Nova Fire Protection, Inc.
Types of Fire Sprinkler Systems

Wet Fire Sprinkler Systems
A wet fire sprinkler system is the most common sprinkler system type used in homes, offices, and condominium buildings. In wet systems, the piping is filled with water that remains under constant static pressure. When a fire occurs, the sprinkler closest to the heat source will open and immediately discharge water. Most fires are suppressed or extinguished from the activation of just a single sprinkler head.

Dry Pipe Systems
A dry-pipe system operates in a similar manner to a wet system, however, instead of the piping containing water under pressure, air is used instead. The system water is held back further down the piping behind a Dry Pipe Valve. When a fire occurs and a sprinkler opens, water is released from behind the Dry Pipe Valve and rushes to the open sprinkler within seconds. At this point, the dry-pipe system extinguishes the fire just as a wet system would. Dry-pipe systems are installed in lieu of wet-pipe systems when the area of coverage is subject to freezing temperatures, such as in an attic, garage, balcony, and outdoor living spaces. 
Anti-Freeze Systems
Anti-freeze systems are virtually identical to a wet-pipe system, except a mixture of anti-freeze chemicals are added to the water to protect from freezing. This type of system is installed when there is a large coverage area that is subject to freezing temperatures, such as unheated parking garages, warehouses, or barns.

Pre-Action Systems
Pre-action systems are similar to dry-pipe systems, because the water is held behind a valve and only pressurized air is in the system piping. Pre-action systems come in many varieties, but a common component is that two separate events must occur in order for the sprinkler to open and discharge water. Pre-action systems are installed when the coverage area contains items that require increased protection, or are easily damaged by water, such as network servers, electronic machinery, or hospital equipment.  

Deluge Systems
Deluge systems contain sprinklers that are all ‘open’, which means that they do not have individual heat-sensing devices. The piping in a deluge system is dry and the water is held behind a valve further down the piping. System sensors open the valve and release water when they detect heat, smoke, or flames. Since all the sprinklers are ‘open’ in a deluge system, all of the sprinklers discharge water simultaneously. Deluge systems are used in coverage areas that are susceptible to the rapid spread of fire, such as in paper manufacturing and airplane hangers.