A wound drainage device flow regulator (40) for controlling fluid flow from a wound to a container. The regulator (40), in use, provides selective communication between a conduit and the container. The device incudes a valve for communication between the conduit and the container in response to a level of vacuum in said conduit below a selected value. The valve has a diaphragm (75) exposed to atmospheric pressure on one side and to the level of vacuum in the conduit on the other side, and an adjustable force means arranged to apply a force to the diaphragm (75) in opposition to the atmospheric pressure, the difference between the force applied by the adjustable force means (74) and the force generated by the atmospheric pressure providing a control force required to be applied by the level of vacuum in the conduit to close the valve means to interrupt communication between the container (62) and the conduit 66, and a lock mechanism (70) arranged to lock the adjustable force mechanism (74) at a desired adjustment corresponding to a desired level of vacuum.
