Discharge head for fire pump relief valves
Discharge head for fire pump relief valves
(OP)
An 8 "diameter discharge head was installed in which the outputs of the pressure relief valves of 5 fire pumps were connected.
One of them is 1000 gpm capacity and the others are 2500 gpm.
Is this arrangement acceptable?
One of them is 1000 gpm capacity and the others are 2500 gpm.
Is this arrangement acceptable?





RE: Discharge head for fire pump relief valves
The pipe should be 10" for a 2500 gpm pumps. They would need to change the 8" to a 10" for the 2500 gpm pumps to meet NFPA.
RE: Discharge head for fire pump relief valves
RE: Discharge head for fire pump relief valves
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: Discharge head for fire pump relief valves
Three are powered with electric motor and 2 with diesel engine.
I consider that the diameter of the head is very small to operate with that arrangement and that they should discharge individually.
A schematic drawing of the arrangement is attached.
RE: Discharge head for fire pump relief valves
RE: Discharge head for fire pump relief valves
RE: Discharge head for fire pump relief valves
Therefore, the 5 pumps can operate simultaneously.
RE: Discharge head for fire pump relief valves
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: Discharge head for fire pump relief valves
RE: Discharge head for fire pump relief valves
It is a very special case but it was proven that this is likely to happen.
RE: Discharge head for fire pump relief valves
RE: Discharge head for fire pump relief valves
Certainly not on a fire water system where they treat pumps as disposable items and in many case regularly "test" the pumps for long periods against dead head with no flow.
Hence first off find out what these relief valves do, why they are fitted, what they are trying to protect, size / flow rate etc.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Discharge head for fire pump relief valves
So how old is this set up??
Is it in the USS
Do you have a fire sprinkler company you can talk to? I take it you do not work for a fire sprinkler company??
RE: Discharge head for fire pump relief valves
4.18.1.2 Where a diesel engine fire pump is installed and where a total of 121 percent of the net rated shutoff (churn) pressure plus the maximum static suction pressure, adjusted for elevation, exceeds the pressure for which the system components are rated, a pressure relief valve shall be installed.
It goes on to say the following...
Prior to the 1996 edition, NFPA 20 required the installation of pressure relief valves for all diesel engine fire pumps. This requirement was based on the assumption that, if engines ran too fast (a condition known as overspeed), the fire protection system would be exposed to pressures in excess of the pressure ratings of the system components. Because an overspeed shutdown device is required, the technical committee believes that a pressure relief valve is not needed on all diesel fire pump installations. Pumps that create pressures less than the pressure rating of the fire protection system components [typically 175 psi (912.1 bar)] at 110 percent of rated speed do not need a pressure relief valve.
RE: Discharge head for fire pump relief valves
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.