Sizing of Air exhaust in mini enviroment

[Raedle]

I'm looking for formulas/spreadsheets to assist me with calculating the required opening in an enclosed guard that has HEPA filters on the top. We typically exhaust to the shop floor at a slight positive pressure within the enclosure to keep particles (dirty air) out of the "clean" mini environment.

Is the required opening area equal to the Hepa Filter area?

 

[quark]

You don't require any spreadsheet for this, IMHO, as the calculation is straight forward.

Q = 2610xAxdP^1/2

Where Q is the flowrate in cfm, A is area of the opening in sq.ft and dP is the differential pressure to be maintained in inches of wc. If you know the dP and flowrate exhausted then you can easily calculate the opening area.

However, an opening with adjustable closure(variable area opening) is what you require to settle all the problems.

Regards,