Process and apparatus for separation of a gas mixture with failsafe operation

A gas mixture is separated by compressing a starting mixture in a compressor system to a first pressure and feeding one or more product streams into the separation plant. In the event of failure or partial failure of the compressor system, an auxiliary stream with the same composition as either the product stream or starting mixture is compressed to the first pressure and fed into the plant. An Independent claim is included for apparatus for carrying out the above method with pipes (91, 92) for the auxiliary streams fitted with valves which are closed in normal operation but open if the compressor system fails.