Abstract: A self-closing connector in accordance with the invention comprises at least one duct, at least one end orifice, and a sliding valve plate for closing said orifice, the connector is essentially characterized by the fact that said orifice (11, 28, 29, 32) is delimited by at least two lines of sealing (17, 26) disposed on respective closed curves and each belonging to a respective one of two cylindrical surfaces having generator lines extending in the same direction, and in that the sliding valve plate 12 has at least two sealing (12) surfaces belonging to said cylindrical surfaces respectively, with the projection of the section areas of the valve plate which co-operate with respective one of said two sealing lines on a plane P perpendicular to said generator lines having values equal to S'.sub.1 and S'.sub.2. Said section areas are chosen to be equal. This enables the effects of externally-applied pressure to cancel.