Abstract: A gas delivery system, having a gas identification, by which a gas supplied to the gas delivery system is identified, a blender, blending oxygen and the gas to provide a gas mixture with an oxygen flow rate set up by an operator, and at least one flow sensor, to measure a flow rate of the gas mixture. The blender is driven by an actuator motor to various blender positions with the blender positions being calibrated based on the specific heat ratio and the gas constant of the gas. The flow sensor can be installed at the inspiratory circuit, the proximal circuit and the expiratory circuit of the gas delivery system. The flow sensor output is corrected based on the actual conditions, including the temperature, pressure and humidity, and characteristics of the gas mixture.

Abstract: Roots-type blowers with helical cycloidal rotors exhibit variation in leakback flow with angular position intrinsic to these rotor geometries. Calibration of individual blowers using a combination of high-resolution alignment and enhanced detection of residual noise phenomena permits noise in as-produced blowers to be significantly attenuated. Intrinsic lower limits of noise induced by leakback variation are associated with manufacturing tolerances, necessary clearances, and particular geometric considerations. Gross alignment errors (excluding contact between rotors) produce a characteristic noise pulse rate that is three times the shaft rate. Proper alignment suppresses this and reveals a pulse sequence at double this rate and at about half of the amplitude of faulty alignment. The novel process explains the error mechanisms and defines repeatable calibration methods for a mass-production environment, introducing appropriate gauges and methods for the task.

Abstract: The present invention is a catheter having a tube and including mechanisms that provide precision control over insertion and retraction of the catheter tube. The catheter is particularly adapted for introduction into the pulmonary system. The catheter includes an insertion depth control mechanism that acts as a stop and provides a tactile indication to the person inserting the catheter tube that a predetermined position has been reached. The catheter also includes an anti-bunching mechanism to prevent bunching of a protective sleeve disposed around the catheter tube, thereby reducing interference from the sleeve during insertion of the catheter tube.