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Concept of valve positioners: Valve positioners, classified by structure into pneumatic valve positioners, electro-pneumatic valve positioners, and intelligent valve positioners, are essential accessories for control valves. They are typically used in conjunction with pneumatic control valves; they receive the output signal from the controller and use this signal to control the pneumatic control valve. When the control valve moves, the displacement of the valve stem is fed back to the valve positioner through mechanical mechanisms, and the valve position is transmitted to the higher-level system via electrical signals. There are some common issues that arise when Siemens valve positioners are in use. Today, we’ve compiled some tips for keeping valve positioners dry, in the hope that they will be helpful to everyone! Functions of Siemens valve positioners in electrical systems: 1. When the fluid is viscous or contains solid particles suspended in it, using a positioner can reduce the resistance exerted by the fluid on the movement of the valve stem. 2. Improve the flow characteristics of the control valve. 3. Electrical valve positioners help to overcome the delay in the transmission of control signals, thereby improving the speed of valve response. 4. For control systems with high requirements for control quality, it is necessary to improve the positioning accuracy of control valves and enhance their reliability. 5. It should be installed in locations where the pressure difference across the valve is greater than 1 MPa; by increasing the air pressure, the output force of the actuator is enhanced, which helps to overcome the opposing forces exerted by the fluid on the valve core and reduces errors during operation. 6. When a single regulator controls two actuators, two positioners can be used – one for low-position operation and the other for high-position operation – to receive low input signals and high input signals respectively, thereby achieving stepped regulation. 7. To prevent external leakage, when the flowing fluid is at high temperature, high pressure, low temperature, or is toxic, flammable, or explosive, the filler is usually compressed very tightly, thereby increasing the friction between the valve stem and the filler; in such cases, an electrical valve positioner can be used to overcome any time delays. Functions of the pneumatic Siemens valve positioner: 1. Increase the thrust of the actuator. 2. Increase the speed of movement of the actuator. 3. Improve the flow characteristics of the control valve. 4. Achieve step control. In split-range control, two positioners are operated by one regulator, with the operating range of each positioner determined by the split points. 5. When a single regulator controls two actuators, two positioners can be used – one for low-level operation and the other for high-level operation – to receive low input signals and high input signals respectively, thereby achieving split-range control. 6. To prevent external leakage, when the flowing fluid is at high temperature, high pressure, low temperature, or is toxic, flammable, or explosive, the filler is usually compressed very tightly, thereby increasing the friction between the valve stem and the filler; in such cases, an electrical valve positioner can be used to overcome any delay in response. To learn more fun facts about instruments and meters, follow us~