Absolute error of valve control position is reduced in full stroke

The EXPRO valve actuator can accurately control the flow cross-section of the valve during the full stroke of the valve, because the closer it drives the valve to the closing position of the valve, the smaller the absolute position control error of the valve. In theory, the absolute position error at the closing position of the valve is zero. Regulating valves controlled by general industrial valve actuators, when the flow cross-section is very small, the relative error of the position control is the EXPRO valve actuator can accurately control the flow cross-section of the valve during the full stroke of the valve, because it drives the valve closer to the valve to close Position, the smaller the valve's absolute position control error, theoretically speaking, the absolute position error at the valve closed position is zero. For regulating valves controlled by general industrial valve actuators, when the flow cross-section is very small, the relative error of position control will become very large. The main reason is that general industrial valve actuators can only provide a relatively constant drive position error. For example, a control poppet valve has a 30o valve core, and the valve seat has a sharp, right-angled edge. It is driven by an ordinary hydraulic valve actuator, assuming that the position control error of the hydraulic valve actuator is 0.5 mm. The valve inner diameter is 25 mm, and the valve stroke is 40.77 mm. When the valve is fully opened, the relative error of the valve position control is 0.5 mm/40.77 mm X100% u003d 1.2%, the flow section of the valve is 490.9 mm2, and the relative error of the flow section is 0.38%. When the valve stroke is 2.48 mm from the valve closed position, the relative error of the valve position control is 0.5 mm/2.48 mm X100%u003d20.2%, the flow section of the valve is 49.2 mm2, and the relative error of the flow section is 9.6%. When the valve stroke is 1.00 mm from the valve closing position, the relative error of valve position control is 0.5 mm/1.00 mm X is 1100%u003d50%, the flow section of the valve is 20.1mm2, and the relative error of the flow section is 49.5% . Please see the red curve in Figure 3 and Figure 4. If this control poppet valve is driven by EXPRO LL valve actuator, and suppose that the position control error of the input hydraulic cylinder is 0.5 mm. When the valve is fully opened, the relative error of the valve position control is 0.487 mm/40.77 mm X100% u003d 1.2%, the flow section of the valve is 490.9 mm2, and the relative error of the flow section is 0.37%. When the valve stroke is 2.48 mm from the valve closed position, the relative error of the valve position control is 0.094 mm/2.48 mm X100%u003d3.8%, the flow section of the valve is 49.2 mm2, and the relative error of the flow section is 3.7%. When the valve stroke is 1.00 mm from the valve closing position, the relative error of valve position control is 0.059 mm/1.00 mm X100%u003d5.9%, the flow cross section of the valve is 20.1 mm2, and the relative error of the flow cross section is 49.5%. Please see the blue curve in Figure 3 and Figure 4. The superiority of using EXPRO valve actuator to adjust the flow is very obvious. The use of EXPRO valve actuators can significantly improve the accuracy of flow control and increase the control range of the valve.