The ZXX/ZDLX series pneumatic/electric three-way control valves adopt a cylindrical thin-walled window-type valve core guide, which differs from the sleeve-type valve core's nested guide.

Equipped with a multi-spring actuator, the valve features a four-way structure, namely one-inlet-two-outlets (diverting type) and two-inlets-one-outlet (mixing type), thereby achieving mixed heating/cooling of fluids or unequal fluid distribution to meet the usage requirements of different working conditions. The valve boasts advantages such as compact structure, light weight, sensitive action, minimal pressure drop loss, large valve capacity, and convenient maintenance.

This series of products comes in various models, including standard, radiating, and bellows-sealed types. The nominal pressure ratings are PN(MPa) 1.6, 2.5, 4.0, 6.4, 10.0 (150lb, 300lb, 600lb); the valve body size range is DN(mm) 25–250 (1"–10"); suitable for multiple fluid temperature ranges from -40 to +450°C; leakage class: Class IV; flow characteristics include linear and equal percentage. Various specifications are available for selection.

Working Principle

Pneumatic ZXX:
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.

Electric ZDLX:
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