Gear pumps are a type of positive displacement pump which use rotating cogs or gears for transferring fluids. They are available as either internal gear pumps or external gear pumps, and they each have different applications. External gear pumps use two identical interlocking gears, which are supported by separate shafts. In most cases, one gear is driven by a motor, and this drives the other gear; however, some external gear pumps have two shafts driven by motors. These types of pumps are used across many industries for many different reasons. We are looking at where external gear pumps are used and what their main applications are.

External Gear Pump Applications

The most common place you will find external gear pumps is in any application that requires water pumping. Flood water, rainwater, firefighter water, and many more often use external gear pumps to move the liquid from one place to another. It isn’t just water that these pumps are great for, but any kind of light oil, resins, solvents or chemical additives. External gear pumps are great for applications that require accurate dosing. This includes fuels, chemical additives or polymers. You will usually find external gear pumps being used for:

  • Water
  • Fuel oils and lube oils, including engines and gearboxes
  • Chemical mixing or blending
  • Agricultural, industrial and mobile hydraulic applications including log splitters, forklifts and tractors
  • Acids and caustic
  • Solvents
  • Alcohol
  • Resins and polymers

Where Can External Gear Pumps Not Be Used?

External gear pumps can self-prime and require lubrication from the pumped fluid. There are very close tolerances between the casing and the gears, making external gear pumps not suitable for abrasive liquids. Internal gear pumps are much better at handling abrasive fluids because they have only one bearing running in the liquid. Fluids such as paint, soaps and foodstuffs are not ideal for use in external gear pumps because of the high speeds and small clearances.

It is also essential that users are careful with high-temperature liquids in external gear pumps. Some pumps are designed to handle high temperatures, but others are not, and it can result in pump failure. When a high-temperature fluid is used in an external gear pump, it can cause the gears and casing to expand and reduce the clearances within the pump.

To discuss your requirements and find out which external gear pumps are best for your application, speak with our team of specialists today.

Applied Pumps Limited Request a call back from a pump expert