### Pitot Gauges: How Do I Calculate the PSI to GPM …

Step 5: Multiply the final two nuers to solve for Q, the discharge in GPM. 174.6 x 7.8740 = 1,375 GPM Now that you’ve got a grasp on how PSI, discharge coefficients, and diameter impact a hydrant’s flow rates, try our handy GPM calculator for fire hydrants:

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