Type of Deluge Protection for Transformers?

11/9/2020

We have a project where transformers are located on the periphery within a building's ground floor. There are 14 transformers within a single room. The life safety consultant has recommended for us to provide deluge system protection.

Is it required to provide a deluge valve for each transformer, or combine three or four transformers per valve?

Also, how should sprinkler flow demand - is it calculated by each nozzle, or should we consider the entire transformer area for protection? Under NFPA 15 we have assumed 0.25 gpm/sqft (or 10.1 lmin/sqm).

Thanks in advance.

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6 Comments

GLENN BERGER

11/9/2020 10:25:13 am

Need additional information prior to responding!

14 Transformers within the same room? Are they oil-filled transformers? Are they using the Less-Flammable Fluid? Are there fire barriers between some of the transformers?

Mike

11/9/2020 10:25:18 am

You can protect multiple transformers as long as adjacent systems that may be actuated are calculated simultaneously.

The zoning of the systems depends on the maximum demand balanced with your water supply.

Justin Milne

11/9/2020 10:56:19 am

Is this a military, proprietary, or industrial job? Depending upon this, answers could be different.

Dan Wilder

11/9/2020 11:20:03 am

Are these transformers just the incoming SES and distribution equipment? I've had "Less Flammable Liquid Insulated Transformers" within buildings that were only protected by OH2 (overhead only) and curbing for containment (the building code dictates limits for the actual volume of liquid able to be within the building). Having this many within a room utilizing a deluge system would be a containment nightmare and depending on arrangement, would be better handled by individual valves per unit vs. having to combine multiple zones for simultaneous activation.

If these are the larger oil-filled transformers, I have never seen them within a building due to the required clearances for the high voltage, only on the exterior and then they start at a .3 density per FM 5-4, .25 per NFPA 15 (if I remember correctly).

Franck

11/9/2020 12:05:29 pm

As already indicated, it all depends on the size of your transformers.

I do hope that they are not large size units if you have 14 of them within the same room.

The density is 0.25 gpm/ sq ft, but the area of application is not the ground floor, but the entire surface (5 sides) of the transformers (for large units it may become a huge area of application for each).

If you have several units covered by one valve, it means that the fire on one unit will wet the other ones at the same time, which might not be desirable.More water = more water damages and more water to collect.
On the other hand, if you have one valve per transformer, the cost of installation will be huge.
Note that for the demand, as transformers seem not to be fire separated in your case, you may consider the activation of several deluge at the same time for your water demand. If a transformer start to burn, it may trigger the deluge systems on adjacent units at the same time. Which means that you may consider 3 deluge systems operating at the same time !!!
Unless transformers are all located in separate fire cells.

To be honest, if they were small units and you can provide some fire separation in between each units.

Recommended practice for oil-insulated transformers of greater than 380 l (100 gallons) oil capacity installed indoors is that they should be separated from adjacent areas by fire barriers of 3-hour fire resistance rating. This includes the separation between transformers.
Where transformers are protected by an automatic fire suppression system, the fire barrier fire resistance rating is permitted to be reduced to 1 hour.

11/11/2020 10:05:38 am

As long as cumulative demand of all transfer together should not exceed over 2500 gpm, you can cover multiple transformers. This is maximum allowed limited which can be supplied from single deluge valve.

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