Deluge and Wet Sprinkler System in Same Area?

8/14/2024

Can you have two fire sprinkler systems in one area?

A place is looking to charge a fleet of electric vans in an enclosed parking structure. The building already has a wet system designed for Ordinary Hazard Group 2. They want to put in a 16-zone extra-hazard (group 2) deluge system to work alongside the existing wet system.

Has anyone heard of this before?

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14 Comments

Dan Wilder

8/14/2024 08:04:21 am

Can you....with the right detection and releasing equipment yes however, a couple issues come up

-Why? Is the intent to increase the density (which would be extremely difficult to prove).

-Reasoning - There is no deluge requirement for protection of electric vehicles, just the increased density which can be handled by the basic wet system

-Water Supply - Will it be able to handle a full wet system remote area and the deluge water demands for the required duration

-Cold Solder - At what point does the deluge trip and what effect will that have if the intent is to provide additional density if the other system cannot activate any further?

-Need for separation - likely going to need some sort of baffles to separate areas....

8/14/2024 08:56:14 am

This comment about the separation / baffles cannot be understated. This is paramount to have a chance at an appropriate water supply duration and response.. in addition to all the other comments found here. My approach to this design would still be similar to industrial deluge where adjacent zones may be required simultaneously and requires a large water supply. This should take into consideration fire/heat spread between zones. If more than 2 Adjacent zones cannot be separated by rated partitions, this could be a deal breaker if looking at 16 sizeable zones.

Anthony

8/14/2024 08:07:52 am

The OH 2 could act as a wet pilot line for the deluge system with proper valving and signaling. I wouldn't but it think it could.

Jesse

8/14/2024 08:12:55 am

My first gut reaction was "What could go wrong..."

My biggest concern right off the bat would be water supply with the potential for OH 2 protection AND EH2 deluge operating simultaneously using the same water supply. You may have a pretty robust water supply and fire pump, so maybe that isn't an issue.

But Dan brings up a lot of other legit concerns, as always. Are we trying to compound the OH2 and EH2 densities into something like 0.60? If so, why not just hydraulically reinforce the wet system to provide the density, and then I'd wonder where that density came from.

This one is pretty interesting.

Glenn Berger

8/14/2024 08:17:33 am

I think that I am missing something here. You want to provide a general area deluge system in the same location as a general area wet-pipe system? Dan's response above raises concerns that I have regarding your question.

I have provided specific application for a deluge spray system in an area with a standard closed head system.

James Phifer

8/14/2024 08:39:16 am

Maybe I'm not understanding this correctly but, this doesn't seem like it would work well. If the Deluge system activates first, that would keep the fusible links on the wet system from activating. If the wet system activates first, that might keep the detection from activating, unless the flow switch triggers activation of the deluge. You would still need to calculate both flows simultaneously.

Franck

8/14/2024 08:56:11 am

It is quite a common practice in turbine building where you have an area protection by sprinklers below the turbine deck, and some spot deluge protection systems for some key oil-containing equipment (feedwater pumps, seal oil skids…).
The deluge is there to protect the hazardous components/equipment while the sprinkler is there to avoid a large spill fire and protect overhead cable trays.
In that case, the deluge nozzles are directed to the equipment and located below the sprinkler level.
But the area covered by the deluge system is quite limited.

In your case, it might be more difficult depending on the additional area covered by the deluge system (as highlighted above) and the position of deluge nozzles (problem if too close to sprinklers as indicated by James.
And of course you need to combine both water demands.

Ricardo Gonzales Jr

8/14/2024 09:05:20 am

I have done this in-flight simulator rooms. The OH2 wet sprinklers were mounted in the ceiling and the deluge were placed 3' from the floor. The units are all hydraulic and the deluge was manual only. The intent was for protecting the cockpits with the sprinklers and if hydraulics were involved in the fire, the deluge to dilute and drain to a separated catch basin where AFFF (3F) is available to extinguish a fire should it travel.

I agree that the system needs evaluation to confirm it can support the flow of both.

Joe

8/14/2024 10:08:31 am

Are there any developments/news on an updated design density to reflect today's vehicles coming to NFPA 13 standard anytime soon? OHII hasn't changed since the 1970's when it was a mostly steel car with little plastic and a steel gas tank. Without adding the EV component, today's car is the opposite that testing data is based upon.

James E. Art, FPE

8/14/2024 03:13:29 pm

2022 NFPA 13 now recommends Ordinary Hazard Group 2, for Automobile Parking Garages, due to an increase in combustible materials in newer automobiles, in lieu of Ordinary Hazard Group 1.

Additional Information: NFPA published report and webinar “Modern Vehicle Hazards in Parking Garages and Vehicle Carriers”, July 2020.

Changes:
Yes, cars contain much more plastic, including fuel tanks,
are more likely to be diesel which is more of a fire hazard,
or have alternate fuel such as H2, Propane, Natural gas,
or Li Ion batteries. Gasoline now includes alcohol, and fuel injected autos are at higher pressures.
Battery autos have fewer fires, but get more press, and can be harder to extinguish, and often rekindle.

I hear in Europe the Fire Dept. may bring a big dumpster,
and put the car in that, and submerge!
Can some one please send some info about that?

Also seeking info about car stackers, esp. 3 high or more.
THANX,

Jim

Joe

8/15/2024 11:16:12 am

Thanks Jim, the triple car stackers are a major issue also with lack of tested/proven design density. Combine the triple car stackers and multiple EV chargers in the same enclosed parking garage and residential apartments above is all we seem to be building in New Jersey in our transit villages. It's going to be one heck of a reactive test to the "engineered solution" WHEN the first fire emergency happens.

anon

8/16/2024 09:05:25 am

I have ran into this as well, solution was to have the area become a room surrounded by full height walls.

Jack G

8/16/2024 09:28:07 am

Good choice. I wholly agree.

Jack G

8/16/2024 09:17:58 am

My main concern would be would both design densities. Deluge usually means “ all in “ open heads like exposure systems. Will the OH 2 system above be activated, I think so, and when the 2 systems are calculated simultaneously, the higher flow and pressure would make the Oh 2 heads flow at a much higher flow and pressure, with the oh2 pipe sizes. ( may read not sufficient )
Closed heads supervisory air pre action would be better for tripping but “ all in also. “
I would also review fm global data sheet 7-15, as they are normally ahead of the curve. Includes a hazard category 3 occupancy from
Data sheet 3-26 for automatic sprinkler protection of non storage properties. Provide small hose stations or appropriately sized fire extinguishers for the hazard.
Provide emergency / automatic shut of of electric to the charging stations ( water flow switch- area detection) emergency notifications.
I would also question whether area should be diked -for protection
From electric shock from charging station fires and batteries in the charging vehicles initially for personnel and fire fighters.

Deluge and Wet Sprinkler System in Same Area?

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