API — American Petroleum Institute liquid density

The API liquid density correlation is used to predict liquid densities, published in 19841. An initial density is calculated at 60°F using the weight average of the components. The reduced temperature and pressure of the stream at 60°F and 14.7 psia are computed by using Kay's rule; for example, the reduced temperature and pressure are assumed to be a linear function of the liquid mole fraction. A density factor, C, is then read from Figure 6A2.22 in the API Technical Data Book. A second correction factor is then determined corresponding to the reduced temperature and pressure at the actual fluid conditions.