Save, load, and manage operational hose/nozzle setups.
Select a hydraulic calculation mode.
Reverse Flow Mode: Enter PDP to estimate GPM and Nozzle Pressure based on hose and nozzle characteristics.
Build the supply-side hydraulic path feeding the attack lines.
Dual supply assumes two matching supply lines feeding a Siamese connection.
Pump to first appliance.
Second hose section between appliances.
Configure nozzle paths and attack line hydraulics.
Optional single supply section before the attack line.
Configure the supply hose feeding the attack section.
Only nozzle style, nozzle pressure, and hose coefficient matter for these calculations.
Used for scenario clarity and displayed in the result. In Reverse Flow mode, nozzle pressure defaults to the highest mathematically reachable value.
Default is 25 psi. Change only if your device has been flow tested.
Manual PSI value. Use negative values for elevation gain/downhill pumping.
Splits total flow evenly across two identical supply lines for friction loss calculation.
Split Lay PDP
— PSISupply Layout
—Total Supply Flow
—Supply Friction Loss
—Appliance Loss
—Section Flow
—Supply 2 FL
—Appliance 2 Loss
—Delivered Flow
—Nozzle Pressure
—Attack Line FL
—Nozzle Reaction
—Delivered Flow
—Nozzle Pressure
—Attack Line FL
—Nozzle Reaction
—Rounded Flow
Calculated
—Total FL
—FL / 100'
—Nozzle
—Reaction
—Setup
—Reverse Flow Formula
Total friction loss = PDP − nozzle pressure − appliance/elevation loss.
Friction loss per 100' = total friction loss ÷ hose length in hundreds of feet.
GPM = √(FL per 100' ÷ coefficient) × 100.
Final result rounds to the nearest 5 GPM.
Required PDP Formula
Required PDP = nozzle pressure + friction loss + appliance/elevation loss.
Relay Pumping Formula
Relay PDP = relay friction loss + receiving engine residual + appliance/elevation loss.
Split Lay Formula
Total PDP = supply friction loss + appliance loss + highest attack-side pressure demand.
For unequal attack lines, the higher-demand line drives PDP. Lower-demand lines are recalculated to show actual delivered nozzle pressure, flow, friction loss, and nozzle reaction.
Fog nozzle actual flow = target flow × √(actual nozzle pressure ÷ target nozzle pressure).
Smoothbore flow = 29.7 × tip diameter² × √nozzle pressure.
Default Coefficients
1" = 100, 1.5" = 24, 1.75” = 15.5, 1.88” = 8, 2” = 4, 2.25” = 3, 2.5” = 2, 3” = 0.8, Dual 3” = 0.2, 4” = 0.2, 5” = 0.08
About / How to Use
Reverse Flow Mode estimates GPM by working backwards from pump discharge pressure, nozzle pressure, hose length, hose coefficient, and appliance/elevation loss.
Required PDP Mode calculates the pump discharge pressure needed to achieve a target flow.
Relay Pumping Mode calculates the required discharge pressure for a relay pumper to supply a receiving engine with a target flow and residual pressure.
Split Lay Mode models split-supply and split-attack hose layouts with dynamic pressure balancing, recalculated nozzle pressures, delivered flow, and appliance loss handling.
When unequal attack lines are supplied from a common source, lower-demand lines may become overpressured. Reverse Flow dynamically recalculates nozzle pressure, flow, friction loss, and nozzle reaction to better reflect real-world hydraulic behavior.
Smoothbore tip size is selected manually. In Reverse Flow and Split Lay modes, nozzle pressure and delivered flow may be dynamically recalculated based on available pressure, hose configuration, and hydraulic demand.
Actual pump discharge pressure may vary due to internal plumbing, apparatus piping, valves, appliances, intake restrictions, and other system-specific factors not automatically accounted for by the calculators.
This application is intended for training, reference, and operational decision support. Always follow local pump charts, equipment testing, department policy, and instructor guidance.