The successful combination of high-quality slide bearings and comprehensive axial thrust balancing demonstrates the quest for absolute precision. This results in HERMETIC canned motor pumps running without contact and wear. Manufactured and tested to the highest quality standards in the factory, HERMETIC pumps guarantee long service life (MTBF) when used properly. Systems integrated into the pump, such as the MAP, monitor the position of the rotor and thus the axial thrust balancing. This ensures reliable operation of the entire system.
Axial thrust is a challenge that must be met in almost all centrifugal pumps. The pump shaft is drawn in the direction of the suction side due to the pressure difference between the pressure and suction side. For example, bearings must absorb the resulting forces. Slide bearings are used in hermetically sealed pumps, such as magnet-coupled or canned motor pumps. This leads to specific requirements for axial thrust balancing.
The specific properties of the media that requires conveying exclude the use of mechanical thrust bearings in hermetically sealed pumps. Axial thrust balancing can therefore only be achieved by the hydraulic balancing of the rotor.
In HERMETIC canned motor pumps, the axial position of the pump shaft is controlled automatically during operation. The applied technology automatically creates a powerless state of equilibrium. No axial forces act on the thrust bearing collar of the slide bearings. A thin liquid film with high load-bearing capacity similar to aquaplaning between the rotating and the static part of the slide bearing causes the entire rotor to float.
This state of equilibrium, the so-called HERMETIC ZART® principle (Zero Axial and Radial Thrust), results from the fact that there is no contact between the rotating and stationary components. The non-contact running leads to wear-free normal operation with much longer service life (MTBF) compared to other designs.
The technical design of axial thrust balancing depends on the size, number of stages and the medium to be conveyed of each pump used.