Abstract: The conduit sections of a multiple duct conduit system each include a coupling assembly 15 mounted at one end of each conduit section 10, with the coupling assembly including an outer cylindrical coupling 24 and an inner coupling 25. The inner coupling includes an inner receptacle 45 having a support plate 40 with sockets 44 and 45 mounted to both sides of the support plate in alignment with openings in the support plate. O-rings 55 are seated in annular grooves 54 of the passageways formed by the sockets, and internal flanges 48 project inwardly of each passageway. When the conduit sections are connected in end-to-end relationship, the protruding inner ducts 12 of one conduit section 10B are moved into the coupling assembly 15 until the inner ducts 12B are moved into the inner coupling assembly 25, whereupon the relatively small openings 45 of the O-rings 55 are stretched so as to permit passage therethrough of the inner ducts 12. This forms a seal about the inner ducts.