Fire main testing

Would like to determine if a fire pump’s ouput is in compliance with 46 cfr 142.325, but only have a pressure gauge at the pump. No pitot-tube gauge. No good way to measure flow rate.
The cfr reads:
“a pitot-tube pressure of at least 344 kilopascals (kPa) (50 pounds per square inch (psi)), and a flow rate of at least 300 liters per minute (lpm) (80 gallons per minute (gpm))”

Any ideas? Any and all information much appreciated.

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Old school style would be a couple of empty 40 gallon drums and simply time how long it took to fill them at max pressure.
Interestingly enough, 300 litres (note the correct spelling!) is 79 US gallons and 66 UK gallons so better check where you are before demonstrating in front of a surveyor.
I thought that they used pitot tubes for air speed indication?


If you have 125 psi at the gauge your good

I’ve only ever thought of them relative to airspeed but by design can measure pressure flow differentials in liquids as well as gases.