Coaxial shaft agitators

Coaxial shaft agitators are double acting units equipped with two agitator systems, each with its own independent drive and control system. The double drive system enables the combination of different process steps, such as blending, suspending, dispersion and heat transfer. This is a cost-efficient alternative to blenders and horizontal mixers.

Drive units

SKR Coaxial Shaft Series drive units transmit power from two electric motors to the coaxial agitator shafts and transform the motor speeds to the nominal agitation speeds. The drive unit also works as the housing for various sealing systems and bearings. The input power range is 1.5 – 160 kW and the shaft diameter range 40-200 mm.


Coaxial agitators are designed to handle viscosities from water-like fluids up to 1 million centipoises in one process. Double acting agitation cases require tailored impellers based on helical blades or other generic impeller designs. In addition to these generic impellers, UTG offers proprietary impellers and customer requested impeller designs.



Sealing is required for isolating the reactor gas space from the ambient atmosphere, for example due to pressure differences or hazardous gas.


Bottom support

In order to strengthen the system, additional bottom supports are occasionally applied in the agitator design. Bottom supports giving the shaft a second fulcrum are normally applied to structures with extra tall shafts or high bending moment. Generally, bottom bearings are avoided as they always increase the number of maintainable parts.


Mounting to tank

Most of the drives are mounted directly to the tank flange.



Materials are selected based on corrosion and abrasion conditions inside the tank. Mechanical properties in relation to the required agitation forces also play a role when selecting materials. Ideally, solid materials are applied, but sometimes linings have to be used due to the availability, cost or a poor combination of wear and mechanical strength of the base material.