Patent ID: 7854792

Claim:
An apparatus comprising: a chamber having an inner surface; a guide surface having a cylindrical shape with an interior face and terminating at an edge; a port formed from at least a portion of the inner surface proximate to the edge, the port connecting a gas inlet to the chamber; a first reservoir configured to deliver a first liquid to the interior face of the guide surface via a gap between the first reservoir and the guide surface, the first liquid delivered at a first flow rate; and a first circulation mechanism associated with the first reservoir and configured to impart a tangential velocity to the first liquid such that the first liquid swirls around the interior face of the guide surface in passing from the gap to the edge; wherein the shape of the guide surface and the first flow rate of the delivered first liquid flowing over the guide surface cause the first liquid to flow past the edge to the inner surface, such that the first liquid forms a liquid membrane that prevents a flow of gas through the port under a first pressure difference between gas pressures in the chamber and the gas inlet.