A lobe pump, or rotary lobe pump, is a type of

positive displacement pump A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy. Pumps can be classified into three major groups according to the method they ...

. It is similar to a gear pump except the lobes are designed to almost meet, rather than touch and turn each other. An early example of a lobe pump is the Roots Blower, patented in 1860Stahl Electromach: Roots Blower
/ref> to blow combustion air to melt iron in blast furnaces, but now more commonly used as an engine supercharger. Lobe pumps are used in a variety of industries including

pulp and paper The pulp and paper industry comprises companies that use wood as raw material and produce pulp, paper, paperboard and other cellulose-based products. Manufacturing process The pulp is fed to a paper machine where it is formed as a paper web a ...

chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., w ...

food Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is in ...

beverage A drink or beverage is a liquid intended for human consumption. In addition to their basic function of satisfying thirst, drinks play important roles in human culture. Common types of drinks include plain drinking water, milk, juice, smoo ...

pharmaceutical A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and ...

, and

biotechnology Biotechnology is the integration of natural sciences and engineering sciences in order to achieve the application of organisms, cells, parts thereof and molecular analogues for products and services. The term ''biotechnology'' was first used ...

. They are popular in these diverse industries because they offer superb sanitary qualities, high efficiency, reliability, corrosion resistance and good clean-in-place and steam-in-place (CIP/SIP) characteristics. Rotary pumps can handle solids (e.g.,

cherries A cherry is the fruit of many plants of the genus '' Prunus'', and is a fleshy drupe (stone fruit). Commercial cherries are obtained from cultivars of several species, such as the sweet ''Prunus avium'' and the sour ''Prunus cerasus''. The ...

and

olives The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' 'M ...

), slurries, pastes, and a variety of liquids. If wetted, they offer self-priming performance. A gentle pumping action minimizes product degradation. They also offer continuous and intermittent reversible flows and can operate dry for brief periods of time. Flow is relatively independent of changes in process pressure, too, so output is relatively constant and continuous.

Function

Lobe pumps are similar to external gear pumps in operation in that fluid flows around the interior of the casing. Unlike external gear pumps, however, the lobes do not make contact. Lobe contact is prevented by external timing gears located in the

gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), diff ...

. Pump shaft support bearings are located in the gearbox, and since the bearings are out of the pumped liquid, pressure is limited by bearing location and shaft deflection which reduces the noise levels of this pump. Lobe pump is one of the Positive Displacement Pump rotary type. 1. As the lobes come out of mesh, they create an expanding volume on the inlet side of the pump. Material to be pumped (liquid, or gas, possibly containing small solid particles) flows into this cavity. Rotation of the lobes past the inlet port creates enclosed volumes of material between the rotors and the pump casing. 2. The material travels around the interior of the casing in these enclosed volumes between the rotor's lobes and the casing — it does not pass between the lobes. 3. Finally, the meshing of the lobes on the discharge side of the pump prevents the pumped material from returning to the inlet side. Continued pumping forces the pumped material out through the outlet port. If the discharge port is restricted - such as discharging a large volume of air into an engine's intake manifold - then pressure is created in the discharge space. A lobe pump itself does not compress the material it pumps. Lobe pumps are frequently used in food applications because they handle solids without damaging the product. Particle size pumped can be much larger in lobe pumps than in other positive displacement types. Since the lobes do not make contact, and clearances are not as close as in other Positive displacement pumps, this design handles low

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the int ...

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.

References

External links

PumpSchool.com Lobe Pump entry

{{Authority control Pumps

Function

See also

References

External links