The ZXPII/ZXMII series pneumatic/electric low-noise control valves adopt a versatile and highly interchangeable modular design with a compact structure. They feature specially designed symmetrical small-port valve internals that reduce noise, achieve pressure reduction, and prevent flashing and cavitation. They are particularly suitable for various high-pressure differential and low-noise applications, meeting user requirements. The valve seat and valve body can be connected in a pressure-tight manner on both sides, effectively improving the sealing grade and stability of the valve, while also facilitating maintenance, thereby significantly enhancing the overall performance of the control valve.

This series of products comes in various models, including standard, radiating, low-temperature, and bellows-sealed types. The nominal pressure ratings are PN (MPa) 1.6, 2.5, 4.0, 6.3, 10.0 (150lb, 300lb, 600lb); the valve body size range is DN (mm) 20–200 (3/4"–8"); suitable fluid temperatures range from -196 to +560°C with multiple options within this range; leakage standards include Class IV, V, VI; flow characteristics include linear and equal percentage. Multiple specifications are available for selection.

Working Principle

ZXPII:
The positioner receives standard current signals or computer signals and converts them into valve position setpoints. The linear displacement of the actuator is converted into angular displacement through a connecting device and detected by a position sensor, which feeds back to the microprocessor.
The microprocessor compares the actual valve position feedback value with the setpoint. Upon detecting a deviation, it outputs a pulse-width modulation (PWM) command to the positioner valve based on the magnitude and direction of the deviation. The positioner valve adjusts the inlet or outlet volume of the actuator membrane according to the control command.

ZXMII:
After standard current signals or computer signals are converted via A/D, they enter the intelligent signal acquisition and control unit of the intelligent electric actuator.
The signal acquisition and control unit detects the input signal and position feedback signal in real-time. When these two signals are unbalanced, it outputs a pulse-width modulation (PWM) command to the bidirectional controllable silicon based on the magnitude and direction of the deviation, making it conductive and driving the motor to rotate in the direction that reduces the deviation. This, in turn, drives the speed-reducing mechanism and changes the valve opening.

Control Mode

The control mode is driven by PWM (Pulse Width Modulation):

• Full-speed state: When the control deviation is large, a continuous signal is output.
• Medium-speed state: When the deviation is not large, a pulse signal is output.
• Slow-speed fine-tuning: When the deviation is very small, a smaller pulse signal is output.
• Position holding: When the deviation is within the valve regulation accuracy range, no control command is output