Abstract: The invention refers to a coupling device for fluid conduits suitable for cases in which uncontrolled tamperings of the coupling ought to be avoided. The device includes a head provided with a coupling thread for a sleeve which incorporates a straight-profiled dentation, while between the sleeve and the head there is a complementary ring provided with another dentation. The dentations are oriented to permit the sleeve to turn in a tightening direction and to prevent it from turning in the opposite direction at the end of the coupling phase by means of angular fixing means consisting of a plurality of lugs arranged on the perifery of the complementary ring. The dentation at the front of the sleeve and the dentation of the complementary ring cover these elements totally or in part.

Abstract: A device for closing a transport duct for a liquid with the aid of said liquid, for example, a siphon, said device mainly comprising a housing (1) with a liquid chamber, a tube stub (4) connected in airtight manner with said housing (1) and reaching at the most up to the liquid chamber and a drain stub (5) opening out above the liquid chamber for connection with the transport duct (15), wherein around the pipe stub (4) there is arranged a body (8) capable of floating on the liquid, while airtight means (10) are arranged between the floating body (8) and either the pipe stub (4) or the wall of the housing (1), whereby it is no longer necessary to have the pipe stub (4) reaching into the liquid in the liquid chamber so that, when liquid is drained, a stream can directly flow beyond the liquid chamber towards the transport duct (15).