Compressed air processing device for vehicle air system

The device has a pressure regulator, an air dryer (6) and a multi-circuit protection valve (9) with at least one magnetic valve (35) with an overflow valve (18) per circuit with limited reverse flow, a movable wall (20) separating an inlet chamber from a rear chamber and a working surface (33) acted upon by the magnetic valve on the same or opposite side of the wall as the inlet chamber.