Abstract: A method and apparatus for calibrating the air flow in a respirator system is provided. The method provides for the establishment of control set points in a true calibration protocol through the simple triggering of the microprocessor of a controller. When the trigger is initiated, the microprocessor engages and provides the logic for the calibration cycle. The calibration cycle proceeds until a second trigger terminates the process and establishes the control set points. The calibration sequence of the method relies only on an initiation and termination trigger that is facilitated by components integral to the apparatus.