Regelkranen

Regelkranen, in English commonly called control valves, are devices used to regulate the flow rate, pressure, temperature or level of fluids in piping systems. They achieve regulation by varying the effective flow area through the valve trim in response to a control signal, distinguishing them from isolation valves that are simply open or closed.

A regelkraan consists of a valve body with a flow-restricting element (trim) and an actuator that moves the element. The actuator can be pneumatic, electric or hydraulic. A control signal, often 0-10 V or 4-20 mA, drives the actuator. In many installations a positioner or a control loop ensures the valve reaches the commanded opening and maintains the desired process variable.

Key components and concepts include the valve body and trim, seat, actuator, and sometimes a positioner or feedback sensors. The flow characteristic is described by the Kv or Cv value, and the relation between signal and flow depends on the trim design (linear or equal-percentage). Material selection and trimming influence durability, corrosion resistance, and noise.

Common types include globe-style control valves, which provide good throttling control, and other valve types such as ball or butterfly valves used for larger sizes or different service conditions. Trim and actuator options vary, including anti-cavitation or low-noise trims and explosion-proof actuators for hazardous environments.

Design and selection considerations cover sizing (Kv/Cv), acceptable pressure drop, potential cavitation or flashing, noise, corrosion resistance, and temperature limits. Proper installation, orientation, and piping arrangement are important, as is regular maintenance, calibration of positioners, and replacement of worn trim.

Applications span process industries such as oil and gas, chemical, power generation, and water treatment, where precise flow regulation is essential for safety, efficiency, and product quality.