Smooth-Bore Tip Diameter for a Target Flow

d = sqrt( gpm / (29.7 x sqrt(NP)) ). 250 gpm at 50 psi wants a 1.09 in tip (round up to a stocked 1-1/8 in), which handles about 93 lb of reaction. Answers 'what tip for this flow' instead of the flow from a set tip. Round to a stocked size; incident command and the pump operator govern.

bore_in = sqrt( target_gpm / (29.7 x sqrt(nozzle_pressure_psi)) ), the inverse of gpm = 29.7 x bore_in^2 x sqrt(NP); companion nozzle reaction = 1.57 x bore_in^2 x NP.

IFSTA Pumping Apparatus Driver/Operator Handbook smooth-bore discharge form (by name), solved for the diameter; classical orifice discharge, no edition cycle.

The discharge relation is public physics; standard nozzle pressures are 50 psi handline / 80 psi master. Incident command and the pump operator govern.

Estimate. AHJ and licensed fire protection engineer govern.

Field names used by the API: target_gpm, nozzle_pressure_psi, bore_in, 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