Automatic fire protection systems work to slow the spread of a fire without the need for manual assistance or activation. Once a fire or smoke alarm goes off, the system automatically begins to put out the fire, or slow its spread through the building. These automatic fire protection systems help limit property damage and often allow more people to exit the building, reducing the number of injuries or deaths. While most fire suppression systems are found in commercial structures, some building codes may require sprinklers or other protection devices in residences as well.
Wet sprinkler systems are the most common type of automatic fire protection system. They consist of water-filled pipes that run through the ceiling of a building, with sprinkler heads placed in the ceiling at specified intervals. Each head contains a fluid-filled bulb, which bursts when exposed to high temperatures, allowing the water in the pipes to flow from the head. Contrary to popular belief, only heads exposed to high temperatures will activate during a fire, which helps to limit property damage from water.
In a deluge system, all the heads work together to put out a fire. This type of automatic fire protection system consists of water-filled pipes activated by either smoke alarms or temperature gauges within the building. During a fire, all heads release water to douse the flames quickly and effectively. Deluge systems are most commonly found in high-risk facilities, such as chemical or industrial plants.
Some applications require a dry pipe, or pre-action, system instead. In a pre-action system, the pipes are filled with air rather than water. The system requires two separate signals before water will be released from each head. An initial smoke alarm or manual input alerts the system to fill the pipes with water. Once each head is exposed to sufficiently high temperatures, the bulbs burst to allow water to flow from the head.
Museums and libraries often rely on either a pre-action system or a chemical-based fire suppression technique. In chemical-based systems, the sprinkler heads release dry chemicals or gas to smother a fire. This limits water damage to sensitive or irreplaceable objects like paintings or books. This type of dry chemical sprinkler system often includes Halon gas, though Halon is generally being replaced by more eco-friendly products. Dry automatic fire protection systems may pose a health risk to occupants in some applications, and are typically found in unoccupied parts of a building.