US Patent 7431033 Gas dispensing and recovery apparatus

A container (1) having a first compartment (3) and a second compartment (5) separated by a movable gas impermeable partition (7) is used for storing and dispensing a gas for use in a process and receiving and storing a gas recovered from the process. Fresh gas is dispensed (9) from the first compartment (3) for use in a process and recovered gas is fed (11) to the second compartment (5), whereby a volume of the second gas displaces a volume of the first gas by movement of the partition (7) to enlarge the second compartment (5) relative to the first compartment (3).