Dry pipe system
The pipes in this system are filled with air under pressure and the water is held back by the control valve which is usually located outside the protected area. When the sprinkler head is activated, the valve releases the compressed air through the sprinkler head. Once all the air has been released, water fills the system.
You should note that this system has a slower reaction time. The good side with the system is that it releases large amount of water; therefore, fire is put off fast.
Another good thing is that you don’t have to worry about flooding in case there is leakage in the pipes. These systems are used in areas where the wet and alternate systems can’t be used.
These systems are usually filled with water for the summer period then when the season is over, they are drained down and filled with air for the winter period. These systems are ideal for underground car parks and other buildings that are not usually heated.
These are variations of the dry and wet pipe systems. These systems must be triggered twice before water is dispensed from the sprinkler head. The first trigger allows water into the pipes while the second trigger releases the water and pushes it to through the sprinkler in order to extinguish the fire.