I have question regarding fire pump capacity.
In my situation the water department is requiring a city tap size to be 2 pipe sizes larger than the fire protection backflow preventer.
In my project, I was using a 4" backflow and 400 gpm fire pump so my underground/city tap would be required to be at least 6 inches.
The AHJ is requiring me to increase the area size in one of my remote areas. So, my sprinkler demand now becomes 582 gpm. To avoid having to use a 500gpm fire pump (with a minimum suction size of 6-inch) and increase the underground to 8-inch, could I still use the 400 gpm fire pump to supply the 582 gpm demand?
This comes out to about 145% of the pumps rated capacity.
I have never come close to the 150% mark before and just want to see what others think. If the underground size wasn't required to be 2 inches larger I wouldn't even think about it and go with the 500 gpm pump.
Thanks in advance.
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