Internal Gear pump with see-through head

Understanding Internal Gear Pumps: How They Work and Their Benefits

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by John Hall - Pump Consultant
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Discover how internal gear pumps work, their key features, and their advantages across various industries. Learn why they're the preferred choice for fluid handling.

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Case Study
Industrial
Pump Technologies
Pumping Principles

Introduction to Internal Gear Pumps

Internal gear pumps are a fascinating invention that has stood the test of time. Created by Viking Pump over a century ago, they remain one of the company's most recognized products. These pumps are a type of rotary positive displacement pump, which means they move fluid by utilizing the rotary motion of their components.

Vane Pump

A type of rotary positive displacement pump consisting of a slotted rotor offset in a cam shaped housing. Sliding vanes in the slots of the rotor extend to create pumping cavities, sweep the liquid through the casing, and expel the liquid at the discharge side of the pump as the cam reduces in area and forces each vane back into its slot. Click here to view our How it Works video on this topic

Air Operated Double Diaphragm

A type of pump featuring a pair of opposing diaphragms alternatively expanded by compressed air to expel liquid on the opposite side of the diaphragm. An air valve in the pump shifts the flow of air from one diaphragm to the other resulting in an intake stroke on one side and a discharge stroke on the other. Check valves in the pump prevent the backflow of pumped liquid.

Circumferential Piston Pump

A type of rotary positive displacement pump consisting of a pair of externally timed rotors such that each is driven independently and the rotors are non-contacting. Rotor designs vary but the most common type is bi-wing. Similar in operation to a lobe pump. Click here to view the Pump Report on this subject. 

Lobe Pump

A type of rotary positive displacement pump consisting of a pair of externally timed rotors such that each is driven independently and the rotors are non-contacting. Rotor designs vary but some of the more common types include bi-wing (or scimitar), tri-lobe, and various multilobe designs. Similar in operation to a circumferential piston pump. Click here to view our How it Works video on this topic.

Gear Pump

Any type of rotary positive displacement pump consisting of gears where the pumping results from the unmeshing and remeshing of gears. The liquid is carried between the gear teeth by the rotation of the pump. Common types of gear pumps include internal gear, external gear, and gerotor.

External Gear Pump

A type of gear pump featuring two identical external gears where one gear is the drive gear and one is the driven. The liquid is transferred from between the gear teeth by the rotation of the pump. Click here to view the Pump Report on this subject. 

Internal Gear Pump

A type of gear pump a drive gear featuring inward facing teeth called a rotor. This rotor turns an offset gear with fewer outward facing teeth called an idler. A crescent shape protruding from the head of the pump creates this offset and seals the pumping cavities formed between the gear teeth. Click here to view our How it Works video on this subject. 
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