Method and device for decomposing a gaseous mixture with emergency operation.

Method of dissociating a gas mixture in a separation installation, in which a feed gas (18) is compressed in a compressor system (6, 16) to a first pressure and then the gas at least partially introduced into the separation plant, which is generated during normal operation at least a first product stream (91, 92), characterized in that, in the event of total failure or partial failure of the compressor system (6, 16), a first partial stream which has approximately the composition of the first product stream or approximately the composition of the feed gas, is led (78, 89) to at least approximately the first pressure and returned to the separation plant.