Fire suppression

[dinowuff]

Just curious as to what fire suppression AO Members use in their data centers.

Currently, I have forced water sprinklers. And a few c02 extinguishers.

Now I'm not exactly happy with water but what else is there? Insurance and building codes state there must be water, or an acceptable substitute, in all mechanical closets. That's how the date center is classified. Of course neither the insurance or city/state folks will tell me what's an acceptable substitute.

[MrLinus]

I would think that Halon systems (Halon 1301 and FM 200) would be acceptable substitutes. I found this website with some whitepapers that talk about different types. Basically they are safe chemical fire suppression extinguishers, and, AFAIK, have been the recommended type for computer data centers.

[dinowuff]

Thanks for the link MsM, is Halon used at your school?

[MrLinus]

I'm not sure. I think at our particular campus it's not but at the main campus I believe it is. The main campus would have more of the critical servers located there. I have worked at other locations where it was used (I wasn't in charge of it or the installation --- this was during my tech support days)

[|3lack|ce]

Halon's good, however there's a high chance of 'reflash' occurring when the space is ventilated and oxygen returns. To understand which extinguishing system to use, one must first understand the fire triangle and how it works:

To have fire, you must have Fuel, Oxygen, and Heat. To extinguish fire, one need only remove one of these three elements. Should that element return, the fire will reflash. Water removes heat, CO2 removes heat and oxygen, halon removes oxygen, Potassium permangenate (pkp) removes heat. Each of these are quite effective in extinguishing certain types of fires, and each has its own hazards -

Water, of course, will short out any and all electrical gear it comes in contact with. If you're willing to fry your servers to save your building, this is the way to go. It has a very low chance at reflashing unless the fire is 'deep seated' in the burning material (embers too deep for the water to cool).

CO2 is the wisest choice for fires of an electrical nature, and can be used on some types of material fire as well, just not as effectively. Its effect of removing oxygen is secondary - the primary effect of CO2 is cooling. It leaves no residue and won't harm an electrical circuit, even when shot directly onto or into it.

Halon is best used in fires involving tightly enclosed spaces. Since Halon is an oxygen displacer, the space to be extinguished must be saturated with it. It has a high percentage of reflash on reventilation, since at that time it's function is defeated. Wait a long time before opening a space where you've used halon to give time for the fire to fully cool. Wait longer after opening the space to allow the oxygen to return before re-entering.

PKP - purple K powder - is outstanding for halting almost any material fire, but is especially damaging to electrical gear in that it leaves behind a corrosive residue. It is ineffective on chemical fires because it doesn't float. Its primary function is the formation of a 'heat barrier' between the burning material and the fire itself. It has a low chance of reflash.

Based on this knowledge, I suggest Halon for your server closets (if your company can afford it, a Halon system is somewhat expensive to set up), and CO2 for everything else electrical. Stay away from dry chemical extinguishers (these contain pkp which will destroy your gear), and avoid water for the same reason.

[dinowuff]

Thanks Ice.

I am going to start researching Halon solutions for my server room. Your statement about reflash causes concern as my server room has its own ventilation system. Don't know if it can be shut down in case the Halon system is deployed. As I understand your explanation of the fire triangle, running the air conditioner after extinguishing a fire would be a bad idea.

Again, Thanks MsMittens and BlackIce

[MadBeaver]

My company has Halon systems in all of our data center.

When the system comes on all ventalation is sealed off and will only open when the alarm and fire suppression systems are reset.

If you use water suppression and there is a fire, the water will destroy equipment whether it stops the fire or not.

[cacosapo]

inst Halon banished due to be a CFC gas?
I thought that FM200 came to replace Halon because of pollution problems.
I used to run a Data Center here (3 places) - all with FM200. Good solution - but kinda expensive (here at least). At least it dont kill you if you happens to be inside the Data Center when a fire starts

[|3lack|ce]

Dino - sorry about being so late in further response - RL constraints had me busy -

A good Halon system will turn off all venilation into a space automatically - it's especially good on spaces with separate ventilation, so you're already halfway there.

I'm not sure on Halon 1301 being banished due to CFC's - my information is a bit dated since I haven't had DC Firefight training or refreshers since 1992 - cacosapo might be right on that, and it's most definitely worth looking into. I honestly have no clue about FM200 - never used or heard of the stuff and it probably wasn't invented yet back in my Navy days...

[MrLinus]

There are variations of Halon that don't have CFCs. FM200 is one and I thought some other variations were others. You cannot buy Halon-CFC based suppression systems anymore, unless you are deemed "critical" (e.g., military). I did find a nice FAQ that seems to cover this.