Connecting device for coupling a section of hose to a conduit section

The connection device (1) has a connecting piece (3) with a receiving device for fastening the hose section (2) and with a mounting device (8) for connecting the connecting piece with the housing part (5). The connecting piece has a sealing device with a sealing surface facing the valve body (11). The valve body has sealing surfaces facing the connecting piece, which are arranged such that the sealing surfaces lie together in a sealing manner in the closed position of the valve body. An independent claim is also included for a brake system of a motor vehicle with a brake hose.