Common types of fire sprinkler systems: 

Wet Pipe System: A piping system connected to a water source and filled with water so that water discharges immediately from sprinklers fused by heat from a fire.

This type of system is the most common type and used everywhere freezing is not a issue.

 Dry Pipe System: A piping system connected to a water source and filled with air pressure supplied by a compressor. When a sprinkler is fused by heat from a fire the air is expelled first allowing a special check valve, called a dry pipe valve, to operate thus allowing water to flow into the piping and out any open sprinklers.

This type of system is used in areas where freezing is a concern. For smaller systems an antifreeze system or "loop" off of a wet system may be suitable. 

 Antifreeze Sprinkler System: A piping system connected to a water source and filled with an antifreeze solution. The antifreeze solution discharges first and then water immediately from sprinklers fused by heat from a fire.

This type of system is used to protect smaller areas subject to freezing and is similar in application to that of a dry pipe system. As a rule of thumb we like to use a dozen sprinklers when considering antifreeze systems or "loops". For larger systems a dry pipe system should be used. 

 Preaction Sprinkler System: Similar to a dry pipe system with the exception that the special check valve, called a preaction valve is opened by a solenoid valve connected to a releasing panel and smoke or heat detectors. There are two basic types of preaction systems. A single interlock system admits water to sprinkler piping upon operation of the heat or smoke detection. A double interlock system allows water into the the piping system upon operation of both detection devices and a loss of piping air pressure. 

This type of system is used in sensitive areas such as computer rooms where an accidental discharge of water from a broken sprinkler or pipe would be harmful to the room contents.

Deluge Sprinkler System: Similar to a single interlock preaction fire sprinkler system with the exception that all the sprinkler heads are open. When the deluge valve operates by the electric detection water flows into the piping and out all sprinklers.

This type of system is used in areas where delivering a large amount of water is important to control fire such as stage areas and for water curtains around large openings for escalators.

Fire Sprinkler Animation: Click here to download a short slideshow demonstrating the operation of a sprinkler system. For more information and videos from the Home Fire Sprinkler Coalition click here.