Device for feeding a fluid to a container comprising: - at least one supplying line for supplying said fluid; - at least one inlet end for the inlet of the fluid into said at least one supplying line, said at least one inlet end being designed to be put in fluid communication with a fluid source; - at least one dispensing end for dispensing the fluid into said container; - at least one opening/closing valve member intercepting said at least one supplying line and which is movable between a closing position, wherein it obstructs the fluid supplying between said at least one inlet end and said at least one dispensing end, and at least one opening position, wherein it allows the fluid supplying between said at least one inlet end and said at least one dispensing end; further comprising: - at least one pressure adjusting member intercepting said at least one supplying line and designed to receive in inlet said fluid at an inlet pressure and to supply it at an outlet pressure, said pressure adjusting member having a variable outlet pressure; - storing or locking/unlocking means movable between a condition of setting or fixing said outlet pressure exiting from said pressure adjusting member and a resting condition, and in that said locking/unlocking means comprise at least one control valve arranged to intercept said supplying line or a branch line of said supplying line as well as at least one fluid connecting conduit between said control valve and said pressure adjusting member, said control valve being movable between a position wherein it allows the fluid flowing from said supplying line or said branch line to said connecting conduit and a position wherein it closes said connecting conduit, characterised in that when said connecting conduit is closed, the outlet pressure of the pressure adjusting member is fixed. - at least one supplying line for supplying said fluid; - at least one inlet end for the inlet of the fluid into said at least one supplying line, said at least one inlet end being designed to be put in fluid communication with a fluid source; - at least one dispensing end for dispensing the fluid into said container; - at least one opening/closing valve member intercepting said at least one supplying line and which is movable between a closing position, wherein it obstructs the fluid supplying between said at least one inlet end and said at least one dispensing end, and at least one opening position, wherein it allows the fluid supplying between said at least one inlet end and said at least one dispensing end; further comprising: - at least one pressure adjusting member intercepting said at least one supplying line and designed to receive in inlet said fluid at an inlet pressure and to supply it at an outlet pressure, said pressure adjusting member having a variable outlet pressure; - storing or locking/unlocking means movable between a condition of setting or fixing said outlet pressure exiting from said pressure adjusting member and a resting condition, and in that said locking/unlocking means comprise at least one control valve arranged to intercept said supplying line or a branch line of said supplying line as well as at least one fluid connecting conduit between said control valve and said pressure adjusting member, said control valve being movable between a position wherein it allows the fluid flowing from said supplying line or said branch line to said connecting conduit and a position wherein it closes said connecting conduit, characterised in that when said connecting conduit is closed, the outlet pressure of the pressure adjusting member is fixed. - at least one pressure adjusting member intercepting said at least one supplying line and designed to receive in inlet said fluid at an inlet pressure and to supply it at an outlet pressure, said pressure adjusting member having a variable outlet pressure; - storing or locking/unlocking means movable between a condition of setting or fixing said outlet pressure exiting from said pressure adjusting member and a resting condition,