Fuente: WIPO "tomato" There is described a nozzle unit (22) configured to direct a flow of gas towards a side of a web (3) of packaging material designed to produce sealed packages (2) containing a pourable product, wherein the nozzle unit (22) comprises a nozzle frame (26) and a nozzle member (27) having a nozzle surface (23) provided with openings through which supplying the flow of gas and the nozzle frame (26) and the nozzle member (27) are connectable to one another in a releasable manner. The nozzle unit (22) further comprises a locking and unlocking device (30) with at least a bracket (32) being elastically deformable metallic and provided with a rear portion (35) connected to a first surface (34) of the nozzle frame (26) and a front portion (36) configured to define a seat which accommodates an end portion of the nozzle member (27) .