Gear Pumps

Gear pumps operate by an unchanging volume of fluid passing between the teeth of two meshing gears and their casing at a constant rate (not between the gears themselves). As the gears rotate and the meshed teeth separate, a partial vacuum is formed that fills with fluid, which they trap and move it around the casing from the suction to the discharge point.

The pumping of high viscosity lubricating fluids such as oils, fuels, paints, soaps and resins. The pumping of low viscosity fluids should be avoided as they can cause fluid to leak backwards or "slip" back to the suction side.

An external gear pump has two identical gears positioned side by side, rotating and interlocking into one another. One is driven by the motor and in turn moves the other gear.

An internal gear pump operates a "gear within a gear" principle, whereby one gear (the idler) is positioned inside another gear (the rotor).

Whilst external gear pumps offer higher pressure and flow rates, internal gear pumps generally have better suction capabilities and are able to handle higher temperature, higher viscosity fluids. Internal gear pumps slower speeds and larger clearances also makes them more suitable for shear sensitive fluids

Yes. Gear pumps have excellent self-priming capabilities thanks to their rotating gears evacuating any air in the suction line, and forcing the liquid into the pump inlet.

The close tolerances between the gears and casing mean that pumping solids will result in wear and damage. Some internal gear pump designs which have less tight tolerances and slower speeds however may be able to tolerate small solids.