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Orifice Flow Calculations

Circular & Rectangular

Studio Express uses the standard orifice equation for Circular and Rectangular orifices.

Co = 0.60 (or as set in Settings)
Ag = clear opening area in sqft (sqm)
g = 32.16 (9.8) gravity
d = head as measured from the centroid in ft (m)

Orifice equationOrifice Plates

This is a special kind of orifice structure as shown below which contains a series of same-sized holes all within a vertical height.

Orifice Plate

The following formula by McEnroe, 1988 is used to estimate the outflow.

Q = discharge in cfs (cms)
Cp = 0.61
A = cross-sectional area of all the holes, sqft (sqm)
Hs = height in ft (m)
H = distance between water surface and the Invert Elevation in ft (m)