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Fire Sprinkler Discharge Calculator (simplified)

Fluids Flow Design and Engineering

Fire Sprinkler Discharge Calculator (simplified)

This calculator determines the typical discharge vs flow rate of a sprinkler head

Preview: Fire Sprinkler Discharge Calculations

Eq.1
Q = n · [ K · P1/2 ]

Where

Q = flow (gpm)
K = measure of the ease of getting water out of the orifice, related to size and shape of the orifice in units of gpm per (psi)1/2
P = pressure (psi)
n = number of sprinkler heads (identical at same pressure)

Sprinkler K Factors (typical)

Orifice Size
Name
K Factor
1/2"
Standard
5.6
17/32"
Large
8.0
5/8"
Estra Large
11.2

Reference:

NFPA Standard 291, Recommended Practice for Fire Flow Testing and Marking of Hydrants.

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