Pump on basement

[DavidCR]

Hi to everybody there, I have 2 questions, that I´d´appreciate a lot your comments about. First I describe the case.

Case: Hydroelectric power house. Remote site.
One main floor at the surface. 5 underground levels.
We plan to build a tank (embebed) at the bottom of the building, to install a NFPA 20 vertical fire pump down there on the lowest floor.

We have to feed a NFPA 14 hose system (hose conections for each floor) inside of the power house building, and NFPA 24 hydrant yard mains at the surface level for the exterior of the power house and other buildings (warehouses, workshop, etc.)

1. ¿Is it OK to install the fire pump inside and at the bottom of the power house building?.

(We want to do this because if we install the pump at the surface level, we would have to install a NFPA 22 tank and an aditional pumping system to fill it. If we install the pump at the bottom we would save money on the filling system and the tank. We don´t have an alternative source of water other than the water we can get from the bottom level (or at least cheap sources)).

2. ¿Is it OK to connect each hose station (of the underground floors) directly from the pipe that goes up to feed the yard mains?. Or it is necesary to go up to the surface and then down again with a standpipe that goes down to feed the hose conections?

Any comment will be highly appreciated.

 

[TravisMack]

I am not sure if I fully understand your layout, but I will give it a shot:

As far as I know, it is permisible to install pumps on subgrade floors. However, you need to be able to get it down there and back up again should the need arise for maintenance. You will also need adequate ventilation for the equipment.

"We want to do this because if we install the pump at the surface level, we would have to install a NFPA 22 tank and an aditional pumping system to fill it"

This is not necessarily the case. You can build a well and use that as the water source if possible for the area you are in. The well simply needs to be able to supply the same volume of water as you would have in a stored tank. Check NFPA 20 for the well requirements if you want to go down that road. If there are sprinklers, you need to make sure you account for the raw water source provisions.

"Is it OK to connect each hose station (of the underground floors) directly from the pipe that goes up to feed the yard mains?. Or it is necesary to go up to the surface and then down again with a standpipe that goes down to feed the hose conections?"

I would run a separate standpipe for the hose valves. This will allow you to work on the standpipe or the yard system independently without shutting down all of the fire protection available. You don't have to go up and back down, simply have 2 vertical pipes going up from the pump. 1 will have hose valves, the other will be an express main for the yard system feed.

When using the pump to feed the yard mains, be sure that you have an adequate supply to meet the site fire flow requirements which will likely be greater in volume than the sprinkler/standpipe requirements.

Feel free to post if you have any further questions.

 

[stookeyfpe]

Your design for item 1 meets NFPA 20. NFPA 20 has no specific limitations by occupancy as to where the pump is installed.

Concerning the use of the standpipe feeding the yard mains, I found nothing in NFPA 24 that prohibits this. However, NFPA 14 does limit the discharge pressure at hose 1 1/2" valves on Class I-III standpipes. NFPA 14, section 7.2.1.1 requires a pressure regulating device to limit the discharge pressure to 100 PSIG at the flow rate specified in section 7.10. I don't know what your hydraulic demand is for your yard mains so you will want to check this.

 

[DavidCR]

Thanks a lot to you both.

Also..
On 1, we are aware that having the pump down there is a little risky, we need extra precautions against a flooding accident. In general, as possible, one has to avoid to install equipment on the last floor of a hydroelectric power house.
On 2, we are considering the use of pressure reducing valves, and I am on the side for an independent branch for the hose connections, but I think that I need more "back-up" on this.
Your comments gave me a better view of the situation.