US Patent 7784651 Foam throttle

A tap for removing liquid from a container has a sleeve (10) made of plastic, in which a piston (12) is guided, and which sleeve has a passage opening (28) for the liquid. A hood that can be set onto the sleeve (10) in front of the passage opening (28), so that it covers the passage opening (28), serves as a foam throttle. The hood encloses a labyrinth channel (36), together with the sleeve, which channel is open at one end, towards the interior of the container, and ends in the passage opening (28) at the other end.