Type YT-1000L Electro-pneumatic valve positioner is used for operation of pneumatic linear valve actuators by means of electrical controller or control system with an analog output signal of DC 4 to 20 mA or split Ranges.
Principle of positioner
(1) It is used in important adjustment systems that require high adjustment quality to improve the positioning accuracy and reliability of the adjustment valve.
(2) Used in occasions where the pressure difference between both ends of the valve is large (△p>1MPa). Increase the output force of the actuator by increasing the air source pressure to overcome the imbalance force generated by the liquid on the valve core and reduce the stroke error.
(3) When the medium to be adjusted is high temperature, high pressure, low temperature, toxic, flammable, and explosive, in order to prevent external leakage, the packing is often pressed tightly, so the friction between the valve stem and the packing is relatively large. Use the positioner to overcome the time lag.
(4) When the medium to be adjusted is viscous fluid or contains solid suspended matter, the positioner can overcome the resistance of the medium to the movement of the valve stem.
(5) It is used for regulating valve with large diameter (Dg>100mm) to increase the output thrust of the actuator.
(6) When the distance between the regulator and the actuator is more than 60m, the positioner can overcome the transmission lag of the control signal and improve the response speed of the valve.
(7) Used to improve the flow characteristics of the regulating valve.
(8) When one regulator controls two actuators to implement split-range control, two positioners can be used to accept low input signals and high input signals respectively, and then one actuator will act in low range and the other in high range, which constitutes a split range.
Commonly used actuators are divided into pneumatic actuators and electric actuators, which can be divided into straight travel and angular travel. It is used to open and close all kinds of valves, wind panels, etc. automatically or manually.
Pneumatic valve positioner working principle
The pneumatic valve positioner works according to the principle of torque balance. When the signal pressure P1 into the bellows 2 increases, the main lever 3 is rotated around the fulcrum, and the nozzle baffle 9 is close to the nozzle, and the nozzle back pressure is amplified by the unidirectional amplifier 8. After that, the pressure into the diaphragm chamber of the actuator increases, causing the valve stem to move downward.
And drive the feedback lever to rotate around the fulcrum, the feedback cam also rotates counterclockwise, the secondary lever 4 is rotated around the fulcrum through the roller, and the feedback spring is stretched. The tension and signal pressure of the spring on the main lever 3 are used in the bellows. When the upper force reaches the moment balance, the instrument reaches the equilibrium state.
Contact: Vison Chan
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Add: EAA Central Industrial Zone,Wenzhou,Zhejiang Province,China