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Users who have used Yamada valve positioners know that these positioners, when used in combination with pneumatic diaphragm control valves, are widely applied in various fields such as the petrochemical and power industries. It is capable of converting the analog output signals from control systems such as DCS or PLC into air pressure signals used to drive pneumatic diaphragm control valves, thereby enabling rapid and precise positioning of the control valves as well as accurate regulation of thermal parameters such as flow rate, temperature, and liquid level. However, there are actually many types of Yamaku valve positioners: single-acting positioners used with pneumatic diaphragm control valves and piston actuators with spring mechanisms, as well as double-acting positioners used with piston actuators without springs. So how can one distinguish between single-acting and double-acting Yamada valve positioners? Taking a normally acting valve positioner and the actuator of a counteracting pneumatic diaphragm control valve as examples, assume that the signal output by the control system increases. In this case, the electromagnetic component of the valve positioner generates a force that causes it to move axially to the left, thereby reducing the distance between the baffle and the nozzle. As a result, the pressure in the backpressure chamber of the positioner’s actuator increases, and the diaphragm in this actuator pushes the valve element downward. This leads to an increase in the output pressure of the valve positioner, causing the actuator of the pneumatic diaphragm control valve to move upward and thus changing the degree of valve opening. This is how a single-acting valve positioner works. The double-acting valve positioner is not very different from it; aside from having two actuators and an additional connecting plate, everything else remains the same. But to distinguish them visually, one can check how many output ports the valve positioner has: a single output port indicates a single-acting positioner, while two output ports indicate a double-acting positioner. Moreover, each valve positioner is equipped with a pressure gauge at its output ports, which makes it easy to determine whether it is a single-acting or double-acting positioner. The Yamada SVP3000 Alphaplus series of intelligent valve positioners in Japan are microprocessor-based electrical valve positioners. It can receive a DC signal from a control device and control the opening of the valve. In addition to this basic function, the SVP3000Alphaplus also features communication capabilities, an automatic configuration program, and self-diagnosis functions, which enhance productivity and the efficiency of manufacturing processes. Valve positioners are classified into pneumatic valve positioners, electrical valve positioners, and intelligent valve positioners based on the input signal. The input signal of a pneumatic valve positioner is a standard pneumatic signal, such as a 20–100 kPa pneumatic signal, and its output signal is also a standard pneumatic signal. The input signal for electrical valve positioners is a standard current or voltage signal, such as a 4–20 mA current signal or a 1–5 V voltage signal. Inside the electrical valve positioner, this electrical signal is converted into electromagnetic force, which is then used to generate a pneumatic signal that operates the control valve. The intelligent electrical valve positioner converts the current signal generated in the control room into a pneumatic signal that drives the control valve. It compensates for the unbalanced forces resulting from fluctuations in medium pressure, due to the frictional forces on the valve stem during operation, thereby ensuring that the valve’s opening degree corresponds to the current signal sent from the control room. Furthermore, intelligent configuration can be used to set the corresponding parameters, thereby improving the performance of the control valve.