Since it is difficult to reduce the tolerance between the lobes and the housing due to manufacturing process limitations, one of the biggest disadvantages of lobe pumps is the presence of a backflow gap. This results in a reduction in the maximum outlet pressure. For this reason, the volumetric efficiency of lobe pumps is lower than that of other pump types such as centrifugal or axial pumps.
Additionally, the significant leakage caused by this void space reduces the pump’s efficiency in low-viscosity fluids. Although this reduction is not so great as to make these types of pumps unsuitable for fluids such as water, their efficiency will be significantly lower.
Another disadvantage of lobe pumps is the need for components such as timing gears, which most conventional pumps do not require. These components greatly increase the final cost of the pump, and the gears themselves cause energy loss and reduce the overall efficiency of the pump. The maintenance costs of these components will also add to the total cost of the system.
The two-stage sealing in these types of pumps also complicates the manufacturing process and increases production costs. In general, earring pumps have a relatively high initial cost to the buyer.
