NON-INTERLOCK PREACTION (Type B)

A Non-Interlock Preaction System is a specialized fire protection system that combines features of both dry pipe and preaction sprinkler systems. Its design intent is to ensure reliable operation under a range of conditions, particularly where fire detection redundancy is desired. In this arrangement, the preaction valve can open by either of two initiating events—activation of the electric detection system or the opening of one or more fire sprinklers due to heat. When the detection system senses fire, the valve opens and fills the sprinkler piping with water, similar to a single-interlock preaction system. Water will not be discharged from the sprinklers until a sprinkler then operates. Unlike standard dry pipe systems, this “”pre-activates” the system piping with water, reducing the water delivery delay times of dry pipe systems. However, if the detection system fails to operate, the system will still function as a dry pipe system, allowing water flow upon sprinkler activation alone. This dual-mode capability provides enhanced reliability, ensuring that water delivery to the fire area is not dependent solely on detection electronics while still offering protection against accidental water discharge under normal conditions. This system type is also referred to as a Type “B” Preaction system in accordance with EN 12845.