Pressure Reducing Valves

[fayazdin1]

I am designing wet riser system with landing valve and 25-mm hose reel for a 4-story building. The building is a part of a campus with a fire ring main maintained at 10-bar (150-psi). The owner asked me to provide landing valve with PRV & should have PRV at hose reels. The system is to be designed based on British Standards.

Question: In my opinion, the system does not require PRVs because the ring main pressure which is fitted with a fire pump is 150-psi

NFPA standard calls for PRV if the system pressure exceeds 175-psi. I don’t know British Standard.
Any reference to British Standard for maximum pressure will be appreciated
Please help

 

[Sdpaddler50]

Can't help you with British standard, but 150 psi should not need prv's as you note. Prv's should be avoided whenever possible in fire systems. In no flow conditions these are in the closed position which can inherently lead to problems when the open up to flow in a fire. Reason, most owners don't test or maintain these, as only prv's,s on hose, not sprinklers, are required to be fully function tested per napa 25.

 

[cdafd]

is it ever possible for the pressure to go over 150??

as in a fire department connection, that a fire truck would add pressure over 150 or 175??

or some other scenario????