Abstract: A valve system and a fluid flow system with a valve system are disclosed. The valve system comprises a valve housing defining a fluid inlet for receiving a fluid medium, and a fluid outlet for delivering a fluid medium; at least one valve element arranged in an interior part of the valve housing, the valve element(s) being movable relative to the valve housing, the position of the valve element(s) relative to the valve housing determining a flow rate of fluid medium through the valve system from the fluid inlet towards the fluid outlet; a moving mechanism arranged to cause movements of the valve element(s); and a sealing member arranged in an interior part of the valve housing, the sealing member being capable of separating the interior of the valve housing into a first part comprising the fluid inlet and the fluid outlet, and a second part.