and why is measuring viscosity important?
Measuring viscosity is an effective way to know the state (properties of matter) or fluidity of a liquid or gas. It plays an important role in the quality control and in various research and development stages of a wide range of industries, including Food, Chemical, Pharmaceutical, Petrochemical , Cosmetics, Paint, Ink, Coatings, Oil and Automotives.
