One Deluge Valve for Two Generator Rooms?

8/4/2023

We have a project where a foam-water system is installed for two generator rooms. The rooms are on the same floor and some distance from each other, which is also on the same floor as the fire pump, which is served by a vertical foam bladder tank.

I've read here before that it's possible to have one proportioner serving both of them, but is it possible to have one deluge valve to serve both rooms?

If so, do I need to add motorized butterfly valves to regulate the flow direction?

Really appreciate the input.

Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe

10 Comments

Dan Wilder

8/4/2023 08:00:32 am

No issue with serving multiple areas from the same valve, proportioner, or system overall as long as the owner understands that if one system goes off...both rooms are getting a bubble bath. Typically, that is motive enough to have separate valves controlling each room.

If the design does utilize one valve for both rooms, make sure that the design incorporates both systems flowing simultaneously for sizing of pipes and foam regardless of any possible isolation valve installation.

As for the additional motorized valve to control flow....it's a bad idea IMO. Motorized (electric or hydraulic) butterfly valves do not have a "Fail Open" feature, they would need a battery backup to open a valve in case of an issue and I would highly suggest having a manual override ability. They also have additional relays and voltage requirements for operation & monitoring (24VDC or 120-125 VAC). All "extra" things that require additional inspections & maintenance.

We were recently asked about providing a remote operated control valve to allow a facility operator to remote close the supply to several transformer deluge systems because the facility is not manned 24/7, but it is remote monitored 24/7. As this entity is acting as their own AHJ, the valve chosen is not UL/FM for fire protection (we could not find one anyway) and they approved it. The backside fire alarm and BMS integration has been an adventure.

Anthony

8/4/2023 08:08:45 am

Dan should get extra points for "bubble bath."

Also I agree the cost in annoyance with the motorized butterfly valve is better spent on a second deluge valve.

Jesse

8/4/2023 08:09:07 am

The installation as you described it is code-compliant, and I've seen it before, but isn't really advisable. If the generator rooms are critical to operations, you could have a prolonged interruption if one system trips because both rooms will be filled.

Glenn Berger

8/4/2023 08:19:07 am

1) Are you planning for pre-action foam systems or deluge foam systems? If deluge then the double bubble bath scenario is appropriate.

2) Need to ensure that any type of motorized valve (or any valve for that point) is approved for use in a fire suppression system.

3) I would not recommend using one system to protect two isolated (and possibly fire-rated) rooms, especially mission-critical rooms. Cheaper designs are necessary the correct designs.

Casey Milhorn

8/4/2023 08:19:56 am

I agree with everyone as well. Definitely a no on the solenoid control valves, bad idea. I don't know the size of each room, but flowing both at once in a calculation is bound to lead to a larger valve, bulk feed main, possibly some balancing hoops to jump through if they aren't equal size and equal distances from the deluge valve. I think I would have to choose what I would imagine are two smaller deluge valves over one large deluge valve. If the deluge valves end up in the pump room, or adjacent to each other in a shared closet, I believe you can share one releasing panel if you are going with a modern deluge setup using heat detectors or similar triggers.

David Kendrick

8/4/2023 09:52:08 am

Question: Is the system open head or closed head?

I'm aware you referred to a deluge valve. Are these really unsupervised pre action systems?

Several recommended two separate deluge valves instead of a division valve. Personnally, I would agree.

It would be noted with two separate areas the system design calculations will likely result in smaller pipe and deluge valves. You will still have two detection systems, one for each area.

There are economic incentives to have two separate deluge valves.

This is a lobbying effort for two separate systems.

Mark Harris

8/4/2023 11:27:16 am

Adding to the detection comments if you did this as one zone with the rooms far apart owner and first responders will not know which room caused the system to trip. With an intelligent detection system that could be mapped so each room gave notification and tripped the single deluge valve solenoid but I agree with the other comments that two deluge valves make more sense.

Douglas link

8/5/2023 04:13:27 am

I’m not looking at the rules here; “I’m looking at the overall practicality of the building-wide fire protection. These are questions that I would ask when trying to figure out whether the foam-water systems for the two rooms should be totally separated, or somehow combined.

Question: Why are there two separated generator rooms? I don’t know how the building is wired, but is it so that if one generator fails, the other will still operate when there’s a neighborhood power blackout?

Question: Are the generators themselves protected from the foam-water deluge so they can continue operating even when the room each one is in has been deluged?

Question: Have the proposed motorized butterfly valves, that are supposed to regulate flow direction, been tested to work under these conditions, and listed for use, by a nationally known testing laboratory like UL, FM, CE, etc.,? If not, is there a guarantee that one of the valves won’t leak when only one room is on fire?

Question: When there is a neighborhood-wide power failure at the same time both generators fail, Is the fire pump an electric fire pump that can also fail, or is the fire pump a diesel fire pump that can still operate even when there is a total power loss?

When making these kinds of decisions, even if the rules and codes don’t cover this exact scenario, the whole building-wide fire protection system still needs to be considered.

Pete D.

8/13/2023 08:06:24 am

I've designed 2 control areas on 1 system valve before. Whatever the foam system area ends up being, you need to do the demand calc to prove the water density delivery. Then you need to do a source calc to size the bladder tank and buy the foam concentrate. In a real flowing scenario, supply pressure - friction loss - pressure at the flowing orifices = zero. It's not as if the sprinkler system achieves the design pressure and then throttles itself. Many folks forget this and undersized their tank or don't buy enough foam.

Tahasin Khan Mohammed

11/12/2023 01:46:24 am

foam bladder tank location in generator room it's allowed or not as per NFPA

One Deluge Valve for Two Generator Rooms?

Leave a Reply.

ALL-ACCESS

SUBSCRIBE

COMMUNITY

YOUR POST

PE EXAM

FILTERS

ARCHIVES

PE PREP SERIES