It might seem odd that a discussion of fire suppression systems occurs in a section on preventive controls. But consider that an effective fire suppression system can help prevent the destruction of your information infrastructure and, more importantly, injury to your employees.
A common type of fire suppression system is the ubiquitous fire extinguisher. Fire extinguishers are not intended to serve as your primary means of containing facility fires. Instead, their purpose is to assist in getting personnel out of affected areas.
Mount extinguishers in plain view. Train one or more of your employees in their use. Quarterly inspections by a certified fire extinguisher servicing agency or company should be an essential part of your fire suppression strategy.
Another important consideration is the deployment of the proper types of extinguishers. For instance, the type of fire extinguisher installed in your data center may not be appropriate for a manufacturing plant floor. Table 1 lists fire suppression system classes and the types of fires for which they're intended.
We've established that fire extinguishers are not intended to actually suppress a large scale fire in your facility. That's the function of a fire suppression system integrated into your building's infrastructure. This type of system is designed to quickly distribute a fire suppression agent over a large area. Two major types of systems that fall into this category are water and chemical.
Water systems are an effective, inexpensive solution for areas where Class A fires are common. Your general office area is a good example. Water-based suppression systems deliver water to a fire via standard sprinkler heads or by using deluge style heads. Deluge solutions deliver large amounts of water quickly. In addition to how the water is delivered, there are two approaches to how a suppression system stores water - wet pipe and dry pipe.
Wet pipe systems store water in the pipes feeding delivery heads. The advantage of this approach is the lack of delay in getting the water to where it's needed. The disadvantages associated with using wet pipe systems include:
- Water freezing in the pipes if proper environmental controls are not used or available
- Condensation build up causing water damage to computer equipment
Dry pipe systems help solve these problems. In dry pipe systems, valves prevent the distribution of water into the pipes feeding distribution heads until a fire is detected. Upon detection of a fire, the valves open and water flows to the heads for release. This type of system is ideal in areas where pipes may freeze or in data centers where water damage from leaks or condensation may occur.
Although water-based systems are typically less expensive than chemical delivery systems, they are not the best choice for data centers. Aside from the fact that water delivered to extinguish a fire may cause more damage than the fire, there is the problem of false positives by your fire detection sensors.
More than once I've been involved in dealing with fires that didn't exist. Fire detectors are not infallible. In one instance Inergen, a chemical suppression agent, was delivered to my data center because two detectors under the raised floor interpreted a cooling unit gas leak as the presence of a fire. It took 14 hours to clean and bring the systems back to full production. If water had been delivered instead, it may have been necessary to transfer to our hot site until I could assess and replace my 250 servers, storage arrays, etc. If your budget requires the use of a water delivery system, consider the installation of a preaction solution.
Preaction water delivery solutions are very similar to dry pipe systems. The difference lies in what happens after the water is distributed to the distribution heads. In a preaction system, the suppression agent is not immediately released. For example, the actual presence of a specific level of heat might be necessary before water is dispensed to affected areas. This provides time to take steps to cancel false alarms.
Chemical delivery systems are a much better choice to protect your data center. Since no water is released, there is little or no damage to critical systems. Recovery is faster, and the loss of critical data is minimized. Agents used in non-water systems commonly include FM-200, Inergen, and CO2. The primary disadvantage associated with the implementation of a chemical-based system is cost. However, the additional cost provides the assurance of a reasonably quick recovery following a less than catastrophic fire.
