Normal centrifugal pumps require a certain fill level so that they can convey the medium free from air – and therefore free from faults. In flat chip conveyors, however, a low fill level usually prevails so that special self-priming centrifugal pumps that vent themselves can be used there.
If the liquid that is to be conveyed is a cooling lubricant, an additional difficulty arises for the pump. Even if a filter with a fineness of less than 1/10 mm is connected upstream, a low chip freight remains in the emulsion or oil, which can cause damage to the pump in just a short time.
KNOLL Maschinenbau therefore developed the BS 40 – their own self-priming centrifugal pump that is ideal for the application described here. It stands out thanks to its short venting time and particularly robust materials. The conveying volume flow is between 140 and 320 l/min, and the pressure is max. 2 bar.
The developers of the BS 40 paid great attention to the axial face seal, which is at particular risk of wear. On the one hand, the material is significantly more resistant than on conventional seals for standard water pumps. On the other hand, it is constructed in such a way that a maintenance employee can quickly and easily replace it.
As for most of their pumps, for the BS 40, KNOLL also recommends operation with a frequency inverter that regulates the liquid to a pre-set level. This prevents start-stop operation of the pump, protects the components (especially the axial face seal), and ensures great energy efficiency since choke losses are avoided.
The modular system that is preferred by KNOLL is also used for the BS 40. As is the case with all centrifugal pumps, the same frequency inverter and the global engines that are configured jointly with Siemens are always available directly from stock. Other components, such as pipes and bearings, are also identical across all designs of KNOLL centrifugal pumps.
During the new development of the BS 40, the KNOLL developers also paid close attention to small but useful details. This meant that they were able to include space in the pump lantern for a leakage sensor. If this option is used, the sensor indicates damage to the seal even before a puddle of oil or emulsion forms below the pump.
KNOLL Maschinenbau at AMB 2018 in Hall 8, booth C 40.