Fire Pumps and Overpressure
Fire Pumps and Overpressure
(OP)
We have building with several double interlock preaction systems all served by one common riser. This system is boosted by an electric fire pump complete with a pressure relief valve set at 170 psi.
The problem we are having is to do with system overpressure at pump start up. When the pump starts it provides a "bump" on the system raising the system pressure above the check valve to approx. 245 psi. Conversations with relif valve manufacturers indicate that these valves do take a second or two to open.
My question is: How can we contain the initial bump without modifying the pump. My initial thoughts are some type of retard chamber, however I am not familiar with these with such a pressure bump. Any ideas?
The problem we are having is to do with system overpressure at pump start up. When the pump starts it provides a "bump" on the system raising the system pressure above the check valve to approx. 245 psi. Conversations with relif valve manufacturers indicate that these valves do take a second or two to open.
My question is: How can we contain the initial bump without modifying the pump. My initial thoughts are some type of retard chamber, however I am not familiar with these with such a pressure bump. Any ideas?





RE: Fire Pumps and Overpressure
There are surge suppressers available for this type of application. I don't know of a mfg off hand, but I do have a picture of one and will be glad to send it to you. Let me know.
RE: Fire Pumps and Overpressure
RE: Fire Pumps and Overpressure
J. Scott Mitchell
Fire Protection Engineer
RE: Fire Pumps and Overpressure
And thanks again.
RE: Fire Pumps and Overpressure
I agree with Scott, the original designer screwed up big time. I recently worked on a project very similar. The only solution other than replacing the pump that I know of is to add a pressure-reducing valve. I personally think it is a poor solution but have seen other people use them. Then in addition to the pressure-reducing valve they installed a couple surge tanks.
Good Luck.
RE: Fire Pumps and Overpressure
Bryce
SPK Engineering
http://www.spk.fr/index.htm?referrer=securite_incendie
RE: Fire Pumps and Overpressure
Is this a combined sprinkler and standpipe system? If so how about pressure reducing valves at sprinkler system connections?
RE: Fire Pumps and Overpressure
I heard they sometimes solve this problem wit a jaw-way valve (don't know if I spell it correctly) . This is a valve with a quick response time, to relief the pressure in the system.
This bump could also be the result of water hammering. Check literature how to prevent this from hapening.
bye
RE: Fire Pumps and Overpressure