We will now use DIERS methology to perform a two-phase test to determine if two-phase flow is likely for our single-phase Fire case. The two-phase test is based on an article by Harold Fisher , An Overview of Emergency Relief System Design Practice". Union Carbide Chemicals and Plastices Company, Inc.
To perform the two-phase test the user can transfer his single-phase vapor/gas flow rate. And transfer the vessel cross-sectional area, and vapor volume fraction from the the two-phase "Vessel Volume Calculator" tab results below.