Gear pumps rely on two meshing gears to cause liquid flow. They are precision machines with extremely tight fits and tolerances, and are capable of working against high differential pressures. They come in two types: two gears with external teeth or one gear with external teeth within another with internal teeth.
The most common uses for gear pumps are to move chemical and petrochemical liquids that have relatively high viscosity; to supply fuel oil for burners or other facilities; and to transfer gasoline, kerosene, fuel oil and diesel oil. They also feature in hydraulic devices such as actuators, damper controls and elevators. In addition, they pump coolants, paints, bleaches, solvents, syrups, glues, greases, asphalt, petroleum and lubrication oils, and handle many general industrial applications.
Gear pumps, when properly designed and engineered, can offer many advantages. These include compactness, simplicity, easy serviceability, bidirectional and pulseless flow, self-priming, low net positive suction head requirement, high mean time between maintenance, high-pressure and high-temperature capability, precise and accurate metering, and availability in multiple seal configurations or with sealless magnetic drives.