Type F Double Interlock Preaction Systems are designed for water-sensitive areas that require the maximum protection from inadvertent water flow into the sprinkler system piping. A refrigerated area is an example of this type of water sensitive environment
The double interlock trim package includes a normally-closed solenoid valve (175 psi (12,1 bar) or 250 psi (17,2 bar) rated) and the Model LP Dry Valve Actuator arranged in series as releasing devices. The sprinkler system is pressurized with air or nitrogen that keeps the Model LP Dry Valve Actuator closed. To flow water into a Type F Double Interlock Preaction System, two events must take place. The Model LP Dry Valve Actuator must be opened by a venting of the sprinkler system’s air pressure, and the normally - closed solenoid valve must be energized open by properly activating the releasing/control panel, i.e. when a fire detection device or manual emergency station is operated.
In the event that the system piping is ruptured, or a sprinkler head is accidentally opened, the Model LP Dry Valve Actuator will open and a low system air pressure alarm will sound. The Model DDX Deluge Valve, however, will not be released to flow water since the solenoid valve still remains closed. The same end result would occur if a fire detection device were falsely operated. The control panel will activate an alarm, however again, the Model DDX Deluge Valve will not flow water due to the fact that the Model LP Dry Valve Actuator remains closed. This requirement for both a detector and a sprinkler to operate before the Model DDX Deluge Valve releases water into the preaction system assures maximum protection against inadvertent water flow before a sprinkler is open. Double interlock preaction systems are primarily used to protect refrigerated areas where accidental water release before a sprinkler is opened can cause ice blockage, resulting in an inoperative sprinkler system and substantial property damage.
At the heart of Rapidrop’s Type F Double Interlock Preaction System is the Model DDX Deluge Valve. This Deluge Valve is a hydraulically operated, straight-trough-design, differential type valve. System maintenance is simplified since priming water is not required and the Deluge Valve can be reset extemallywithoutcoverremovaLThis is accomplished by pushing in and turning the external reset knob at the rear of the Deluge Valve. This feature provides a significant system restoration time advantage The Rapidrop Type F Double Interlock Preaction System trim set provides all of the necessary equipment for connections to the Model DDX Deluge Valve’s pushrod chamber inlet and outlet ports, the 1¼” (50mm) main drain, alarm devices, air supply, water supply, and required pressure gauges. This trim set is available in individual parts, in time-saving, segmentally assembled kit forms, or fully assembled to the Model DDX Deluge Valve (with or without a control valve). All sizes Type F Double Interlock Preaction System trim sets may be equipped with the optional Rapidrop Model B1 Accelerator, trim kit PIN 6516000003. This device acts as an exhauster which will hasten operation of the Model LP Dry Valve Actuator and minimize the water delivery time for the entire system.