Design
The uniform feature of glanded pumps is the separation between the pumped fluid and theirst drive motor. The connection between the impeller in the pump body and the motor is made by either a common shaft or by coupled shaft parts. The rotating motor component remains dry (thus the term Dry-Motor Pump). The rotor support by means of roller bearings requires separate lubrication. The pumps are normally driven by IEC-standards electric motors but also by special design motors up to explosion-protected versions.
Pump types / function
Glanded pumps are of two distinctly different designs:
- Monobloc Glanded Centrifugal Pumps
- DIN-Standards Centrifugal End-Suction Pumps
Glanded pumps are louder than glandless pumps. The noise is caused by the roller bearing (ball bearing or needle bearing) and the fan wheel of the surface-cooled electric motor. The noise of the pump itself – flow noise, bearing noise – is completely negligible, unless unusual operating situations occur (cavitation, etc.).
There are two distinctive designs of glandless pumps, one with dry stator windings (Canned Rotor Motor) and one with wet-stator windings (Wet Stator Motor).
With this design, there is no shaft seal between the pump and the motor. The pumped medium is used for cooling and lubricating the motor at the same time. Glandless pumps are considered to be particularly low-noise, which makes them ideal for use in living spaces. The omission of the shaft seal makes the system particularly low-maintenance and leakage-free. This also makes canned motor pumps interesting in process technology for applications where leakage-free pumping is important.
A disadvantage is the lower efficiency compared to pumps with shaft seals (glanded pumps), especially at higher outputs.
Typical applications for canned rotor pumps are as heating circulating pumps, process pumps for the chemical industry and process engineering and as nuclear reactor pumps. Wet stator pumps are mainly used as submersible pumps in wells and for circulating duties in conventional power plants.
