US Patent 9868001 Respirator flow control apparatus and method

An air flow control system for a respirator (10) is described which includes a shell that defines a breathable air zone for a user (18) wearing the respirator (10), an air delivery conduit (27) within the shell of the respirator, and a valve member (557) moveable relative to the air delivery conduit and within the shell to vary the air flow through the air delivery conduit. The air flow control system also includes an outer device (46) outside of the shell of the respirator that is rotatable by a user (18) of the respirator while wearing the respirator to control movement of the valve member.