Pump Discharge Pressure Calculator

Pump discharge pressure (PDP) is the total pressure your pump operator needs to set so the nozzle gets the pressure it needs to produce an effective fire stream. Set it too low and your crew gets a weak stream. Set it too high and you risk blown hose or an injured nozzle operator.

PDP accounts for everything that eats pressure between the pump and the nozzle: friction inside the hose, the weight of water going uphill (or the assist going downhill), and any appliances in the line that create additional friction loss.

The standard formula used across the fire service is:

Every appliance between the pump and the nozzle creates additional friction loss. Standpipe connections and aerial devices typically add 25 PSI. Wyes and siamese connections add about 10 PSI each. An inline foam eductor can add 200 PSI.

Always account for every appliance in your hose lay. Missing one can mean the difference between an effective fire stream and a crew wondering why they're not getting water.