The present invention relates to a valve assembly for insertion in a liquid flow path between a catheter or drain and a liquid bag or container. The valve assembly comprises a first valve member detachably coupled to a second valve member or coupling member by mating locking members. A first controllable valve is adapted to selectively block or enable liquid flow through the first valve member in accordance with a valve control mechanism which is responsive to a coupling state of the first and second locking members.
