**DENSITY**

DENSITY [kg/m3, kmol/m3, lbm/ft3, lbmol/ft3] returns the density (inverse specific volume) of a specified substance. The value and units of the returned value depends on the Unit System setting. Density is only a function of temperature for incompressible substances. Two arguments are required for all pure real fluids and ideal gases; three are needed for moist air (AIRH2O).

Note that, for substance AirH2O (psychrometrics), the density returned by this function is not equal to the inverse of specific volume. Following the ASHRAE Handbook of Fundamentals Chapter 1, 2009, density is defined as the total (air + water vapor) mass divided by the total volume.

The list of property identifiers needed in the calling arguments and instructions are available in the Thermophysical Function help.