Patent ID: 6155289
Filing Date: 2000-12-05
Classification: G05D,Y10T

Abstract:
A backflow control apparatus for use with a sub-atmospheric gas source and a chamber, for preventing backflow into the sub-atmospheric gas source, the apparatus comprising:a) a gas line fluidly coupling the sub-atmospheric gas source and the chamber;b) a valve in fluid communication with the sub-atmospheric gas source, for blocking fluid communication between the gas source and said gas line upon receipt of a first signal;c) a flow restrictor in fluid communication with said gas line and positioned between said valve and the chamber;d) a first pressure transducer in fluid communication with said gas line between said valve and said flow restrictor, capable of generating a second signal representative of the pressure in said gas line between said valve an said flow restrictor;e) a second pressure transducer in fluid communication with said gas line between said first pressure transducer and the chamber, capable of generating a third signal representative of the pressure in said gas line between said restrictor and the chamber; andf) a valve controller unit connected to said first pressure transducer, said second pressure transducer and said valve, said controller capable of generating said first signal in response to said second and third signals.