Dynamic AirFlow Troubles! Plz help

[rwbanks]

I am a Clean Room Specialists and am having some issues with a dynamic system which is being controlled by Price vav's at which are attempting to maintain a negative pressure and constant flow in a space. I have noticed at times that the DP varies although flows are being maintained and duct static pressures are maintained.

The system varies from -.06(ideal) to -.09(life safety concern) however like I said the flow rates have negligible change no more than about 35cfm on a system that flowing 1200cfm. When the system pressure gets upwards of -.09 we have door closing issues. Any suggestions or information would be helpful.

Thanks

BB

[beenthere]

-.09(life safety concern)???

There is more of pressure loss going from 0' elevation to 500' elevation.

[rwbanks]

Its been determined that once the space starts to hit a -.1 it takes upwards of 60lbs of pull to open the door. In case of an emergency its a concern on whether a 4'10" 90lbs young lady can open the door or not.

[beenthere]

A 3'X7' door with a negative pressure of .1" holding it shut, would only have a total of 10.8 pounds of force against it.

[Pete838]

*