The system is equipped with a supplemental detection system whose function varies depending on the type of preaction system. The types of detection systems most commonly used are pneumatic or electric actuation. Preaction systems are used where it is important to prevent an accidental discharge of water, when an alarm is desired in advance of sprinkler operation, or when it is desired to reduce the water delivery delay inherent in a dry pipe system.
Inbal Preaction Systems are available in the following
Non-Interlock - Utilizes a dry pipe valve and a supplemental pneumatic or electric detection system. The valve may be opened either by operation of a sprinkler in the sprinkler piping or by operation of the detection system.
Single Interlock - Utilizes a deluge valve and a supervisory air pressure system. Loss of air in the sprinkler piping system due to damaged piping or broken sprinklers will only operate the alarm systems and will not cause water to flow through the deluge valve and into the system. The valve will open only if the electric or pneumatic detection system operated.
Double Interlock - Utilizes an automatic water control valve, an electric or pneumatic detection system, and a pressurized (air or gas) sprinkler piping system. Only operation of both detection and sprinkler piping systems will allow water to enter the sprinkler system and be discharged through the fused sprinkler(s). The valve is FM approved to 300 psi (21 bar) in sizes 3", 4", 6", and 8" (80, 100, 150, & 200 mm) as a valve for Refrigerated Areas.