Maximum Differential Pressure across Clean Rooms

[COLOR="#0000CD"]Our facility has been designed to achieve minimum differential pressure across clean rooms. The lower limits of differential pressure between different rooms have been set at 10Pa, 20Pa or 40Pa.

However, we have been requested to also define upper specification limits for the differential pressure across the rooms. Their concern was that the higher the differential pressure, the more turbulent the air flow in the room is. Turbulence is required in Class B, C & D areas, however up to a certain extent in order to avoid contamination from the floor etc.

Is there any rule or guidance to be followed in order to define the upper specification limits? Which would be the rational for defining these limits? [/color]

I am not aware about rule or guidance defining upper delta p limits. I think the best is to find the upper limits with help of a smoke (by smoke studies, air flow visualization) at higher diff.pressures between rooms. Do not forget to take video for evidence.

dear a.danihlik,
i first time heard about smoke studies for Class B,C &D. is it really required? as class B,C,D are having nonlaminar flow pattern.
normal practice is to keep 10 pa across same class and 15 pa for different class adjacent room. idea is to avoid cross contamination.

Dear Ravi Asalkar,
I was not telling about necessity of smoke studies in class B,C,D as they are normally done in A class.
My meaning is to use a smoke to see air flow behavior at higher delta p to define upper limits as Mantonopoulou has been requested.

There is no rational for the upper limit. You have to set the normal operational range, action and alert limits.

When you set these limits, you have to avoid high values of DP between two rooms, which could lead to problems like: difficulty in opening/closing doors, bulding fabric failures, etc.