A fluid flow regulation system has an inlet, an outlet, and an adjustable
flow regulator connected between the inlet and the outlet. The regulator
has a closed position at which a leakage gas flow through the system is
established. An extraction device is provided for fluid connection with
one or both of the inlet and the outlet and is operable to extract fluid
to provide a zero or negative flow from the outlet when the flow regulator
is in the closed position.
