A device for combustion chamber injector in a turbomachine, including: - a duct having at least: ∘ a first opening, and ∘ a second opening, - a system for blocking the duct, making it possible to regulate the passage of fluids in the duct, the blocking system including: ∘ a first head mounted on a first elastic module, said first head being capable of displacing to allow passage of fuel from the first opening toward the second opening only from a first pressure of the fuel, for passage of a supply of fuel, ∘ a second head mounted on a second elastic module, said second head being capable of displacing to allow transfer of air from the second opening toward the first opening from a second pressure, to allow passage of air from the second opening toward the first opening only from the second pressure of the air, for passage of purge air, the second pressure being greater than the first pressure, and - a stop allowing blockage of the displacement of the first head in the direction of displacement of the second head, characterized in that the first elastic module of the first head is fixed at one end of the second head, such that the displacement of the second head from the second pressure drives the displacement of the first head toward the stop. - a duct having at least: ∘ a first opening, and ∘ a second opening, ∘ a first opening, and ∘ a second opening, - a system for blocking the duct, making it possible to regulate the passage of fluids in the duct, the blocking system including: ∘ a first head mounted on a first elastic module, said first head being capable of displacing to allow passage of fuel from the first opening toward the second opening only from a first pressure of the fuel, for passage of a supply of fuel, ∘ a second head mounted on a second elastic module, said second head being capable of displacing to allow transfer of air from the second opening toward the first opening from a second pressure, to allow passage of air from the second opening toward the first opening only from the second pressure of the air, for passage of purge air, the second pressure being greater than the first pressure, and - a stop allowing blockage of the displacement of the first head in the direction of displacement of the second head, characterized in that ∘ a first head mounted on a first elastic module, said first head being capable of displacing to allow passage of fuel from the first opening toward the second opening only from a first pressure of the fuel, for passage of a supply of fuel, ∘ a second head mounted on a second elastic module, said second head being capable of displacing to allow transfer of air from the second opening toward the first opening from a second pressure, to allow passage of air from the second opening toward the first opening only from the second pressure of the air, for passage of purge air, the second pressure being greater than the first pressure, and - a stop allowing blockage of the displacement of the first head in the direction of displacement of the second head, characterized in that - a stop allowing blockage of the displacement of the first head in the direction of displacement of the second head, characterized in that