Device comprising a demand valve (1) for delivering breathable gas to a diver and a fluidic connector (2, 5) that can be selectively connected to the demand valve (1), the demand valve (1) comprising a breathable gas supply inlet (3, 13), characterized in that the demand valve (1) and / or the fluidic connector (2, 5) comprise a blocking device (6, 7, 8, 9; 6, 7, 66, 50) for selectively blocking the connector (2, 5) on the demand valve (1) when the connector (2, 5) is fastened to the demand valve (1) via the catching members (103, 12; 213, 5), the blocking device (6, 7, 8, 9; 7, 66, 50) being selectively moveable and / or deformable between a first configuration of blocking relative movement between the demand valve (1) and the connector (2, 5), and a second configuration of unblocking, allowing relative movement between the demand valve (1) and the connector (2, 5).