canjoena - stock.adobe.com
Despite the rarity of data center fires, they can devastate your organization when they occur. Good fire protection provides insurance you hope you don't have to use.
Good data center fire protection requires four elements: mitigation, detection, suppression and recovery. This means you have facility elements in place to prevent fires from occurring, alert staff when a fire does happen, put out or control a fire and repair facilities after fire damage.
Mitigation is the easiest and least costly part of fire safety -- but also the most often ignored.
Never store flammable materials, particularly cardboard boxes and plastic packaging, in the data center. These also contain major particulate contaminants you shouldn't bring inside.
Infrared (IR) scan your main electrical connections at least yearly. Varying IT loads can cause wires to expand and contract. IR thermal imaging detects loose connections before they become dangerous, which eliminates one of the major causes of electrical fires.
Smoke detection is a code requirement. To avoid shutting down your data center, you can use dual-interlocked systems with ionization- and infrared-type heads, both of which must activate before alarming.
Even better are early detection aspirating systems that sense smoke earlier than standard heads. The Xtralis VESDA, which stands for very early smoke detection apparatus, and Honeywell FAAST, for fire alarm aspirating sensing technology, are the most common systems used in data centers. These smoke detectors suck air samples through small pipes and can distinguish between smoke and dust.
Early smoke identification enables you to identify and respond to fire threats with portable extinguishers well before standard heads would detect it. Aspirating systems are the least expensive part of any fire control system.
Fire suppression with water
You can suppress fires through a variety of means, although gas and sprinklers are the most common forms in data centers. Most codes require sprinklers, which activate when fire gets hot enough to melt fusible links in the heads and send a deluge of water into the space.
This can greatly damage your data center and present issues related to leaks and malfunctions, so many data centers use dry-pipe, preaction, dual-interlocked designs. In these designs, pipes are charged with compressed air or nitrogen to keep them rust-free, and the system can alert you to leaks before water escapes. Water only enters the system when two detectors alarm, but it doesn't discharge until fire melts the fusible links in the heads. However, the drawback to such systems versus traditional wet-pipe sprinkler systems is that you often accumulate a more significant amount of smoke and fire damage before the room floods with water.
A fog mist system disperses water in tiny droplets that remove heat from fire by evaporation but don't get equipment wet enough to cause harm. Mist also enters cabinets where standard sprinkler water might not and suppresses smoke, which is often as harmful as the actual fire. Local codes determine whether fog mist works as a substitute for sprinklers.
Fire suppression with gas
Gas-based systems come in two types: clean agent and inert gas. Clean agent systems contain chemicals that break the fire triangle by removing heat. Inert gas systems reduce the oxygen level such that fire can no longer burn but people can still breathe.
FE-24 is a halocarbon related to FE-36 that requires no piping change and causes zero ozone depletion. FE-36 is the clean agent used in hand-held fire extinguishers. The most recent clean agent is 3M Novec, which is stored as a liquid and dispersed as a gas. Novec is a non-halocarbon with zero ozone depletion, zero global warming potential and only a five-day atmospheric lifetime. Total immersion liquid cooling systems also use this agent.
Inert gas systems combine atmospheric gases that, when discharged in a closed space, reduce the oxygen percentage to below 15% so fire can't burn but people can still breathe. The most widely known are Inergen -- composed of 52% nitrogen, 40% argon and 8% carbon dioxide -- and Argonite -- 50% each nitrogen and argon. Being atmospheric gases, they cause no global warming and no ozone depletion, but they require a large amount of gas. This necessitates significant storage space for very-high-pressure tanks. Additionally, when suppressed with just inert gas, fires can still smolder and emit smoke.
All gas-based systems can produce noise levels on discharge that can damage high-density disk drives. Most manufacturers can supply lower-velocity heads to help mitigate this damage. All gas-based fire suppression systems also require rooms to be sealed and ceiling tiles to be clipped into place, which means additional construction expense -- a requirement water-based systems do not have.
A hybrid system, such as Victaulic's Vortex system, can combine water suppression with reduced oxygen fire suppression.
Recovery from a data center fire
Data center recovery time is costly. Hard shutdowns of IT hardware mean a full recovery could take up to several days. Damage sometimes requires obtaining and configuring replacement equipment.
Water might be more messy than harmful, provided it doesn't actually enter your hardware, but smoke can be highly difficult to clean up. The best course of action is to minimize your chances of a fire from the outset, have an early warning system in place, and ensure that someone can respond quickly if an alert occurs in the middle of the night.