Automatic drain valve for a compressed air system

Abstract

A drain valve for a compressed air system automatically discharges liquid separated from system air from a container in which the separated liquid is trapped when the trapped liquid activates the drain valve. A spring biases the valve element of the drain valve to an open position to drain the trapped liquid during system shut-down and is positioned in an outlet passage of the container so that the spring is accessible for replacement without dissassembly of the drain valve. A float in the container is responsive to the level of trapped liquid to open communication between the system pressure and a chamber on the upper side of a diaphragm type valve actuator to offset the system pressure in a chamber on the lower side of the valve actuator so that the spring and the pressure on the upper side of the valve actuator acting on the valve element moves the valve element to its open position for discharging the trapped liquid. The float includes a cup shaped member whose interior is in the form of an annular chamber with a continuous unbroken surface above its lower end so as to positively trap air therein which prevents excessive amounts of water from entering the float interior whereby water logging of the float is prevented. The valve element sealingly engages the diaphragm to seal the upper chamber from the lower chamber.

Dependencies are inferred from the claim text.