These pumps are used in many areas. Progressive cavity pumps can be used to pump liquids such as water as well as highly viscous materials and even solids. However, these pumps are mostly used where other types of pumps cannot be used or can only be used with great restrictions.
How do progressive cavity pumps work?
This pump consists mainly of two parts: the rotating rotor and the fixed stator. The rotor is shaped as a round-thread screw with a small core diameter, a large depth and a very large pitch. The stator has twice the pitch length and one thread more than the rotor. The stator is made of an elastic material. Between the rotating rotor and the stator, conveying spaces are created which constantly move from front to back. The size of the pump determines the size of the delivery spaces. It also determines the maximum flow rate per revolution of the rotor. The actual flow rate of the pump can be varied by the rotational speed. This type of pump was invented by the Frenchman René Moineau and a patent was applied for in 1930.
The advantages of progressive cavity pumps
These pumps do not require valves to seal the delivery chambers. This means they require less maintenance and have a longer service life. The shape and size of the delivery chambers remain constant. Therefore, the conveyed material is not compressed. Only very small shear forces act on the material being conveyed. Therefore these pumps are also suitable for pumping sensitive solids, such as whole fruits. In general, the conveyance with these pumps is gentle, because it is low-pulsation and pressure-stable. Since the eccentric screw pump is a positive displacement pump that does not require valves, it can also be used to convey fibrous materials.
Applications of the progressive cavity pump
In papermills, in addition to paper raw materials and groundwood pulp, glue and paint must also be transported. There, the pumps have to transport crumbly, viscous, liquid and chemically aggressive media.
The food industry also makes numerous different demands on the pumps used. For example, when harvesting olives or fruit, the fruit must be transported gently. In the production of confectionery, on the other hand, highly viscous substances, such as dough or marzipan paste, must be pumped.
The chemical industry also places very high and very different demands on the pumps used. There, everything from liquids to viscous mixtures and solids must be transported. In addition, the material of the pump must not be attacked by the chemicals.
The construction industry uses eccentric pumps as mortar and plaster pumps. These are extremely abrasive materials. Nevertheless, a permanent use of the pumps is of course required. In any case, the rotor is insensitive to abrasive materials. The stator must be made of an appropriate material mixture to ensure a long service life of the pump.
In environmental technology, these pumps are preferably used in sewage treatment plants to transport sludge and wastewater.
The civil protection also appreciates these pumps. They like to use them to pump off oil sludge or chemicals of all kinds.