Canned rotor pumps are Glandless Pumps whose rotating components within the canned motor run in the liquid being handled by the pump.

Design
Shaft sealing by means of a stuffing box or a mechanical seal required for conventional pumps thus becomes obsolete. The pumped liquid serves as a lubricant for the bearings (sleeve bearings) and as a coolant to the motor compartment. A can serves to seal the so-called wet space to atmosphere and to the motor compartment. The can, of a mean wall thickness of only 0.1 to 0.3 mm, is made of magnetic highly alloyed steel. Generally, the can is statically sealed by means of O-rings.

Funktion / Feature
The advantage of this construction is primarily the totally maintenance-free operation. No alignment or dis-mantling of sealing components but a reliable and faultfree run operation during the entire operation.

The quietness of operation of this design is remarkable, this being due to the dampening effect of the water in which the rotating parts move and, most particularly, to the sleeve bearing support of the rotor. Thus any noise normally originating from ball or roller bearings are fully eliminated .
Not only the quiet operation but also the service life span and the defect susceptibility are decisively influ-enced by this component.

The bearing arrangement is one of the essential constructional features of canned rotor pumps. The mate-rial combination of the bearings is, apart from the actual design of the bearings, of decisive importance for the operational reliability of the pump. The following combinations have eventually prevailed in practice:

• ceramic shaft/ceramic bearing
• hardened stainless steel shaft/carbon bearings