Abstract: A control valve comprises a valve housing (1) having an inlet side (17) and an outlet side (18). The control valve also has a pressure maintaining arrangement for maintaining a constant differential pressure between the inlet and outlet sides, as well as an amount control arrangement for setting the maximum flow through the valve. A pair of cylinder shells located in the flow path have cooperating recesses which provide an uncovered area forming an opening (25). One cylinder shell is rotatable relative to the other cylinder shell by a rotatable handle (13), whereby a larger or smaller opening (25) between the cooperating cylinder shells may be provided. Both cylinder shells are axially displaceable within a seat hole (8), resulting in an increase or a decrease of the opening (25).

Abstract: The control valve according to the invention is for use in liquid carrying systems. It comprises a valve housing (1) having an inlet side (17) and an outlet side (18), said valve housing being provided with a pressure maintaining arrangement for maintaining a constant differential pressure between the inlet and outlet sides, as well as an amount control arrangement for setting the maximum flow amount through the valve and adjustment of it. The control arrangement comprises two cylinder shell elements (2 and 3) cooperating in the flow path, both having material removed from otherwise overlapping areas, thereby generating an uncovered area (25) in the flow path of the control valve. The outer cylinder shell element (3) is stationary rotatable relative to the valve housing, while the inner cylinder shell element (2) may be rotated by means of a rotatable handle (13), whereby a larger or smaller opening (25) between the cooperating cylinder shell elements (2 and 3) may be provided.