Pre-Action Systems

Pre-Action Fire Sprinkler systems are a special type of system installed to stop the accidental discharge of water in high value areas of a building.  Installations include computer rooms, large Freezers, Libraries, Museums, Archives or any other high value area where the accidental discharge of water would be costly!

In a standard wet pipe fire sprinkler system the water is inside the piping at all times supplying the fire sprinkler heads.  When a head fuses (thermal link melts or breaks) or is mechanically damaged or a pipe breaks, water is discharged.

 

 

A pre-action system is installed in the same manner except the piping supplying the fire sprinkler heads is dry.  A special pre-action check valve holds back the water until a separate detection system tied to the pre-action check valve senses there is a fire.  Once the detection system is activated, it will open the pre-action check valve filling the system with water. Water still will not discharge until a fire sprinkler head actually fuses allowing water to flow to the fire.  There are several types of detection systems that can be used to trip the pre-action valve; the installation contractor will recommend the best type for the application.  Pre-action system piping will also be pressurized with air to monitor the empty piping for leaks or breakage.  Loss of air will notify the alarm panel there is a problem.  All the extra components needed to trip a pre-action valve must be tested at required intervals to verify the system will work properly in the event of a fire.

 

Pre-action systems are required to be tested annually.