Kontrollventiler

A kontrollventil, or control valve, is a valve whose primary function is to regulate the flow, pressure, or level of a process fluid by adjusting the size of the passage. The valve position is controlled by an actuator driven by a signal from a process controller, forming part of a feedback control loop.

Actuation may be pneumatic, electric, or hydraulic. The actuator moves a plug, disk, or globe-style trim against a seating surface. A positioner or servo amplifier may be used to achieve accurate positioning and to convert the control signal into valve travel. In many systems the control signal is a standard current or voltage, commonly 4–20 mA, with position feedback.

Common valve types used as control valves include globe valves for precise throttling, and, depending on the application, ball, butterfly, or diaphragm valves. The flow is characterized by the flow coefficient Cv (or Kv); sizing and selection consider rangeability, maximum differential pressure, and potential for cavitation, flashing, or noise. Trim materials and seat seals are chosen for compatibility with process fluids and temperatures. Anti-cavitation or noise-reducing trim may be used in demanding services.

Applications span chemical processing, oil and gas, power generation, water treatment, and pharmaceuticals. Key standards related to control valves include IEC 60534-2 and ISA standards for sizing and control valve performance, and general quality standards such as ISO 9001. Proper installation, calibration, and maintenance are essential for reliable control.