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Progressive cavity pumps are self-priming rotary positive displacement pumps with smooth output flow.
They are capable of pumping both thick and thin fluids, and do very well at pumping liquids with high solids and abrasive content. These capabilities have made the progressive cavity pump the pump of choice for many applications in the wastewater treatment industry.
In recent years, advances in pump design, electronic monitoring and materials of construction have allowed the progressive cavity pump to handle more severe application conditions, while at the same time improving the pump’s energy efficiency and decreasing maintenance requirements.
The purpose of this article in WWD’s Pump Source is to give an overview of the progressive cavity pump’s operating principle. The article will also review some of the new technical innovations that end users may be able to benefit from when it comes to selecting this type of pump for their wastewater applications.
Rene Moineau invented the progressive cavity pump in France in the 1930s. The pumping element is made from the rotor and stator elements.
Normally, the rotor is made of steel and is the shape of a single helix external shape. The stator is normally made from an elastometer and is the shape of a double helix internal shape. The rotor is manufactured to be slightly larger in size than the stator so that there is an interference fit when the rotor is inserted into the stator. As the rotor turns inside the stator, a cavity is formed between the two shapes and progresses axially from one end of the element to the other (Figure 1).
The progressive cavity pump is made of three major sections: the pumping element, the suction housing and the drive train (Figure 2).
In recent years, many improvements have been made in these areas to improve the pumps overall performance.
Improvements in drive train design