Apparatus for conveying gases to and from a chamber

1. An apparatus for conveying gases to and from a chamber comprising:

a chamber having a chamber inlet and a chamber outlet;

a first inlet for receiving a first gas stream;

a second inlet for receiving a second gas stream;

a first outlet for outputting the first gas stream to a first vacuum pump;

a second outlet for outputting the second gas stream to a second vacuum pump;

a conduit network for connecting the first inlet to the first outlet and for connecting the second inlet to the second outlet such that, for each gas stream, first and second flow paths are defined between its respective inlet and outlet, the first flow path passing through the chamber inlet and the chamber outlet, and the second flow path by-passing the chamber;

means for routing the gas streams through the network such that when one gas stream flows along its first flow path, the other gas stream flows along its second flow path; and

wherein part of the second flow path for the first gas stream is common to the second flow path for the second gas stream.

2. An apparatus for conveying gases to and from a chamber comprising:

a chamber having a chamber inlet and a chamber outlet;

a first inlet for receiving a first gas stream;

a second inlet for receiving a second gas stream;

a first outlet for outputting the first gas stream to a first vacuum pump;

a second outlet for outputting the second gas stream to a second vacuum pump;

a conduit network for connecting the first inlet to the first outlet and for connecting the second inlet to the second outlet such that, for each gas stream, first and second flow paths are defined between its respective inlet and outlet, the first flow path passing through the chamber inlet and the chamber outlet, and the second flow path by-passing the chamber;

means for routing the gas streams through the network such that when one gas stream flows along its first flow path, the other gas stream flows along its second flow path;

a third inlet for receiving a third gas stream, and wherein the conduit network connects the third inlet to the first outlet such that, for the third gas stream, a first flow path is defined between the third inlet and the first outlet which passes through the chamber inlet and the chamber outlet; and

wherein the conduit network connects the third inlet to the first outlet such that, for the third gas stream, a second flow path is defined between the third inlet and the first outlet which by-passes the chamber, the routing means being configured to route the gas streams through the network such that when one of the gas streams flows along its first flow path, the other gas streams flows along their second flow paths.

3. The apparatus according to claim 2 wherein the routing means comprises a third valve system located within the conduit network, and means for controlling the third valve system to route the third gas stream from the third inlet to a selected one of its first and second flow paths.

4. An apparatus for conveying gases to and from a chamber comprising:

a first inlet for receiving a first gas stream;

a second inlet for receiving a second gas stream;

a first outlet for outputting the first gas stream;

a second outlet for outputting the second gas stream;

a first chamber port connectable to an inlet of the chamber;

a second chamber port connectable to an outlet of the chamber;

a conduit network for connecting the first inlet to the first outlet and for connecting the second inlet to the second outlet such that, for each gas stream, first and second flow paths are defined between its respective inlet and outlet, the first flow path passing through the chamber ports, and the second flow path by-passing the chamber ports;

means for routing the gas streams through the network such that when one gas stream flows alone its first flow path, the other gas stream flows along its second flow path; and

wherein part of the second flow path for the first gas stream is common to the second flow path for the second gas stream.

5. An apparatus for conveying gases to and from a chamber comprising:

a first inlet for receiving a first gas stream;

a second inlet for receiving a second gas stream;

a first outlet for outputting the first gas stream;

a second outlet for outputting the second gas stream;

a first chamber port connectable to an inlet of the chamber;

a second chamber port connectable to an outlet of the chamber;

a conduit network for connecting the first inlet to the first outlet and for connecting the second inlet to the second outlet such that, for each gas stream, first and second flow paths are defined between its respective inlet and outlet, the first flow oath passing through the chamber ports, and the second flow path by-passing the chamber ports;

means for routing the gas streams through the network such that when one gas stream flows alone its first flow path, the other gas stream flows along its second flow path;

a third inlet for receiving a third gas stream, and wherein the conduit network connects the third inlet to the first outlet such that, for the third gas stream, a first flow path is defined between the third inlet and the first outlet which passes through the first and second chamber ports; and

wherein the conduit network connects the third inlet to the first outlet such that, for the third gas stream, a second flow path is defined between the third inlet and the first outlet which by-passes the chamber ports, the routing means being configured to route the gas streams through the network such that when one of the gas streams flows along its first flow path, the other gas streams flows along their second flow paths.

6. The apparatus according to claim 5 wherein the routing means comprises a third valve system located within the conduit network, and means for controlling the third valve system to route the third gas stream from the third inlet to a selected one of its first and second flow paths.