A gas distribution nozzle comprising a base and an internal gas expansion system (20, 21, 22), wherein: - the internal gas expansion system (20, 21, 22) comprises a release valve engaging with a valve seat at which a release port opens, and - the base comprises a high pressure gas inlet through which passes a highpressure gas passage fluidly connecting said high pressure gas inlet to the release port of the valve seat, said valve further comprising: - a cap surmounting the base and having a low-pressure gas passage opening at a gas outlet, said cap being movable relative to the base between at least: -- a closed position wherein the cap pushes back the release valve against the valve seat so as to completely block the release port and prevent any gas release, and -- a release position wherein the cap allows the release valve to be a given distance away from the valve seat so as to free the release port and to allow a gas pressure reduction between the release valve and the valve seat, and a flow of low pressure gas in the low-pressure gas passage of the cap, - at least one elastic element which elastically pushes the cap in a direction tending to move it away from the base to move it from the closed position to the release position, - a locking device (11, 14) engaging with the base and the cap for holding the cap in the closed position, the locking device (11, 14) comprising at least one locking pin and a gripper can be grasped manually by a user, characterised in that the locking pin of the locking device (11, 14) passes through a passage of the cap and engages with a housing of the base for keeping the cap in the closed position. - the internal gas expansion system (20, 21, 22) comprises a release valve engaging with a valve seat at which a release port opens, and - the base comprises a high pressure gas inlet through which passes a highpressure gas passage fluidly connecting said high pressure gas inlet to the release port of the valve seat, - a cap surmounting the base and having a low-pressure gas passage opening at a gas outlet, said cap being movable relative to the base between at least: -- a closed position wherein the cap pushes back the release valve against the valve seat so as to completely block the release port and prevent any gas release, and -- a release position wherein the cap allows the release valve to be a given distance away from the valve seat so as to free the release port and to allow a gas pressure reduction between the release valve and the valve seat, and a flow of low pressure gas in the low-pressure gas passage of the cap, -- a closed position wherein the cap pushes back the release valve against the valve seat so as to completely block the release port and prevent any gas release, and -- a release position wherein the cap allows the release valve to be a given distance away from the valve seat so as to free the release port and to allow a gas pressure reduction between the release valve and the valve seat, and a flow of low pressure gas in the low-pressure gas passage of the cap, - at least one elastic element which elastically pushes the cap in a direction tending to move it away from the base to move it from the closed position to the release position, - a locking device (11, 14) engaging with the base and the cap for holding the cap in the closed position, the locking device (11, 14) comprising at least one locking pin and a gripper can be grasped manually by a user,