Baffle Designs

Mixing low viscosity liquids may lead to vortexing, if vigorously agitated. Vortexing increases with impeller speed, until the vortex reaches down and moves through the impeller. Mixing efficiency is reduced for vortexing systems compared to non-vortexing systems, and baffles are then required.

Baffles must be used with low viscosity mixing processes, when top entry mixers or propeller types are located on the centreline. Un-baffled tanks will result in wide power variations, making predictable loading difficult and motor under-loading probable. Without baffles, only the easiest agitation requirements could be satisfied – those requiring extremely low power inputs.

“Standard” baffles are one-twelfth the tank diameter in width and four in number, equally spaced.

As liquid viscosity increases, however, the need for baffles to reduce vortexing decreases. For viscosities over 100 cp, baffle sizes should be reduced.

With high viscosity liquids, baffles are most effective when positioned away from the tank wall. When turbines and marine propellers are used to mix liquids of viscosities greater than 10,000 cp, baffles are not required. The liquid’s natural resistance to flow becomes self-baffling and dampens vortexing due to liquid swirl.

These guidelines and notes are presented as general guides only and no warranty is implied or provided.