Interconection of risers and others.

[DavidCR]

I have a building with a combined system. With two risers feed by a pump at the basement, the risers rise on independent stair ducts that feed sprinklers and class III hose connections on each floor.
The risers are interconnected on each floor with pressure reducing valves (Wilkins Zurn ZW109FP) this valves isolate the interconnection from the feeders and controls pressure for both sprinklers and hoses.

Question 1.
Is it allowed to interconnect risers at each floor?, NFPA 24 mentions interconnections at the base and top, but I want to clarify if there is something mentioned about interconnections in every floor.

Question 2.
Per NFPA 24 it is required to install checks to prevent circulation. There are no check valves but the Wilkins pressure reducing valves. Do you know if the pressure reducing valves can be considered as check valves to prevent circulation (counter flow on the valve)? Or is it required to install additional checks.

Question 3.
The fire pump (electrical-horizontal) is located under a second basement in a pit, accessed by a square manhole (24"x24") cover on the floor. Then you have to use a fixed ladder to get down to the pump. There is also potable water pumps in this pit. There is a heavy big cover for maintenance purposes to raise equipment with external equipment to be rented. Is it allowed per NFPA 20 to have the pump in a such pit?

 

[cdafd]

question 1 and 2 I would ask why you are looking at nfpa 24 once you are in the building??


3.3 General Definitions.
3.3.1* Private Fire Service Main. Private fire service main, as used in this standard, is that pipe and its appurtenances on private property (1) between a source of water and the base of the system riser for water-based fire protection systems, (2) between a source of water and inlets to foam-making systems, (3) between a source of water and the base elbow of private hydrants or monitor nozzles, and (4) used as fire pump suction and discharge piping, (5) beginning at the inlet side of the check valve on a gravity or pressure tank. [13:3.8]


for number 3 someone approved to be there for what ever reason, and I think a similar question was asked, but I cannot find it.

Would it be allowed today, more than likely not

 

[DavidCR]

Sorry, my mistake, its NFPA 14 not 24, where I found something about interconnection of raisers, does NFPA13 address anything?.

 

[stookeyfpe]

DavidCR,

I have a concern regarding your question 3: Can the fire pump become flooded with water in the pump basin? If so, the existing design does not comply with NFPA 20 in my opinion.

 

[DavidCR]

It does have a pumping system for that, but of course if it fails it´ll be flooded. I really don´t know if a flooding control system could be designed to make a fire pump installation as reliable as it should be.

 

[cdafd]

Question 1

being a sprinkler and standpipe sometimes they are interconected at each floor

Question 2.

now I am not sure of what you are asking on this one????