Also see: How do Spinklers work?
Wet Pipes
These are the most common systems and are used in buildings where there is no risk of freezing. They are fast to react because water is always in the pipes above the sprinkler heads.
Wet systems are required for multi-storey or high rise buildings and for life safety.
Alternate
As the name suggests Alternate systems can have the pipes full of water for the summer and be drained down and filled with air (under pressure) for the winter. This is important for buildings that are not heated.
Dry Pipe
The pipes are filled with air under pressure at all times and the water is held back by the contol valve. When a sprinkler head opens the drop in air pressure opens the valve and water flows into the pipework and on to the fire. Dry pipe systems are used where wet or alternate systems cannot be used.
Pre-Action
Like dry pipe systems the pipes are filled with air but the water is only let into the pipes when the detector operates (eg smoke detectors etc). Pre-action systems are used where it is not acceptable to have the pipes full of water unless there is a fire.
Deluge and Re-cycling Installations
These are not strictly sprinkler systems and are only used in special cases for inustrial risks.
with courtesy of BAFSA
“In the ten years we have been dealing with Fire Defence we have found them very responsive to our needs and reasonably priced. It is reassuring to know that our company is covered by a good system, which is properly maintained by Fire Defence.”
R V Boyle - Managing Director - Buckleigh Linen Services