A proportional valve for water controls fluid flow rate by changing the size of the passage through a restrictor. The controlled flow rate adjusts the parameters that affect a process, such as temperature, pressure, level, and pressure. Other minor parameters include weight and thickness, humidity, density (PH, color), and viscosity. An actuator is a controller that sends a signal to the automatic control valve. The signal directs the restrictor.
A proportional flow control valve pneumatic water uses a solenoid to flow adjustment valve position. Direct-operated two-way standard proportional solenoid operates in a similar fashion to a solenoid valve. However, the former can position the valves through a variety of positions while the latter has only two switching states (i.e., on/off).
Although it is theoretically possible to control the plunger proportionally with variable DC voltage, static friction on the guide points causes the valve’s sensitivity to be less sensitive. This leads to greater hysteresis (a phenomenon where the value of a property is not affected by changes in the cause). Special control electronics can convert the normal inlet signal into a pulse width modulated potential signal (PWM) to prevent static friction.
PWM (pulse-width modulation) is a technique that allows control over the power supply to electrical devices. The solenoid can control the average voltage and current by turning the power switch fast on/off. This control causes the plunger to oscillate at a weak but fast rate. The oscillation places the plunger in a stable state that maintains its constant sliding friction. Fluid flow behavior is not affect by the oscillation motion of the plunger.
The total power supply to the solenoid will be higher if the switch is left on longer than the off periods. The duty cycle is the ratio of on-time (t1) to the duration of the cycle, T. Low duty cycles correspond to low power as the power is off for most of the time. The duty cycle is express as a percentage, with 100% representing fully on.
The spring pulls the solenoid control valve to a closed position. This is done by feeding zero current to the coil. The coil produces a magnetic field that moves the plunger against the return spring by applying current. The solenoid is power at 100%, and the valve remains open. The flow of the fluid control valve is affect by the duty cycle. A 50% duty cycle fed to the solenoid would move the spring and plunger to 50% of their operating range. Understanding the operating method of proportional valve for water can help you control it better.
Types of Proportional Valves:
- Directional Control Valve:
These valves can be use for direction control in many hydraulic applications. These valves are primarily use in closed-loop applications. Some proportional directional control valves don’t have spool feedback. These are design for open-loop control applications.
- The Proportional Flow Control Device:
An integrate compressor or hydrostatic can be use to limit the pressure across the throttle orifice. The flow will not change if the load force changes. A proportional valve for water is directly responsible for flow of water/fluid. . A liquid flow control solenoid valve can be piloted or directly operated.
- Proportional Pressure Relief Valve:
These valves are commonly use to limit pressure in hydraulic circuits. This limit can indeed be adjust electronically. The pressure-relieving process would produce excess flow. This overflow is direct into the reservoir chamber.
Examples of Applications:
- The Mixture Of Warm And Cold Water:
A Pt100 temperature sensor measures the temperature of the mixed liquid. This temperature controller adjusts two solenoid control valves to bring it down to the reference temperature.
- Temperature Control:
According to the process water temperature, the solenoid control valve adjusts the water supply to the heat exchanger. More cold water is need if the temperature is higher than the reference. Cooling it down if it is less than the reference value is recommend. Similar principles apply to a heating circuit.
- Flow Control:
A proportional valve for water may be used as a direct flow control valve. Actuator Control: Two solenoid control valves can control the airflow for the pneumatic drive (piston, cylinder, etc.). The PID controller controls which valves should be open. The high-pressure flow control valve controls the drive so that the process value matches the set point. A proportional control water flow valve is mostly use in industries.