Deluge Sprinklers for Oil Transformers?

10/30/2019

Sorry - seems to have missed the question posted for this one. If you received a blank email today, my apologies. Now onto the question:

Where can I find guidance as to whether or not an oil transformer requires sprinkler protection? I'm specifically looking into standards or requirements concerning deluge sprinklers for oil transformers. Thanks in advance.

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3 Comments

Franck Orset

10/30/2019 10:27:12 am

What is exactly the question ?
Of course, deluge protection for outside transformers is an adequate solution. Density is 0.25 gpm/sq ft over the entire surface of the transformer (do not forget to adequately cover the entire surface of the conservator tank) and 0.15 gpm/sq ft for the ground protection. Nozzles should not be located too far from the surface to be protected (with some manufacturers, max. distance should be 2 ft) as strong wind may interfere with an outdoor deluge water discharge pattern.
For transformers located inside rooms (smaller units), a sprinkler protection, with the same design density (0.25 gpm/sq ft) can be considered.
Activation of the deluge system should preferably be done by a pilot line.
You can have more information in NFPA 15 and NFPA 850.

Franck Orset

10/30/2019 10:33:07 am

Our comments seem to have been addressed at the same time :).

Have a look at NFPA 850.
Normally, the necessary requirement is a safe separation distance and/or an adequate fire wall between the transformers or between transformers and adjacent buildings (50 ft for larger units).
The deluge protection is an additional feature, normally to be provided if the safe separation or fire wall separation is not sufficient.
But many insurance companies require both (safe separation AND deluge protection).

Note that the deluge protection will not prevent the transformer to explode in some adverse conditions (blowing up the deluge piping system). In that case, the safe separation distance is the only protection for your adjacent structures/equipment.

For indoor transformers, a sprinkler protection is normally a good idea, especially in rooms housing several units. But again, if each transformer is located in a separated fire cell and are easy to replace (small units) a smoke detection system might be considered as sufficient.

10/30/2019 10:46:08 am

"Where can I find guidance as to whether or not an oil transformer requires sprinkler protection?"
Generally, it comes to the point how much losses and damages you are willing to accept as a result of loss. IEEE979 Guide for Substation Fire Protection based on industry standards and good practices; NFPA850 is a recommended practices;
FM - 5-4 is loss prevention recommendations. As you can see there is nothing for direct requiremetns.

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