To: Cry22
Please allow me to shed more light about the sketch.
As you have stated, there are indeed two corridors in parallel in each of the wards but both end up in the main corridor and not in any independent staircase of their own.
The zone valves for each ward are provided to isolate the ward from the rest of the network for maintenance and the check valve would prevent draining the pipes of the zone should the main pipe running in the corridor be drained for maintenance purposes.
However, the flow detection switch in each zone appears to be redundant because any flow will also trip the flow switch of the main riser. If there was BMS system with addressable flow switches, it would circumvent this problem, but there isn’t any.
For example, if any zone flow switch is activated it will also activate the flow switch of the main riser.
Furthermore, it seems risky to tap off the FHC from the same branches that supply the sprinklers. But on the other hand, since the reel is only 1 inch (Class 2 installation) with 50 GPM flow, that is equivalent to the discharge of 4 sprinklers, I would like to understand the technical reason why this might not be allowed.
Ordinarily, only 8 sprinklers are allowed on either side of the branch, but with the hose reel, it will exceed that. Given that the pump capacity can meet the flow requirements, it might be OK.
PLEASE rest assured that the system will still be inspected by the fire department and is subject to approval or disapproval.
The intent of floating this question is for educational purposes, because I was unable to find my answers from the various sections of NFPA.
Please shed any more light about this situation at your convenience.
Thanks in Advance.