The Automatic Air Maintenance Device is a UL Listed and FM Approved assembly of valves, nipples, fittings, and actuators to automatically control the air pressure in the piping of dry pipe sprinkler systems, preaction sprinkler systems, or dry pilot actuated deluge systems. The Air Maintenance Device is designed to automatically feed air into the system piping at the required volume and pressure from an air source. General Air Products UL/FM Approved Air Maintenance Devices are designed to control the amount of air fed into the dry pipe system so that the volume of air available does not effect the ability of the water to move through the piping system while maintaining the system pressure. Model AMD-2 Air Maintenance Device is used for automatic operation in conjunction with a dedicated fire protection air compressor that does not have a pressure switch installed, such as our L Series base mounted lubricated units.