Abstract: A process gas controller, connected to a sources of purging and process gas, includes five valves and a pressure regulator between the process gas source and the equipment. Operating the valves provides process gas to the equipment and allows the controller to be vented of process gas and purged using the purging gas. A novel pneumatic valve controller, used to control the opening and closing of the valves, provides seven different valving combinations to supply process gas to the equipment, vent process gas and purge the system. The valve controller includes a program member having a number of passageways, each connected to one of the valves and to a program surface via program ports. A movable valve selection member overlies the program surface and includes an inlet passage coupled to a compressed source so that when the inlet passage becomes aligned with one of the various sets of program ports, compressed air is provided to the corresponding valves to actuate them.