In addition to the rotor and stator, the classic design of the progressing cavity pump also includes the power train, a shaft seal, the suction and discharge casing and the drive. This is how progressing cavity pumps are constructed:
Rotor of the progressing cavity pump
The helically wound rotor moves in a rotating, oscillating manner in the stationary stator. It is around a threaded screw with a large pitch, a significant thread depth, and small core diameter. It is hinged or elastically mounted on one side. NETZSCH offers numerous different geometries. The same design of progressing cavity pumps results in a modular construction system. This allows you to adjust the flow rate and pressure of installed pumps even later by replacing the rotor-stator unit. Rotors for progressing cavity pumps from NETZSCH are available in wear- and corrosion-resistant designs up to the wear-free ceramic rotor NEMO CERATEC®. The most significant advantage of ceramic rotors over metallic ones is their physical hardness; only diamond is more complex. All media with which the NEMO CERATEC® comes into contact are softer than this. This excludes the possibility of damage to the contact surfaces. Ceramic rotors thus offer you extremely high wear resistance.
Stator of the progressing cavity pump
The stator is the second elementary component in constructing the progressing cavity pump. It is hollow and has an elastic wall. The stator has the same geometrical proportions as the rotor but has a different number of gears. This creates conveying spaces between the stator and the rotor, which rotate inside and remove, moving continuously from the inlet to the outlet side. The medium is thus transported gently and constantly from the suction to the discharge side by the rotary movement. The size of the delivery chambers and, therefore, the theoretical delivery rate depends on the pump size. You can quickly determine the flow rate via the rotor/stator pitch, diameter and eccentric, and the pump speed. NETZSCH offers stators in a variety of elastomers, plastics and metals. This gives you the optimal material combination for your applications and thus increases efficiency. With the environmentally friendly iFD-Stator® 2.0, you can significantly reduce the service life and, therefore, your life cycle costs. It consists of a reusable housing with a polygonal profile and the inserted elastomer. The innovative design enables you to change the stator more easily. The iFD-Stator® 2.0 is compatible with all NEMO® progressing cavity pumps of the NM series.
Progressing cavity pumps power train
Another component in constructing the progressing cavity pump is the so-called power train. It consists of a coupling rod and two cardan joints for transmitting power from the drive to the rotor. We also offer patented, open hygienic joints without dead space, which allow optimal cleaning for the food industry. NETZSCH has developed an FSIP® (Full Service In Place) model for easy maintenance and servicing. This will enable you to remove the complete power train from the pipeline without first removing the progressing cavity pump. By removing the inspection cover of the FSIP® pump, you gain access to a cup coupling that connects the joint on the rotor to the coupling rod. Here it is sufficient to loosen a screw to separate the two elements. The innovative construction of the progressing cavity pump in FSIP® design saves you time and, therefore, money in maintenance and servicing.
Shaft sealing of the progressing cavity pump
The shaft seal is another critical component in the design of the progressing cavity pump. A single-acting, wear-resistant mechanical seal independent of the direction of rotation is installed as standard. Mechanical seals are dynamic seals that close off the rotating shaft from the pump housing. We also offer single/double mechanical seals of various designs and manufacturers, cartridges and special seals, and stuffing box packings for special applications. With the progressing cavity pump in FSIP® design, the shaft seal can easily be changed through the inspection opening. In addition, there are shaft seals with a pressure-proof screwed seal housing, especially for the hygienic sector, which allows you to reverse the direction of rotation up to the maximum pump pressure. Nothing stands in the way of safe and reliable pumping.
Progressing cavity pumps suction and discharge casing
Another component in constructing the progressing cavity pump is the suction and discharge casing. This can be connected to your system or pipeline with flanges or threaded connections by DIN and international standards. It is made of grey cast iron, steel, chrome-nickel steel with rubber coating or unique materials according to your requirements. In the case of the progressing cavity pump in FSIP® design, the design of the suction casing differs from the standard container due to the large inspection cover. However, the dimensions remain the same. This means that the pump can be serviced on-site. All parts in contact with the medium are immediately accessible without dismantling the piping and drive. This means that the wearing parts can be changed in less than half. Any NEMO® BY pump already installed can be retrofitted.
Drive of the progressing cavity pump
A categorisation is made between two different types for the drive of the progressing cavity pumps from NETZSCH - the block design and the design with bearing bracket and free shaft end. The drive flanged directly to the lantern in the construction of the progressing cavity pump in block design results in compact dimensions, low total weight, constant shaft heights independent of the construction and size of the drive, low maintenance costs and serviceability. With a progressing cavity pump in bearing bracket design, on the other hand, universal use of all drive types is possible.
Due to their unique design, progressing cavity pumps cover a wide range of applications in all branches of industry. In addition to the continuous, pressure-stable, gentle and low-pulsation delivery of even the most demanding media, the progressing cavity pump enables you to dose in proportion to the speed.