Smooth-Bore Nozzle Flow (GPM)
The flow from a smooth-bore (solid-stream) nozzle.
Example
You enter
- Tip / bore diameter (in) 1.125
- Nozzle pressure (psi) 50
You get
- Flow 266 gpm
- Nozzle reaction 99 lb
Checked against published worked examples from: Fire Engineering (Paul Spurgeon).
Details, formula, and sources
Scopegpm = 29.7 x tip diameter^2 x sqrt(nozzle pressure), with the companion nozzle reaction 1.57 x d^2 x NP. Standard nozzle pressure is 50 psi on a handline and 80 psi on a master stream (both editable). A discharge estimate; incident command and the pump operator govern the actual flow target.
Formula or tablegpm = 29.7 x bore_in^2 x sqrt(nozzle_pressure_psi); companion nozzle reaction = 1.57 x bore_in^2 x nozzle_pressure_psi.
Source and editionIFSTA Pumping Apparatus Driver/Operator Handbook smooth-bore discharge form (by name); classical orifice discharge, no edition cycle.
Free accessThe discharge relation is public physics; standard nozzle pressures are 50 psi handline / 80 psi master. Incident command and the pump operator govern.
What governsEstimate. AHJ and licensed fire protection engineer govern.
API field namesbore_in, nozzle_pressure_psi, gpm, reaction_lb
- Discharge coefficient the 29.7 constant bundles the standard smooth-bore discharge coefficient and unit conversion; the tip must be a true smooth boreIFSTA
- Nozzle pressure default 50 psi handline / 80 psi master, editable to the tip in useIFSTA
- Estimate a discharge estimate; incident command governs the flow target and the pump operator sets engine pressureincident command