A lobe pump is positive displacement pump that features a pair of lobed rotors that revolve within a sealed, close-fitting casing. The rotors usually have three lobes each and mesh in a similar fashion to gears, although direct contact between them is prevented. The lobes' outer edges also pass in very close proximity to the inner surface of the casing. In this way, the rotors form sealed pockets between their lobes and the casing as they revolve, which transports material from the pump inlet on the one side of the casing to the outlet on the other. Lobe pumps are used in many industries that require a gentle, non-destructive pumping action, and may be used to pump solids, suspensions, and certain fluids.
Lobe pumps operate in a similar fashion to gear pumps in that they transport the pumped material around an enclosed casing trapped in cells or pockets formed between protrusions on rotating hubs. In the case of a lobe pump, there are two hubs or rotors located within a close-fitting, closed casing. The lobe pump rotors typically feature three equally-spaced protrusions or lobes, which resemble a clover leaf when viewed straight on. The rotors turn in opposite directions and are positioned in such a way that their lobes mesh, but do not actually make physical contact with each other. In other words, while rotating, the lobe on one rotor will pass through the space between two of the other rotor lobes without touching them.
The gap between the rotor lobes and the pump casing is also very small, which means that the spaces between the lobes form sealed cells as they pass the pump casing. It is this feature that facilitates the transport of the material being pumped. As the rotors turn, they draw material through an inlet port on one side of the casing, and trap it in the gaps between the lobes where it follows the rotor movement around the casing before being discharged from the outlet port on the opposite side.
These pump types are known for their gentle action that has very little abrasive or concussive effect on the material passing through it. For this reason, the lobe pump is often used in industries where sensitive materials are pumped. The lobe pump is also very flexible in the range of materials for which it may be used. It can be used to move solids, such as small fruits; suspensions; and certain fluids, particularly those with a high viscosity such as oils.