Throttling only or non-pressure-compensated valve
This type of valve is used where the system pressures are relatively constant and the motoring speeds are not too critical. They work on the principle that the flow through an orifice will be constant if the pressure drop remains constant.
The figure of a non-pressure-compensated valve shown in Figure 6.34 also includes a check valve which permits free flow in the direction opposite to the flow control direction. When the load on the actuator changes significantly, the system pressure changes. Thus, the flow rate through the non-pressure-compensated valve will change for the same flow rate setting.