Pre-action Sprinklers System

The Pre-action sprinkler systems are used to protect areas where water damage from damaged sprinklers or piping needs to be avoided. These are a middle ground between dry and wet fire protection systems. The major difference between a deluge suppression system and a pre-action system is that pre-action systems are filled with compressed air. The sprinkler heads remain closed until needed, and a pre-action valve holds back the water. It is a hybrid dry/wet system as it is a dry system until it is activated at which point it becomes a wet system.

Pre-action fire sprinkler systems require two steps to discharge the agent. When the system first detects heat or fire the pre-action valve opens. Next, the pipes are flooded with water, dry chemicals, inert gases, or foam. After it's filled, the specific sprinkler head must detect heat or fire to open. Then, the system will work to extinguish the fire in the immediate area.