The invention relates to a gas dispensing unit comprising: a main gas line (11) including an inlet (14a) and an outlet (14b) for the gas； a first auxiliary gas supply line (21) fluidly connected, via a downstream end (21a), to the main fluid line (11) and comprising at least one controllable valve (22) capable of controlling the passage of gas from the auxiliary line (21) to the main line (11)； a non-return gas device (15) disposed on the main fluid line (11)； a first pressure sensor (12) comprising a gas pressure port fluidly connected to the main line (11) between the inlet (14a) and the non-return means (15), and/or a second pressure sensor (13) comprising a gas pressure port fluidly connected to the main line (11) between the non-return means (15) and the outlet (14b)； and a control system (5) connected to the first pressure sensor (12) and/or the second pressure sensor (13), which controls said at least one controllable valve (22) in response to at least one pressure measurement taken by at least one of the sensors (12, 13).
