Abstract: Coupling element for connecting two pipe ends. The coupling element includes a housing with a first connecting end, a second connecting end, and a connecting channel formed between the first and second connecting ends, and a vent duct having a passage covered by a hygroscopic seal and a vent valve that includes a valve seat and a valve element arranged in series with the hygroscopic seal and the passage. The valve element is structured to be lifted from the valve seat by a pressure in the connecting channel.

Abstract: A fluid line of thermoplastic material includes a first end section integral with a principal part of the fluid line which is at least partially undulated. A first holding rib engages behind at least one locking projection of a connecting ring. The ring engages behind a second holding rib on a second end section of the pipe. The first end section has an essentially conical initial section located adjacent the principal part of the fluid line. The initial section has an outer diameter which increases in a direction toward the free end of the first end section. The initial section is adjacent to an intermediate section whose outer diameter decreases from the greatest diameter of the initial section to the smallest diameter of a locking groove for the engagement of a first locking projection.

Abstract: A fluid line of thermoplastic material includes a first end section integral with a principal part of the fluid line which is at least partially undulated. A first holding rib is provided for engaging behind at least one locking projection of a connecting ring. The ring has at least one second locking projection for engaging behind a second holding rib on a second end section of the pipe. The first end section is insertable into the second end section for connecting the fluid line to the pipe. The first end section ahs an essentially conical initial section located adjacent the principal part of the fluid line. The initial section has an outer diameter which increases in a direction toward the free end of the first end section. The initial section is adjacent to an intermediate section whose outer diameter decreases from the greatest diameter of the initial section to the smallest diameter of a locking groove for the engagement of a first locking projection.