This is most commonly used system. This system utilizes a Deluge Valve Model ES0201 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 by either 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.