Fire Suppression (Water Mist) Metalclad M/V Switchgear

[gd008]

Can anyone provide me with information on water mist fire suppression systems. I have previously read an article where water mist jets were installed in the air insulated bus chamber of 11kV S/G for extinguishing fire. I would appreciate any information on this type of system.

 

[jraef]

Water used in suppression of an electrical fire????
Sounds bogus to me!

"Venditori de oleum-vipera non vigere excordis populi"

 

[gordonl]

I've had the pleasure of attending a few switchgear burn up's, and I haven't seen a fire that was self propogating of any magnitude. Once the fault is cleared most of the damage is done, and spraying water wouldn't prevent be of much value. I would be afraid of the water sprays causing more damage causing faults when the problem may only be an overheating or melting item.

I have seen smoke detectors installed directly above, but not water sprinklers.

Of course oil dilled equipment is another issue.

 

[jbartos]

Suggestion: Try CO2 snow instead

 

[alehman]

Water-mist systems are commonly used as an alternative to gaseous clean-agent systems such as Halon or FM200. They are also used where water supplies are limited or where normal high volume fire sprinklers may cause excessive damage (eg data centers). They use a very small amount of water, dispersed by special nozzles at high pressure which basically makes fog.

See

http://fire.nist.gov/bfrlpubs/fire94/PDF/f94184.pdf

 

[busbar]

Aside — AFFF has been used in large pulsed-power research facilities, but I've not witnessed related post-discharge mopup.

http://fire.nist.gov/bfrlpubs/fire02/art130.html

 

[jraef]

Intersting reading. It does say that tests were done on LIVE switchgear, but only after the power was cut off. If you ask me, that in and of itself is an oxymoron. It goes on to say that "... The switchgear bays became fully operational when dry". I find this difficult to swallow; "operational" is one thing, safe is another. In the real world, who is going to decide on when it has become dry enough and safe to reenergize that gear?

And consider the potential of a leak in the misting system while the power was on! I will not entertain the arguments that "it won't leak". That is just a challenge to good 'ole Murphy.

"Venditori de oleum-vipera non vigere excordis populi"

 

[busbar]

jraef, that is a good point. I'll bet the ‘3-6% additive' does not hasten evaporation, much less decrease conductivity of the medium. Seems kneejerk reaction to Halon [via the Montreal Protcol] tended to promote hasty {but surely politically correct} support of "new and improved."

 

[alehman]

It's interesting that ANSI requires an automatic power disconneting means in elevator machine rooms, to be activated based on heat detectors set at a temperature lower than the sprikler heads. So far as I know that rule has only ever been applied to elevator equipment.

 

[jbartos]

Suggestion: Visit

http://www.reliablefire.com/co2folder/co2systems.html

http://www.fike.com/co2_com_products.html

http://www.fike.com/marine_applications.html

http://www.getzfire.com/Engineered/CarbonDioxideFireSuppression.htm

http://www.nafed.org/library/whyCO2.cfm

etc. for the CO2 based fire extinguishing alternative to water mist

 

[jbartos]

Suggestion: Visit

http://www.nafed.org/library/wmist.cfm

for: usage of non-conductive water for the water mist (distilled water)