The TYCO Model AV-1-300 Alarm Valves DN65, DN100, DN150, and DN200 (European Conformity) are divided-seat ring, rubber-faced clapper, waterflow alarm valves that are intended for use in wet pipe (automatic sprinkler) fire protection systems. They are designed to automatically actuate electric and/or hydraulic alarms when there is a steady flow of water into the system that is equivalent to the discharge rate of one or more sprinklers.An optional Model RC-1 Retard Chamber is required for installations subject to variable pressures. It is used to help prevent false alarms associated with pressure variations in public water supplies.The Model AV-1-300 Alarm Check Valve Trim includes pressure gauges to monitor system pressure conditions