Abstract: A valve for controlling a flow of process fluid, the valve including a housing; a shaft having a closing member, the shaft being received in the housing, and arranged to move axially relative to the housing; an outer seal arrangement for preventing process fluid from entering the housing, the outer seal arrangement including at least one dynamic radial outer seal enclosing the shaft; an inner seal arrangement, axially spaced from the outer seal arrangement along the shaft, the inner seal arrangement including at least one dynamic radial inner seal enclosing the shaft; and a buffer liquid chamber containing buffer liquid, the buffer liquid chamber being configured to provide buffer liquid to the shaft, and being arranged between, and sealingly closed by, the outer seal arrangement and the inner seal arrangement.