Tyco® Model AV-1-300 alarm valves are divided-seat ring, rubber-faced clapper, waterflow alarm valves that are intended for use in wet pipe 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, a bypass check valve, a main drain valve, and an alarm test valve. The bypass check valve reduces the possibility of false alarms by permitting slow and small transient increases in water supply pressure through the system without opening the waterway clapper.