What is American Petroleum Institute scale on hydrometers?

Answer:

The American Petroleum Institute (API) scale on hydrometers is an arbitrary scale based on Relative Density (Specific Gravity) where -

API = (141.5 divided by the Relative Density at 60oF) - 131.5

First answer by Stevenson Reeves Ltd. Last edit by Stevenson Reeves Ltd. Contributor trust: 3 [recommend contributor recommended]. Question popularity: 3 [recommend question].