Lobe Pump – Working , Advantages , Disadvantages , Application
Lobe Pump – Construction
The operation of lobe pump shown in Fig. is similar to that of external gear pump, but they generally have a higher volumetric capacity per revolution. The output may be slightly greater pulsation because of the smaller number of meshing elements.
Lobe pumps, unlike external gear pumps,have both elements externally driven and neither element has any contact with the other.For this reason, they are quieter when compared to other types of gear pumps. Lobe contact is prevented by external timing gears located in the
gearbox.Pump shaft support bearings are located in the gearbox, and because the bearings are out of the pumped liquid, pressure is limited by bearing location and shaft deflection. They do not lose efficiency with use. They are similar to external gear pumps with respect to the
feature of reversibility.
Lobe Pump Diagram :
Working Of Lobe Pump :
1.As the lobes come out of mesh, they create expanding volume on the inlet side of the pump.Liquid flows into the cavity and is trapped by the lobes as they rotate.
2.Liquid travels around the interior of the casing in pockets between the lobes and the casing (it does not pass between the lobes).
3.Finally, the meshing of the lobes forces the liquid through the outlet port under pressure. Lobe pumps are frequently used in food applications because they are good at handling solids without inflicting damage to the product. Solid particle size can be much larger in lobe pumps than in other positive displacement types.Because lobes do not make contact, and clearances are not as close as in other positive displacement pumps, this design handles low viscosity liquids with diminished performance.Loading characteristics are not as good as other designs and suction ability is low.High-viscosity liquids require reduced speeds to achieve satisfactory performance.Reductions of 25% of rated speed and lower are common with high-viscosity liquids.
Advantages Of Lobe Pump
The advantages of lobe pumps are as follows:
1. Lobe pumps can handle solids, slurries, pastes and many liquid.
2. No metal-to-metal contact.
3. Superior CIP(Cleaning in Place) /SIP(Sterilization in Place) capabilities.
4. Long-term dry run (with lubrication to seals).
5. Non-pulsating discharge.
Disadvantages Of Lobe Pump
The disadvantages of lobe pumps are as follows:
1. Require timing gears.
2. Require two seals.
3. Reduced lift with thin liquids.
Applications Of Lobe Pump
Common rotary lobe pump applications include, but are not limited to, the following:
2. Paper coatings.
3. Soaps and surfactants.
4. Paints and dyes.
5. Rubber and adhesives.
7. Food applications.
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