Water Supply Tool

Hydrant Flow Calculator

Estimate fire hydrant available GPM from static, residual, target residual, measured flow, or pitot pressure for training and preplanning.

Inputs

Static pressure (PSI)

Residual pressure (PSI)

Measured flow during test (GPM)

Target residual pressure (PSI)

Add pitot/outlet calculation?

Outlet diameter (in)

Pitot pressure (PSI)

Discharge coefficient

Training/reference aid only. Follow department SOPs, instructor direction, manufacturer data, and local conditions.

Results

Available flow at target residual

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Pressure drop used

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Pitot/outlet flow

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Hydrant status

—

Enter values and calculate.

How the hydrant flow estimate works

Enter static pressure, residual pressure, and the measured flow from a hydrant test. FireOps Calc projects available GPM at your selected target residual pressure using the values entered above. If you only have outlet diameter and pitot pressure, turn on the pitot option to estimate the flowing outlet GPM first.

Available GPM formula used by this tool: Flow × ((Static − Target Residual) ÷ (Static − Residual))^0.54.

Hydrant testingAvailable GPMStatic / residual pressureWater supply planning

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