Rotors for use in caustic environments

A medical device comprising:

• a respiratory therapy device configured for Assist/Control Ventilation, Intermittent Mandatory Ventilation, Pressure Support Ventilation, Continuous Positive Airway Pressure (CPAP) treatment, Non-Invasive Positive Pressure Ventilation (NIPPV), or Variable Positive Airway Pressure (VPAP) and to deliver high velocity respiratory fluid to a patient, the respiratory device comprising:
• rotatable impeller assembly for pumping caustic fluid byproducts in a medical device, the impeller assembly having a central axis, comprising:
• a rotor comprising a rotor cup;
• an impeller having a rotor contacting surface and impeller blades, wherein the impeller comprises holes that extend through the impeller assembly;
• a single-piece magnetic ring seated within the rotor cup, the magnetic ring comprising a first contact surface that is configured to mate with an inner surface of the rotor cup, and a second contact surface that is configured to mate with the rotor contacting surface of the impeller, the magnetic ring thereby being locked in position by the inner surface of the rotor cup and the rotor contacting surface of the impeller so as to prevent any independent rotation of the magnetic ring relative to the rotor cup and the impeller while automatically balancing the rotor,
• the inner surface of the rotor cup comprising a continuous ridge comprising an O-ring that mates with a corresponding groove formed in the first contact surface of the magnetic ring, thereby locking the magnetic ring in a fixed position relative to the rotor cup;
• wherein the rotor contacting surface of the impeller is attached to the rotor cup to hermetically seal the magnetic ring within the impeller assembly;
• and
• a single ball bearing in line with the central axis, supporting the impeller.