A device for a turbomachine chamber injector, including a conduit having at least a first opening, and a second opening (4), a blocking system for blocking the conduit, making it possible to regulate the passage of fluids into the conduit, the blocking system being configured to allow fuel to flow from the first opening to the second opening only from a first pressure of the fuel, for the passage of a supply of fuel, and allow air to flow from the second opening to the first opening only from a second pressure of the air, for the passage of purge air, the second pressure being greater than the first pressure.