The reference used for the computations performed by this module is:

Steam Flow through Safety Valve Vent Pipes, by H. E. Brandmailer and M. E. Knebel, published in 1975 by ASME - ASME paper n 75-WA/FE-23.

The equations are not limited to "steam".

Acquire and read the paper, then draw your own conclusions as to limitations. In our (COADE) seminars, I always state that this module is based on only a single paper (source). If you have a better source for the thrust load, use it. This module should only be used as a last resort.