Igensättning av övre spalten i centrifugalpump
This report focuses on the upper slit. The upper slit is located between the impeller andthe drive unit. The slit design depends on pump type and application. However it isuncertain why the design varies, The purpose of this report is to clarify why the designvaries and to recommend an improved slit design.A research has been done; information was gathered from interviews, but also fromsearching of databases and studies of drawings, reports and documents. The originalpurpose of the slit was to prevent twining around the driveshaft, and prevent dirt fromentering the cooling system. Nowadays external cooling system is only used on largepumps. The system filters the pumped medium through the thin slit to prevent cloggingof the cooling pipes and uses it to cool the motor unit. Generally most pumps workexcellent in their applications, but one specific application causes problems; small andmid-range pumps are sometimes used on farms to mix and transport manure. Manurecontains short fibers which easily get stuck behind the slit on top of the impeller. Theamount of fibers increases until the rotation of the impeller is disturbed or the sealingmalfunctions.Two concepts are recommended for further development. They are called ?Vågen? (?TheWave?) and ?Tätningshylsan? (?The Sealing Cartridge?). Vågen has got two waveshaped flanges that together form the slit. This design makes the slit both open and closedby turns, as the impeller rotates. The theory is that long fibers will not pass the slitalthough it will be open enough not to trap short fibers. In Tätningshylsan, by moving thecartridge as close as possible to the driveshaft, the braking effect of packed fibers on theinside of the slit is minimized. The smaller radius also causes long fibers to pass thecartridge rather than twine around it. The seal is meant to stop fibers from passingthrough the slit.