PDP
Pump Discharge Pressure
Add the pressures needed to deliver the intended stream at the nozzle.
What It Tells You
The pump pressure needed to overcome the whole hose and nozzle package.
Formula
PDP = NP + FL + AL + EP
What the Variables Mean
- PDP
- pump discharge pressure PSI
- NP
- nozzle pressure PSI
- FL
- total hose friction loss PSI
- AL
- appliance loss PSI
- EP
- elevation pressure loss or gain PSI
Plain-Language Explanation
The pump must supply the nozzle pressure and every pressure loss between the pump and the nozzle. Downhill pressure gain is subtracted instead of added.
Worked Example
A line needs 50 PSI NP, 42 PSI FL, and 10 PSI appliance loss.
- PDP = 50 + 42 + 10
Fireground Takeaway
Build PDP from the nozzle back to the pump so each pressure demand is accounted for once.
Practice This Formula
Open Reverse Flow and start a Practice Quiz filtered to this topic.
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