Existing building with a vertical in-line fire pump that has not been tested in the last 5-6 years. The fire pump is fed from a water storage tank where the top of the tank is roughly 12-15 feet above the fire pump.
The fire pump is rated 55 psi at 500 gpm. There is about 60 feet of 4-inch main that connects the discharge side of the fire pump to the fire pump test header. This stretch of main also includes at least 6 elbows and a tee. The test header has two 2-1/2" connections.
With a hose monster and 15-feet of hose connected to the pump test header, we are only able to flow about 400 gpm out of the test header. At this flow rate, the suction side fire pump gauge reads -20 psi and the discharge reads 25 psi.
In short we are not getting the 100% flow (of 500 gpm) or the rated pressure (of 55 psi).
I can see some flow being restricted due to the long run from the pump room to the building exterior, but are there other issues I'm not thinking about here that would cause this? Obstruction in the main perhaps? Any tips on actually getting the flow up to 100%? Thanks.
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