CO2 Fire Supression Inside Switchgear & MCC? 1

[rcw retired EE]

Our client is requiring each "switchgear cubicle and MCC cabinet" to have automatic CO2 fire suppression. That means a detector and a discharge nozzle in each "cubicle".

Has anyone ever seen 15 kV or 600V switchgear or MCC's with CO2 protection? Not an electrical room with a Halon or CO2 flood system, but CO2 piped to each switchgear section.

My initial reaction is that all of the CO2 piping and detector wiring will cause more problems than the CO2 cures. (I have repaired switchgear faults caused by fire detection equipment.)

I believe this is from an insurance company's misinterpretation of NFPA 850 7.8.1.3

 

[alehman]

NFPA 850 discusses protection within equipment enclosures, but only in the section on computer and telecommunication equipment. I've seen this for large media storage systems where special suppression agents are required to avoid damaging the media.

Never heard of suppression within switchgear. Sounds like a bad idea to me. I'm not sure you could even make the enclosures sufficiently airtight for gaseous suppression to be effective.


NFPA850
5-8.1.3
A preaction sprinkler system for the computer or telecommunications rooms should be considered during the fire risk evaluation. In addition, total flooding gaseous fire extinguishing systems should be considered for areas beneath raised floors that contain cables or for areas or enclosures containing equipment that is of high value or is critical to power generation. Individual equipment and cabinet protection could be considered in lieu of total flooding systems.

5-8.4 Switchgear and Relay Rooms.
Switchgear rooms and relay rooms should be provided with smoke detection systems.

 

[itsmoked]

I can see it now.

The enclosure door decapitating the unwitting service man due to 800Cuft of high pressure gas being instantly dumped into a 4 cubic foot box...

 

[dpc]

We have done halon systems inside large control panels. We have also had to sprinkler electrical rooms in many instances.

I have not seen a CO2 system inside electrical equipment. I would think they would want an FM200(?) system (or whatever the successor to Halon is)

 

[alehman]

FE-227 (FM200) may be a good choice because it is effective at fairly low concentration (I think 7% is the number, if I remember right). Gases such as CO2 and Inergen require much high volume, which means more air is displaced and more liklihood of damage and flying parts.

The one thing to keep in mind with CO2 is that it is quite lethal when concentrated enough to be effective at fire suppression.

 

[itsmoked]

But it do cool things down below combustion temps FAST!

 

[EEJaime]

We have had success with fire suppression systems such as FM-200. We are no longer allowed by code to use Halon due to environmental concerns, and it seems that introducing Carbon Dioxide into the interior of a switchboard is a really bad idea. CO2 at the temperature and pressure at which it would be delivered, coming in direct contact with busses, lugs, cables, instrumentation, etc...? Even at normal operating temperatures I think a sudden drop in temperature will damage insulation, deform small components and stress connections. At temperatures sufficient to trigger the release of a suppression agent? I don't think you will find many manufacturers whom will support this type of installation. I certainly don't think this is part of UL testing.

Release of FM-200 into a switchgear room should be sufficient to quench any 'normal' types of fire incidents. I would certainly recommend discussing this with the switchgear manufacturer's first. And possibly get the client to participate in these discussions if it is his wish to introduce this feature. I would also make sure you recieve clear written direction if he insists on proceeding with this.

Best of Luck,

 

[itsmoked]

I second EEJaime's suggestions to talk to the manufacturer with the customer and get it in writing! Those are great ideas!

 

[rcw retired EE]

Thanks for the input confirming what I thought. A coupleo f switchgear suppliers have said they could not / will not install the detectors and CO2 nozzles in their gear. We will probably end up with a full room CO2 system with a pre action alarm. The CO2 system willbe quite large!

I appreciate the help.

 

[itsmoked]

And dangerous to humans.. With all these turn off before entering and don't forget to turn it back on when you leave rules. yuck. But yah gotta do what you have to do..

 

[EEJaime]

I agree with Itsmoked that CO2 systems bring with them increased liability concerns insofar as their possible adverse effects to occupants. We use the FM-200 systems for MRI computer rooms, Co-generation switchgear rooms, Boiler and Chiller control and command rooms, data centers, etc.... They are expensive, but they are safe and reliable and cleanup is simpler. You may want to consult a Fire Protection engineer in your area to take a look at your installation and make a recommendation.

Again, best of luck with your project.

 

[cuky2000]

As minimum, switchgear room should be designed for fire resistance to meet code requirement and withstand the heavy forces created by sudden hot gases expansion during a short circuit event.

Most switchgear designed for the ANSI marketplace is not seal tight. Fire detector and discharge nozzle in each cubicle may not be effective and doubtful that survives the high temperature and violent sudden expansion of gases as shown in the picture below.

http://cuky2000.250free.com/SWGR_SC_Test_1.gif

If you have to include additional protection, consider an approved arc detector sensors In lieu of fire sensor and nozzle inside the switchgear cubicle. For details see the enclose links.

http://www.ceerelays.co.uk/brochures/UTU Arc Protection.pdf

http://www.abb.cz/global/czabb/czab...ddbc1256efa003f626f/$FILE/Katalog TVOC_EN.pdf

 

[itsmoked]

Darn! cuky I wanted to see that too..

 

[cuky2000]

Itsmoked,

I reduce the size of the file to less than 250 kB. This is the price to pay when using free storage sites.

I am hopping you like the colorful sparks in the swgr.

Best regards/Cuky2000

 

[itsmoked]

heheheh. Thanks cuky2000! I always like a good blast.

 

[dualrobin]

I have not seen a CO2 system in 13.8KV switchgear but I have seen a FM-200 system with heat detectors and discharge nozzles. The suppression pipe work and nozzles were located in the auxiliary compartments only and not in the high voltage busbar sections. This switchboard was located in Saudi Arabia, however American construction companies were building to American standards. This scheme was only in the 13.8KV switchgear and not LV MCCs.

 

[itsmoked]

Seemed to me once, that I thought, that maybe, I heard somewhere, under a blue moon,(are you getting the gist yet?) that CO2 powder was conductive. Anyone know if this is true? It would probably alter one's thoughts about spraying it into electrical panels.

 

[cuky2000]

According with several sources, CO2 has a good dielectric strength. In fat, many researchers consider the CO2 as an alternative to replace the SF6 as dielectric media for high voltage circuit breakers. Several fire suppression vendor advertise that CO2 disperses leaving no material trace or none conductive residual.

The major drawback for Carbon Dioxide is the dangerous in areas occupied by personnel, if applied in concentrations of 34% or greater.

 

[dpc]

I'm not sure this would even be legal due to safety considerations in an occupied space unless it could be assured that the CO2 concentration stays at an acceptable level.