Vacuum pumping system and method

A vacuum pumping system and method for evacuating a vacuum system such as a wafer transfer station comprising a smaller load lock vacuum chamber 30 operable to cycle between a predetermined pressure below atmospheric and atmospheric pressure, and a larger wafer transfer vacuum chamber 40 maintained at or close to the predetermined pressure. The vacuum pumping system comprises first and second vacuum pumps 10, 20, a valve system V1-V5 to selectively connect and isolate the first and second vacuum pumps with the smaller and larger vacuum chambers and control circuitry. The control circuitry is configured to, and the method comprises, in response to determining that a pressure within the smaller vacuum chamber is to fall to the predetermined pressure, control the valve system such that the first and second pumps are isolated from the larger vacuum chamber and in fluid communication with the smaller vacuum chamber, both contributing to evacuating the smaller vacuum chamber. When the smaller vacuum chamber is at the predetermined pressure the second vacuum pump is isolated from the smaller vacuum chamber and pumps the larger vacuum chamber.