Double Interlock Preaction System with 502 Deluge Valve Electric / Pneumatic Release

The Double Interlock Preaction System with Electric/Pneumatic Release is generally used to protect water sensitive areas such as
computer rooms, storage areas, refrigerated areas etc., to avoid water damage due to inadvertent flooding of the sprinkler system
piping.

In normal condition, preaction system does not contain water in the sprinkler piping. The sprinkler piping contains air pressure for the
purpose of supervising its leak tightness.

This is most commonly used system. This system utilizes a Deluge Valve Fig.502 and Riser Check Valve Model CH. The Riser Check Valve isolates the Deluge Valve from the system air pressure. Riser Check Valve provides an air check so that the system can be
automatically pressurized with a supervisory air or nitrogen pressure of 42 PSI (2.94 Bar). A supervisory low pressure alarm switch can be
set at 20 PSI (1.40 Bar), on decreasing pressure, to indicate whether there are any abnormal leaks in the sprinkler system piping. Loss
of air pressure from the system due to accidental leakage will not cause Deluge Valve to open.

The releasing trim for Deluge Valve utilizes a Solenoid Valve and a Dry Pilot Actuator in a series configuration. The system air pressure
holds the Dry Pilot Actuator closed, whereas the Solenoid Valve remains closed until it is electrically energized by a Deluge Valve
Releasing Panel (automatic control unit). The Releasing Panel is operated either by a fire detection device or manual electric
pull station. In order for the Double Interlock Pre-Action System to automatically actuate, two independent events must occur.
The Deluge Valve Releasing Panel must operate and open the Solenoid Valve upon automatic operation of the electric fire
detection initiating circuit and the sprinkler system piping must lose air pressure due to operation of one or more sprinklers. The Double
Interlock Pre-Action System will automatically actuate only when both the Dry Pilot Actuator and the Solenoid Valve are open at
the same time. Unintended opening of just the Dry Pilot Actuator or the Solenoid Valve will only cause an alarm and not actuate the
system or flood the sprinkler system piping.