Abstract: The receiving unit can be removed from the valve unit and fastened preferentially by means of a fast locking means, in particular of a bayonet lock, a thread or a plug-in lock. The valve unit is spring-biased in the closing direction and opens toward the inside. The receiving unit is spring-biased in the closing direction and opens toward the outside. The valve unit and receiving unit are linked in sealing connection preferentially by means of mating ball joints. At the valve unit a discharge bore hole may lead from the discharge opening toward the outside the valve bar being located outside the discharge bore hole. At the lock the closure bar may extend outward from the opening of the receiving unit. The actuating device acts on the lock of the receiving unit preferentially by a two-part driver device with a cam coupled to the closure housing and a recess arranged at the closure bar.