A radial vane inlet controller (sometimes known as a vortex damper) consists of a number of segment shaped blades enclosed in a circular casing, each pivoted along its axis of symmetry and linked in such a way that all blades maintain an identical angle to the axis of the device. In this way the unit imparts a variable amount of swirl to the air (or gas) stream. Its normal application is therefore the regulation of centrifugal fans.
The blades are connected via an external ring. Rotation of the ring causes the blades to open, each blade moving at the same rate as the others. The linkage between the ring and blades is designed so that, with blades almost shut, large movements of the ring cause small blade movements. This results in fine control at large turn downs. At near full open settings where the position of the blades is less critical, the effect is reversed. The mechanical advantage of the linkage in the near closed position is also enhanced providing maximum torque where the requirement is greatest.
The blades have minimum cross section area consistent with the mechanical strength required, so that pressure losses through the controller are restricted to a minimum. The boby has a central hub carrying the inboard bushes, the outboard bushes being supported in machined bosses welded to the main drum. All bushes are self lubricating. They in turn support the stainless steel stub shafts which are welded to the blades
The operating ring is a rolled stainless steel channel section running on high molecular weight engineering plastic support rollers. Attached to each outer blade shaft is our unique linkage configuration which allows precision adjustment of individual blades. The operating levers are keyed to the shafts for security and to prevent loss of adjustment.
Any type of actuator can be supplied, including manual hand wheel, pneumatic, electric and hydraulic. The illustration shows the mountings for the guards, which are always fitted on powered units. (Please see the illustrating of our hub-less IVC for a unit with guards fitted).