The alarm check valve is a water flow alarm device designed for vertical installation in the main supply to a wet pipe sprinkler system. Alarm Check Valve is one type of check valve that prevents reverse flow from sprinkler piping by trapping pressurized water above the clapper. Retarding Chamber is used with Alarm Valve Trim when variable pressure is anticipated in the system. It is a holding tank to prevent activation of the Sprinkler Alarm during water pressure surge, but permits the activation of alarm on sustained flow. Mounting Type: Vertical. Sprinkler Alarm is a hydraulically driven mechanical bell. It does sound a continuous alarm when the sprinkler system operates. Mounting type Type-A & Type-B