As you can see from the above the eccentricity between the shaft and rotors causes the chambers formed between the rotor and blades to vary in size as the pump rotates. The liquid entering the pump is guided in to the ends of the rotor and then back out through the discharge port.

There are eight pumping sectors and the illustration shows how the sector increases and decreases in size during rotation. Each sector in turn acts in the same manner, causing the continuous pumping action.

The 2000 series blades are gently sliding along a flat inside the rotor, thus reducing wear and maintaining high volumetric efficiency.

So why do Plenty use a rotor and blades in this way?

In the Plenty rotary pump the top is flat which gives a large rectangular area of contact and in one revolution travels up and down the short face on the rotor once. The result of this is that in one revolution a Plenty blade tips slides approximately only one tenth of the movement than some other pumps.

It should not be overlooked that the periphery of the rotor in the Plenty rotary pump travels roughly the same distance that a standard rotary tip does so a high wear rate at the body/rotor interface might be expected. However the contact here is similar to that of a plain journal bearing with a large area of contact around which hydrodynamic pressures are generated to support it and in practice a low wear rate is seen in this area.

The large rectangular area of contact between the blades and the rotor gives reduced slip (or internal leakage) at the blade tip and therefore gives high volumetric efficiency.

In the Plenty rotary pump the blades are continuous (shaped like an ‘H’) passing through the shaft and two half blade butting and overlapping each other in the middle of the shaft. As the blade tips wear very little this ensures that close contact with the rotor is maintained.

Also because there are only four blades located at one position on the shaft the blade thickness can be made high without weakening the shaft resulting in a greatly reduced chance of blade/shaft fracture.

Because the pumping cavities are not in direct contact with the body bore; turbulence due to the cavity moving rapidly over a stationary surface is greatly reduced. This results in a much improved gentle pumping action which imparts low shear rates to shear sensitive products (ie Additive, Polymers, Inks etc.) and considerably reduces the risks associated with foaming of the product which can cause severe production, quality and dispensing problems.

The unique rotating assembly consists of 8 working blades made up as 2 sections set 45 degrees apart, each section consisting of 2 half blades and 1 "H" blade.