A major disadvantage of conventional butterfly and ball valves when used in throttling applications is the effect of cavitation which can commence at quite low values of differential pressure. This, coupled with high noise emissions may result in rapid mechanical wear and early failure of the valve components.

To offset these effects, we have developed a rotary control valve with improved performance capability. The innovative design incorporates a profiled vane which has cowls on its leading and trailing edges. These cowls are drilled with a large number of holes as can be seen above. The function of these cowls, which normally cover about one third of the 90º travel, is to split up the flow stream and dissipate the energy created by the pressure drop across the valve. This allows the valve to handle higher pressure drop and higher velocities without the onset of cavitation and noise. This specialized valve performs exceptionally well in severe service applications with its variable resistance trim, where the pressure drop tends to be high in the controlling position but where high capacity through puts at low pressure drops are also required.