The door fan merely measures the size of the holes in the enclosure and the pressure that may exist across them. The computer on board does the rest of the simulation and comes up with the prediction.
Retrotec began producing state of the art air flow testing equipment in 1981 and has performed thousands of tests, making them a leader in the industry. Retrotec gave presentations to the FSSA, NFPA, SFPE, and NAFED, and wrote most of NFPA Appendix B.
Global Fire Suppression recommends doing a room integrity test anytime holes are made in the protected enclosure. It is also recommended that room integrity be done before and after any new fire suppression equipment is installed. This affords the opportunity to properly seal the room before extra equipment is moved in.
Door fan replaces the discharge test.
Now both NFPA2001 and 12A require an enclosure test (section 4-7.2.3) as part of the acceptance procedure for all clean agent systems.