Exploring
Fire Protection and Security
Suppression
A number of different types of suppression systems have been used in cultural institutions over the years. Modern wet-pipe sprinkler systems are increasingly recommended for cultural institutions due to their relative low cost, ease of maintenance, and dependability.
The rate of accidental sprinkler discharge has been estimated at 1:1,000,000 heads or better, and studies have indicated that 70% of library fires are extinguished by three or fewer sprinkler heads.
Sprinkler Systems
Water sprinkler systems consist of the sprinklers themselves, the piping system, and a water source. Systems are usually also equipped with water flow alarms (to indicate when a sprinkler is activated), control valves (allowing the system to be shut down), and features that allow the pipes to be drained for maintenance and tested periodically.
In modern sprinkler systems, only the sprinkler heads nearest the fire are discharged.
Sprinkler heads are activated by high temperatures. In modern systems, sprinkler heads operate independently of each other; only the sprinklers in the immediate vicinity of the fire are discharged. On/off heads that close when the temperature is reduced are available, but they are not generally recommended due to their high cost and the fact that fire personnel normally arrive to shut down the system before the temperature is reduced enough to close the sprinkler heads.
There are three main types of sprinkler systems:
- Wet-pipe systems are the most common, the most reliable, and the easiest to maintain. Water is maintained in the pipes at all times, and when a sprinkler head opens it is discharged.
- In dry-pipe systems, the pipes are filled with air, which is released when a sprinkler head opens, allowing water to flow into the pipes and to the fire. These have a slower response time, but are useful in areas where freezing of the pipes might occur.
- Pre-action systems work with the fire detection system; when some combination of detectors indicates a fire, a valve is opened to allow water into the pipes. The water is not discharged, however, until a sprinkler head is activated. These systems are expensive to install and maintain, and they have a higher risk of malfunction.
Water Mist Systems
In recent years the water mist system has emerged as a new fire suppression option. These systems discharge water in very fine droplets at high pressure, which maximizes the water's cooling capacity and suppresses the fire with much less water than conventional sprinkler systems.
A typical sprinkler uses 25-72 gallons of water per minute; water mist systems in testing have extinguished library and archival fires with only 1 to 5 gallons of water; and fire department hoses typically deliver 100-500 gallons per minute.
Gas Suppression Systems
Gas suppression systems extinguish a fire by flooding a space with some type of gas to reduce the oxygen concentration so that insufficient oxygen is available to fuel the fire. They can only be used in storage areas, because they pose the danger of asphyxiation to people.
In previous years, numerous institutions installed Halon gas suppression systems. New production of Halon has been phased out (due to its effect on the environment), and while several substitutes have been developed, none has emerged as a completely satisfactory replacement. Options include FM-200 and Inergen, both of which are costly and must be used at high concentrations, requiring the storage of large amounts of the gas.
Fire Extinguishers
Using a fire extinguisher is harder than it might seem; proper training is essential.
Fire extinguishers are rated according to the types of fire they put out. Class A extinguishers are used for ordinary combustibles such as wood or paper. Class B extinguishers are used for fires involving flammable liquids (e.g., oil, grease). Class C extinguishers are used for electrical fires.
Dry chemical extinguishers (also known as ABC extinguishers) are usually rated for multipurpose use. Water extinguishers (standard or mist) should only be used on Class A fires. CO2 extinguishers are most effective on Class B and Class C fires. Staff must be trained in the use of fire extinguishers, and extinguishers must be inspected annually.
