Standard(s) for Deluge Transformer Protection?

7/23/2020

Good morning, I have a project with a 60MVA outdoor transformer. We have a deluge valve system with wet pilot trim.

Is there a standard requirement for protecting the transformer regarding k-factor, coverage area, and distances for a sprinkler/nozzle from the transformer?

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4 Comments

Dan Wilder

7/23/2020 09:46:43 am

NFPA 850 gives guidance along with FM Global Standard 5-4. Nozzles are MFG specific as to angle of spray, surface area coverage, and effective reach (based on the angle of the angle of the nozzle). K-Factor isn't as much an issue other than ease of use in the field and refining calcs to prevent over discharge. The pilot line has some requirements as well so don't forget it when you start laying out pipe stands.

The FM guidelines are pretty clear on where not to spray (bushings, face of control panels) and there will be coordination for the containment size for discharge. NFPA 13 & 15 will also need to be referenced for pipe stand requirements and don't forget to brace i...a lot. Those things like to move and shake when the valve gets tripped.

franck

7/23/2020 10:56:07 am

As indicated by Dan, no specific requirement for K factor.
NFPA 850 is good, as well as other documents mentioned by Dan.
The key thing is to cover the entire surface (surface protection) with a minimum density of 0.25 gpm / sq ft. This will determine the number of nozzles depending on K-factor and angle.

2 issues I often see :
- lack of coverage for the conservator (expansion tank, normally located above the transformer) - it should also be a surface covering
- distance of nozzles too far from transformers - many suppliers recommend a maximum distance of 2 feet for outside transformer because of the possible adverse effect of wind

Mike

7/23/2020 04:51:49 pm

NFPA 15 provides density, application rate drainage requirements.

Spacing and k factor is dependent on the manufacters data of the nozzle.

Most common is Tyco D-3.

Also provides guidance for spacing and location of pilot heads.

MHK

7/23/2020 05:58:57 pm

The Viking's water spray system design manual also includes some information of the water spray system design for transformers.

https://www.vikinggroupinc.com/sites/default/files/databook/deluge/designdata/042602.pdf

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