Single interlocked pre-primed preaction systems are commonly used where the sprinkler system piping and/or sprinkler may be subject to damage or systems must be wet type. The most common applications are in system applications where it is important to use wet pipe systems, such as ceiling only ESFR systems, and limit accidental water discharge due to damaged sprinklers or piping. Viking supervised, single interlocked preaction pre-primed systems utilize a Viking Deluge Valve and a hydraulically pressurized automatic sprinkler system. The system piping is hydraulically pressurized with an approved fire suppression solution for supervisory purposes and pre-prime requirements of NFPA. If acceptable by the authority having jurisdiction, this feature allows the system to be applied as a wet system and serve to prevent undetected leaks. If the system piping or a sprinkler is damaged, supervisory pressure is reduced and a supervisory alarm is activated. Electrically controlled preaction systems require an electric Solenoid Valve controlled by an approved System Control Panel with compatible detection system that meets the application. Detection system must actuate prior to or at the same time as sprinklers. In fire conditions, when the detection system operates, System Control Panel energizes Solenoid valve open, causing Deluge Valve to open. The riser piping fills with water, pressurizing already existing solution. If any sprinklers have opened, water or solution will flow from the system. If sprinklers have not opened, pressurized water will be in the sprinkler system piping when the sprinkler operates. A sprinkler head must open before solution flows from the system.