Valvecontrolled

Valve-controlled refers to systems in which flow, pressure, or liquid level is modulated primarily by adjusting a valve opening, rather than by directly controlling the supply source. In these systems, the valve position is typically part of a closed-loop control that seeks to reach and maintain a setpoint.

Operation and components: A valve, an actuator (electric solenoid, pneumatic cylinder, or hydraulic actuator), a controller, and sensors form a feedback loop. The controller computes a command from the difference between measured values and a setpoint, and moves the valve accordingly. Common control strategies include PID and other model-based methods.

Applications: Valve-controlled regulation is common in water distribution, irrigation, chemical processing, HVAC hydronic systems, and industrial automation. It is also used in laboratory instrumentation and microfluidic devices where precise flow routing or pressure regulation is required.

Advantages and limitations: Valve control can provide precise, scalable regulation and energy efficiency by limiting pumping or compressor loads. It allows rapid changes in flow and isolation of process streams. Drawbacks include system complexity, valve wear and leakage, potential instability if not tuned, and sensitivity to supply dynamics and valve response time.

Valve types and actuators: Common valve types include globe, needle, proportional, and servo valves, paired with electric solenoids, pneumatic, or hydraulic actuators. Feedback may be provided by flow meters, pressure sensors, or level sensors, and control may be implemented with local controllers or industrial automation networks.