OrificeMAC Orifice Discharge Calculator
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OrificeMAC — orifice discharge calculator with head–discharge rating curve

1Orifice & Flow Parameters

Set the discharge coefficient, then pick the unknown to solve for — flow, orifice diameter, or head. US customary units; head is measured to the orifice centroid.

Discharge coeff C
–
Orifice diameter D
in
Head Hto orifice centroid
ft
Flow Qdischarge
cfs

2Result

Discharge — Q —
Jet velocity — V
—ft/s
Head : diameter — H/D
—
Head to invert — Hinv
—ft
Calculation audit
Q = C·A·√(2gH)  |  H = (Q / (C·A))² / (2g)  |  A = πD²/4  |  V = Q/A  (g = 32.2 ft/s²)

3Orifice Elevation

side section · head H to centroid · jet to atmosphere · H & D scaled independently

4Head–Discharge Rating Curve

head H (y) vs discharge Q (x) at the current C and D · marker = operating point