Viking VXD Double-Interlocked Preaction Systems use a Viking Model VXD Deluge Valve that is controlled by a pneumatic actuator. The actuator is normally held closed by the sprinkler system's air/nitrogen that is maintained by a normallyclosed electric solenoid valve. In order for the deluge valve to open and fill the system with water, the releasing panel with electric detection system must activate and the air/nitrogen must be relieved from the system. If the electric detection system (alone) operates due to fire, damage, or malfunction, 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, operation of both the detection system and a sprinkler is required before the deluge valve will open allowing water to enter the system piping.

Electric/Pneumatic double interlocked preaction systems are commonly used as refrigerated area systems, where flooding of the pipe can have serious consequences, and where it is important to control accidental water discharge due to damaged sprinkler piping. Care should be taken since double interlocked preaction systems may not produce flow from opened sprinklers as quickly as single- or non-interlocked preaction systems. Activation of the detection system alone, or operation of a sprinkler alone, will sound an alarm but will NOT cause the system to fill with water.

Pre-Trimmed Riser packages come completely assembled and ready to install. These packages include the Model VXD deluge valve with trim, a riser check valve, additional components as shown below, and come with galvanized pipe and groove/groove connections only.
The Pre-Trimmed Riser packages include the following components: Model VXD valve 
• Riser check valve
• completely assembled trim
• electric release solenoid
• pneumatic actuator
• water supply control valve
• pressure gauges for air and water
• grooved couplings
• water flow and air supervisory pressure switches
• complete drain manifold with hoses and drain cup

Each configuration can be ordered with a monitored or non-monitored release solenoid. The monitored solenoid is a new option, which offers an NFPA 13 solenoid monitoring-compliant solution.