The present invention relates to a device for maintaining, in a filling machine, a gas flow barrier between two volumes of a channel, said channel being adapted for transportation of packages in a length direction thereof, and said volumes comprising a first volume having a first degree of sterilization, and a second volume having a second degree of sterilization. Further, the first volume comprises gas injection means, the second volume comprises gas evacuation means, and the first and second volume meet in an interface area extending in a length direction of the channel. The two volumes meet in venturi zone, a portion of the channel having a reduced cross section. The present invention also relates to a method for maintaining a gas flow barrier in a filling machine.
