Q = c ??? A √2/a √p1 - p2 Q represents the volumetric flow rate (expressed in gallons per minute, liters per minute, or the like), c is a constant flow aperture parameter, A is the cross-sectional area of the unblocked portion of the unblocked one of the consumer ports 22, 23, p1 is the pressure in inflow conduit 21, and p2 is the pressure in the unblocked one of the consumer conduits