A valve assembly is reported for controlling the flow of fluids between the inlet and outlet of a fluid valve. The valve assembly contains a barrier element which is porous for providing fluid communication between the valve inlet and outlet. The valve assembly also includes a sealing element that is movable relative to the barrier element between a first position, in which fluid flow through the porous portion of the barrier element is blocked preventing fluid communication between the valve inlet and outlet, and a second position, in which the porous portion is unblocked, permitting fluid communication between the valve inlet and outlet
