Viking FSX-A Double Interlocked Preaction Systems with Electric/Pneu-Lectric release utilize a Viking deluge valve, pneumatic supervision of the automatic sprinkler system via pressurized air/nitrogen, and an electric detection system. The deluge valve release trim utilizes a normally closed electric solenoid valve controlled by an approved release control panel with two initiating circuits configured for “cross-zoned” operation. One initiating circuit is connected to the electric detection system; the other to a “low-air” supervisory switch.

BOTH the electric detection system must activate AND air/nitrogen pressure must be relieved from the sprinkler system before the deluge valve will open to fill the sprinkler system with water. If the electric detection system (alone) operates, an alarm will activate but the deluge valve will NOT open. If the sprinkler piping is damaged or a sprinkler is broken or fused, but the detection system has not activated, an alarm will activate, but the deluge valve will NOT open.

In fire conditions, after both the detection system and a sprinkler operate, the deluge valve opens, allowing water to enter the system.

Electric/pneu-lectric double interlocked preaction systems are commonly used as refrigerated area systems. They are also commonly used where flooding of the sprinkler system piping can have serious consequences and where it is important to control accidental water discharge due to damaged sprinkler piping.