Leakage through the fixed openings should be restricted as much as possible. The amount of expected leakage can be calculated from the following:
Lv = 4005 x (Rp)1/2
L = 4005 x A x (Rp ) 1/2
Where
• Lv = Leakage velocity in FPM
• L = Air leak age in CFM
• Rp = Room pressure in in-WG
• A = Opening area
Assuming 0.05 in-WG room pressures has an opening of 2 sq-ft opening
Leakage velocity = 0.223 x 4005
= 895 feet per minute
With a total of 2 square feet opening size
Leakage air volume = 2 x 895 = 1800 CFM
