A conduit coupling for connecting a first conduit to a second conduit to open or block a medium passage for low temperature media, comprising: - a first coupling half arranged in the course of the first conduit, which comprises a first tubular housing with an outer coupling groove, and a poppet valve with a spring biased valve disk that normally blocks the medium passage but can be pushed open; - a second coupling half arranged in the course of the second conduit, which can be placed onto the first coupling half to cause a coupling pin to engage in the coupling groove of the first coupling half, wherein the second coupling half comprises a second, three-part housing including a tubular jacket housing, a bell-shaped drive housing and a valve housing, and a stem-actuated valve including a valve stem and a valve piston that normally blocks the medium passage through an axial annular gap on the valve housing but clears the medium passage when being displaced axially by the drive housing, wherein the drive housing can take different rotational movement positions in order to cause the coupling pin to engage in and disengage from the coupling groove and to rotate a cam groove provided on the drive housing, to thereby drive a stem pin of the stem-actuated valve and the valve stem, and to guide the valve piston into the opened or closed position, and to actuate the poppet valve of the first coupling half; and - a first spreading lip seal which has a sealing body disposed in an annular groove of the valve piston and sealing lip facing radially outwards, and which serves as an element of the valve piston to close or open the axial annular gap between the valve housing and the valve stem depending on the movement position of the drive housing. - a first coupling half arranged in the course of the first conduit, which comprises a first tubular housing with an outer coupling groove, and a poppet valve with a spring biased valve disk that normally blocks the medium passage but can be pushed open; - a second coupling half arranged in the course of the second conduit, which can be placed onto the first coupling half to cause a coupling pin to engage in the coupling groove of the first coupling half, wherein the second coupling half comprises a second, three-part housing including a tubular jacket housing, a bell-shaped drive housing and a valve housing, and a stem-actuated valve including a valve stem and a valve piston that normally blocks the medium passage through an axial annular gap on the valve housing but clears the medium passage when being displaced axially by the drive housing, wherein the drive housing can take different rotational movement positions in order to cause the coupling pin to engage in and disengage from the coupling groove and to rotate a cam groove provided on the drive housing, to thereby drive a stem pin of the stem-actuated valve and the valve stem, and to guide the valve piston into the opened or closed position, and to actuate the poppet valve of the first coupling half; and - a first spreading lip seal which has a sealing body disposed in an annular groove of the valve piston and sealing lip facing radially outwards, and which serves as an element of the valve piston to close or open the axial annular gap between the valve housing and the valve stem depending on the movement position of the drive housing.