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What is the state of the art in fire suppression for server rooms? What are the top priorities in choosing a good system?

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closed as not constructive by HopelessN00b, Iain Feb 5 '13 at 16:57


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6 Answers

up vote 68 down vote accepted

Check local fire-codes. Really. In 2003 I was involved in setting up a new datacenter for work. My job was more moving the gear, not wrangling with the architects and contractors who were building it.

Imagine my surprise when I found sprinkler heads in the datacenter during my first walk through. I got about a quarter of the way to indignant outrage before my boss short-circuited me with logic. It seems that local fire code actually covers data-centers, and it mandates sprinklers. I was assured, assured I tell you, that they wouldn't go off unless the FM200 system failed to snuff the fire. I was dubious, but the fire inspectors really did mean that.

Anyway, there are a series of things you need in a fire suppression system.

  • An Emergency Power Off function If there is a fire, the EPO will drop power to the room hard. Yes, that'll cause data damage, but so does fire. If the fire is electrical in nature, this may stop it. Also, if all the gear is de-powered, a water dump does less damage.
  • A sealed room You want sealed for correct HVAC anyway. You don't want to rely on building HVAC unless the building was designed with that room in mind in the first place. Also, this allows you to use...
  • A gas-based suppression system FM200 is popular choice for this. Unlike the halon systems of old, it isn't as environmentally evil.
  • A water based backup suppression system If the FM-200 fails, you need to get the fire out. After the EPO has fired, and the FM-200 dumps, if there is still a fire then you need old fashioned water
  • Water detection sensors in/on the floor If you have any water pipes overhead, you need water sensors in the floor. This is more of an asset-protection thing, but if you DO have sprinklers you need water sensors to detect leaks. Also good for detecting leaks in your HVAC chillers.
  • Call-out capabilities If the fire system trips, you want to notify both Facilities people, as well as data-center staff and management. Obviously, this system should NOT rely upon assets in the data-center that's on fire. This can be hard.

There may be more, but that's off the top of my head. The EPO can be a destructive option, so I don't know how wide-spread they are. But they make all kinds of sense in a room where a water dump is possible.

If you have to retrofit a pre-existing room, some of the above may not be possible. As a fire-inspector once told me, to extingish a fire you need one of three things:

  • Remove the fuel
  • Remove the oxidizer
  • Cool the reaction below the combustion point

The system I lined out above does all three. The EPO removes fuel. The FM-200 partially removes oxygen, but mostly cools the reaction below the combustion point. The water dump smothers the fire due to lack of oxygen, and also cools it. For a high-value asset like a data-center, you want at least two of these.

Because of this, I'd say that your top priority is to see if you can get a gas-based extinguishing system in place as it does far less damage than water does (even with an EPO on your power-distribution-unit or main breaker panel). A truly good system, no matter what the actual suppression technology, has a flexible notification system that allows more than just the facilities supervisor to be notified of the fire-suppression systems activating.

As for hand-held extinguishers, use Class C. But be careful. Dry chemical style extinguishers blow a powder everywhere. And that powder is somewhat corrosive. In the typical high airflow data-center, a fired extinguisher's residue can get everywhere. If the powder gets inside server intakes, it can cause higher equipment failure rates for the next several years. We've had demonstrations of extinguishing fires at our workplace, and have seen how messy it can get. When you buy your extinguishers for in-center usage, use the gas-style Class C extinguishers.

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That says about everything. When I was touring some local data centers for colo, the more professional one's had EPO's & FM200 type systems and I think also the water. They didn't allow anyone to place their own UPS's since they couldn't control the EPO then. They provided 2 independant UPS's though so it wasn't an issue. I've read reports that you can pretty much submerge de-energized equipment in fresh water and once try it will power right back up. –  SpaceManSpiff Jun 14 '09 at 14:33
I've also read that water sprinklers are pretty safe/less damaging when combined with EPO. One thing to remember is that the sprinklers should be dry-pipe and not pressurized so that busted heads or leaks aren't accidently released into the data center. Also to mention, larger rack mount UPS units often have a remote EPO circuit so that they can be hard powered off when the EPO is hit but that still leaves live batteries in the middle of your racks which would be their own fire hazard. –  mtinberg Oct 9 '09 at 23:00
One thing that is frequently missed, especially in retrofits, is that the power-off should also shut down and kill power to the air handling equipment. This also helps keeps the mess down if you decide to attack the fire with a fire extinguisher. –  longneck Sep 10 '12 at 23:38
Also, if you have something like FM200 or Inergen that doesn't require cleanup after a discharge, you may be better off triggering a manual immediate release of the FM200 or Inergen. Cost of recharging those systems may be less than the cleanup of a Class C extinguisher. –  longneck Sep 10 '12 at 23:39
Just a nitpick: An emergency power off does not remove fuel. EPO removes an ignition source. If you have a self sustaining fire cutting the power will not put it out (per definition), and the fuel/oxidizer/heat rule is about fighting self sustaining fires. Removing fuel is done, for example, by cutting a feeding gasoline pipe to a burning generator. –  pehrs Apr 11 at 8:17
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It's bringing this thread back from the dead, but I wanted to add my two cents to this question.

Novec 1230 from 3M is great stuff also. It's a liquid fire suppressant that's:

  • Non-conductive
  • Evaporates harmlessly (and is broken down by UV light as it evaporates)
  • Doesn't damage paper

It truly is amazing stuff. You can drop a textbook in it and it'll be okay. A cellphone will ring while immersed in it. If I were the one setting up a datacenter, that's what I'd use. It's expensive, but so is losing data and servers.

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It's not a thread in the forum sense. These sites are for people to come to get answers. This topic is an important and ongoing one for any admin. Your answer provides great additional information. Thanks for your contribution (and a +1 for you, too). –  Dennis Williamson Oct 15 '09 at 2:30
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All server rooms should have a Class C fire extinguisher outside the main door. You can grab it on the way in, or on the way out. Depending on the size of your server room, get another to stick on the far side as well. And keep them charged/inspected once a year.

FM200 seems to be a popular choice, halon has been outdated over environmental and health concerns. If your server room cannot be sealed, I think you will have issues with a gas technology (like FM200).

You should call up a vendor and ask about their services and products. Get the dimensions of your server room, and any other odd factors (HVAC, vents, etc.) before you call. Most vendors will be happy to assist you, just don't agree to buy anything until you're ready.

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One thing worth mentioning is that


I know of two cases where a flooding was triggered and caused a lot of havoc. The reason seems to be that the outlet pressure is often much higher than assumed. At one place, it (the flooding from below the DC floor) sent old IBM terminals flying off the top of the racks into other racks. The other place didn't end up as lucky, with the exit valves being shot through the storage libraries walls. They had another problem, the pipes need to be cleaned after installation. Otherwise they may contain oil and metal remnants. Thats what ended up in the tape libs' inside, doing some extra damage. (I know this really happened as described since I heard it from one security guard and a tech from a tape vendor. They wasted ˜50 drives getting relevant data off the messy tapes)

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The top priority in choosing a system is having your particular location surveyed to find out what is suitable, and also making sure you can afford the ongoing maintenance for such a system. Oh and not neglecting small hand-operated fire extinguishers for smaller incidents too.

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Which ever system you go for, get an active DR site as well. I have seen more outages due to events triggering the EPO than fires (Fires 0, triggered EPOs 2).

This does include one caused by the Electrician mistaking the EPO button for a door exit button. I've dealt with sites that use Inergen and FM200. Both seem to be good solutions.

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The EPO switch should be covered with a transparent (typically plastic) unlocked case. Also to prevent accidentally being knocked. –  mctylr Mar 16 '10 at 15:30
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