Open vs. Closed Rotors
06/09/2024 - 08:49
A rotary valve is used to seal off the space above the valve from the space below it. The sealing in a rotary valve must therefore not only ensure a good separation between different pressure zones (static sealing) but also be resistant to the dynamic load of the rotating movement (dynamic sealing).
In a valve with an open rotor, the sealing is achieved with minimal clearance between the rotor and stator, as well as minimal clearance between the rotor and flanges on either side of the valve. A valve with an open rotor is often the standard choice because its application possibilities are very broad. Additionally, an open rotor offers better efficiency and a longer service life.
In a valve with a closed rotor, sealing also occurs between the rotor and the stator, but not between the rotor and the flanges. A closed rotor is significantly stronger than an open rotor, making it highly suitable for valves used under heavy loads where breaking and cutting of the material are necessary, as well as for valves with large diameters (> approx. 600 mm). Additionally, a valve with a closed rotor is simpler to produce and, therefore, more cost-effective.
