Vortex tube assembly

A method of controlling separation of an inlet air flow into a nitrogen-enriched air (NEA) flow and an oxygen-enriched air (OEA) flow using a vortex tube assembly which comprises:

• a plenum chamber configured to receive the inlet air flow;
• a vortex chamber configured to centrifugally separate the inlet air flow into the NEA flow and the OEA flow;
• a swirl generator having an inlet passage which provides fluid communication between the plenum chamber and the vortex chamber;
• and
• a throttle pin positioned within the inlet passage, an outer surface of the throttle pin and an inner surface of the inlet passage co-operatively defining a flow path for air to enter the vortex chamber from the plenum chamber,
• wherein the throttle pin is selectively movable relative to the inlet passage between a restrictive position and a permissive position, said flow path being more constricted when the throttle pin is in the restrictive position than when the throttle pin is in the permissive position,
• wherein the method comprises:
• operating the vortex tube assembly with the throttle pin in one of said positions;
• then
• in response to a signal indicative of the flow path being obstructed, moving the throttle pin to the other of said positions and then back so as to clear an obstruction;
• and
• then continuing operation of the vortex tube assembly with the throttle pin in said one of said positions.