Side-Entry Impeller Positioning



Side-Entry drawing by Geoff Graham

 How do we achieve maximum mixing in a side-entry application? It's not by chance, or trial and error. Rules definitely apply here. Let's take a look:

The rule of thumb for positioning a side entry impeller is a minimum of 1/3 the impeller diameter off the wall.

• H = Distance off wall

D = Impeller diameter

“Suction” area = pD x H

“Discharge” area = pD²/4


Suction = discharge in order to avoid “starving” impeller flow.

pD x H = pD²/4
H = D/4

So, for a flat wall H is constant.

For a curved wall, H is going to vary. 1/3 D is pretty close to ¼ D, and as it is slightly longer, more forgiving of wall curvature, etc.

Sharpe Mixers has been sizing side-entry mixers for for many years. These industries include asphalt mixing, pulp & paper, waste water, petroleum, storage tanks and more. How can we assist you? Let us know what your needs are and we can size a side-entry mixer for you today!

Submitted by Steven F. Drury, P.E.

Industrial Laundry Wastewater Treatment

Ever been to a process plant where personnel wear uniforms?

Ever seen uniform rental trucks driving to and from those plants?

All those uniform rental companies washing all those dirty clothes.

And what happens to all the waste water from all those laundries?

The EPA requires that all industrial laundry wastewater be pre-treated before being discharged to the municipal treatment plant.

The wastewater must have pH adjusted; dirt, oil and grease removed.

A common pre-treatment operation consists of two equalization-pH adjustment tanks followed by DAF, Dissolved Air Flotation, to remove dirt, oil and grease.

The equalization-pH adjustment tanks are in the 5,000 – 10,000 gallon range.

Each is equipped with top entry mixer.

The DAF system uses polymer as a coagulant aid. The polymer is usually mixed ahead of the DAF using a gear drive portable mixer.

Sharpe Mixers has been working with one of the world’s largest uniform rental companies for over 10 years, supplying the mixers for their waste treatment plants. We have shipped mixers to their plants all over North America and the United Kingdom.

So, next time you see a uniform rental company truck driving down the road, follow it back to the laundry and see what they are doing for pre-treatment of their industrial laundry wastewater.