In routine practice of Pharmaceutical Manufacturing Area, the differential pressure maintained is Not Less Than 8 psi. No upper limit is specified. What could be the reason for this Differential Pressure.
I'm not sure where you get the 8psi, your socks would be flying off if it was at that velocity (needed to maintain 8psi). Differential pressures are usually measure in " of H2O, which is 1/27 of a psi. With the large volumes of mass in a room, you are attempting to ensure (based on both static and dynamic conditions) that you maintain that differential. Hence, why alarming is so important as well. Especially in an aseptic environment, where it is critical. You are looking at room air exchanges and maintaining the barrier (sterile for aseptic), not a wind tunnel. Can you please let us know where you got this number?
In my experience I have seen pressure differential requirements of 7.5 - 15.0 Pascals. I agree that 8 psi (~55,000 Pa) is unreasonable and probably not possible.