Features

Understanding internal gear pumps: How they work and their benefits

John Hall, Pump Consultant at Viking Pump, a brand distributed in the UK by Michael Smith Engineers, explains the features and benefits of internal gear pumps, exploring the applications to which they are suited and the key considerations that should be made as part of their selection.

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 recognised products.

Internal gear pumps are a type of rotary positive displacement pump, which means they move fluid by utilising the rotary motion of their components.

How internal gear pumps function

The operation of an internal gear pump is based on a simple yet effective principle. Liquid enters through the suction port, which is positioned between the teeth of the rotor gear (the larger external gear) and the idler gear (the smaller internal gear).

The interaction between these intermeshing gears creates locked cavities that hold the liquid, ensuring precise volume control. As the gears turn, they create low-pressure zones at the suction port. This low pressure pulls liquid into the pump, where it continues to travel between the teeth of the gears.

A key component in this process is the crescent located at the head of the pump. This crescent acts as a seal, preventing the liquid from returning to the suction side. When the gear teeth mesh completely, the liquid is forced out of the pump through the discharge port.

This design allows internal gear pumps to handle a wide range of viscosities, making them ideal for various applications.

Key Features

Understanding the features of internal gear pumps helps highlight their advantages. Here are some of the critical aspects:

  • Rotary Motion: The rotary movement of the gears enables the pump to draw in and discharge liquid efficiently.
  • Volume Control: The intermeshing gears create locked cavities that ensure consistent volume control of the liquid being pumped.
  • Low Pressure Zones: As the gears turn and come out of mesh, they create low-pressure areas that pull liquid into the pump.
  • Crescent Seal: The crescent effectively seals off the suction side from the discharge side, preventing backflow.
  • Versatility: The internal gear design allows these pumps to manage a variety of liquid viscosities, from thin solvents to thick oils.

Advantages

Internal gear pumps offer several advantages that make them a preferred choice in many industries. Here are some key benefits:

  • High efficiency: The design of internal gear pumps ensures a consistent flow rate, regardless of changes in pressure, which translates to minimal energy wastage.
  • Self-priming: These pumps can seamlessly evacuate air or gas from the suction line, ensuring uninterrupted operation.
  • Robust construction: Built with quality in mind, internal gear pumps are designed for longevity and reliability, even in challenging environments.
  • Wide viscosity range: They can handle thin liquids like solvents as well as thick substances like molasses, making them versatile for different applications.
  • Quiet operation: The gear design allows for smooth and silent operation, creating a more comfortable working environment.
  • Precise flow control: Operators can easily adjust the flow rate by changing the rotational speed, which is crucial for accurate dosing and product quality.
  • Low maintenance: With fewer moving parts, the likelihood of breakdowns is reduced, leading to lower maintenance costs.

Applications

Due to their unique features and advantages, internal gear pumps are widely used across various industries. In chemical processing, they are ideal for handling various chemicals, including corrosive and viscous materials. In the food and beverage sector, internal gear pumps can handle thick and viscous liquids. The precision and reliability of these pumps also make them suitable for the pharmaceutical industry, where accuracy is crucial. Internal gear pumps are often utilised in oil and gas applications for moving crude oil and other viscous fluids, and they can efficiently handle the thick slurries found in pulp and paper production.

Choosing the right internal gear pump

Selecting the right internal gear pump for your application involves considering several factors. First, it is important that the pump can handle the specific viscosity of the liquid in which it is intended to move. The flow rate required for your process should be determined, and a pump that meets this demand should be selected. The temperature range of the fluid should be assessed so a pump designed to operate within that range can be chosen. Consideration should also be given to the materials used in the pump construction to ensure they are compatible with the fluids being pumped. And it is advisable to look for a pump that offers ease of maintenance to minimise downtime.

Conclusion

Internal gear pumps provide efficient and reliable fluid transfer solutions across various industries. Their unique design allows them to handle a broad spectrum of viscosities while maintaining consistent performance. By understanding how these pumps work and their advantages, businesses can make informed decisions when selecting the right pumping solution for their needs.

www.michael-smith-engineers.co.uk

www.vikingpump.com

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