Mass Flow Rate :

According to the S.A. Moss equation, the mass flow rate through an orifice is given as :

W(lb/s) = 0.5303 x A (in2) x C x P (psia) /

where C = 0.97 for a smooth edged hole and C = 0.61 for a sharp edged orifice.

The equation can be modified to show air leakage in standard cubic feet per minute at : T = 70 F = 530 R and [R] = [C] 9/5 + 491.67 the density of air at 70 F is 0.7494 lb/ft3 such that:

V (scfm) = 0.5303 x / 4 x [D (in)]2 x 0.61 x P (psia) / [x 0.07494 lb/ft3] x 60 s/min

V (scfm) = 8.8356 x [D (in)]2 x P (psia) [ Volume Flow Rate ]