Lobe pumps are positive displacement pumps that use rotating lobes to direct flow. Lobe pumps are similar to gear pumps in operation in that fluid flows around the interior of the casing. However, because of the unique rotating lobe configuration, lobe pumps can reduce the shear effects commonly associated with gear pumps, and unlike gear pumps, the lobes do not make contact as the external timing gears located in the gearbox prevent this. The lobes on the rotating elements of lobe pumps foster the ability to drive large solids and slurry-laden media. Pumps are available in double or triple lobe configurations. The number of lobes on each rotating element determines this number.
The determination of which style is better for a given application depends upon the solids size, liquid viscosity, and tolerance of flow pulsation. Two lobes tend to handle larger solids and high viscosity but pulsates more than three lobed elements. Lobe pumps are frequently used in food applications because they can process solids without damaging the product. Since the lobes do not contact each other, these pumps can handle products of a larger particle size and are ideal for pushing through low viscosity media. In fact, they may be among the best positive displacement (PD) pumps for this type of application. However, lobe pumps are not well suited for transporting higher viscosity liquids as their design can lead to foaming and reduced lift unless they are run at a lower speed than their normal rating. Lobe pumps are used in a variety of industries including, pulp and paper, chemical, food, beverage, pharmaceutical, and biotechnology.
They are popular in these diverse industries because they offer superb sanitary qualities, high efficiency, reliability, corrosion resistance, and good clean-in-place and service-in-place (CIP/SIP) characteristics. Their design also eliminates any metal-to-metal contact, which can help to cut down on impurities within passed media. However, lobe pumps do require a fair bit of service as they require two sets of timing gears and two seals, all of which have a tendency to wear during use.