Variable inlet vanes are highly efficient at maintaining volume control, offer more control than box dampers and lower part load power consumption. These radial inlets have control dampers that can be used with open inlet fans or fans with inlet boxes. For high temperature fan applications, such as ID fan service, the mechanism can be isolated from the gas stream.

External linkage radial vane dampers are also highly efficient at maintaining volume control. Having the bearings and linkage outside of the casing promotes longer life and allows for operation in particulate-laden applications. Routine maintenance can also be performed on the bearings and linkage while the fan is in operation.

Clarage designs and manufactures both opposed blade (MLOB) and parallel blade (MLPB) multi-louver dampers. MLOB dampers are commonly used on fan outlets. MLPB dampers, when used on fan inlet boxes, provide increased fan efficiency at reduced loads. Rugged construction is a featured quality of these types of dampers.