Types of Pump Impellers and How They Work

Industrial Pump Products and Services
/
/
Types of Pump Impellers and How They Work
Industrial Pump Products and Services
Types of Pump Impellers and How They Work

Types of Pump Impellers and How They Work

In Pump Terminology

Pump Impellers: Types and How They Impact Pump Performance

Pump impellers are vital for transferring motor energy into the fluid being pumped. There are three main types of pump impellers: closed, semi-open, and open. While each design brings unique benefits, selecting the right impeller depends on factors like the fluid being pumped, NPSHa (Net Positive Suction Head Available), and required head pressure. The impeller design also affects the pump curve and the Best Efficiency Point (BEP) of the pump. With this in mind, let’s dive into the three different centrifugal pump impeller types.

 

Pump Impeller Types

1. Closed Pump Impellers

Closed pump impellers feature vanes fully enclosed by back plates. This design prevents fluid from bypassing the vanes thus leading to higher efficiency and pressure output. These impellers are ideal for applications involving high-viscosity liquids, such as oils, or when high pressure is required. They work particularly well for water boosting applications in water and wastewater treatment facilities.

A closed pump impeller with vanes enclosed by surrounding rings, designed to prevent fluid bypass for improved efficiency and higher pressure output.
  • Pros: Higher efficiency, better pressure output.
  • Best for: High-viscosity liquids, pressure-sensitive applications.

2. Semi-Open Pump Impellers

Semi-open pump impellers have partially enclosed vanes, balancing the performance of open and closed impellers. This type offers flexibility, making it a suitable option for applications that require the benefits of both designs. If your fluid has too many free particles for a close impeller, then switch to a semi-open impeller. If you need more pressure or feet of head with an open impeller, switch to a semi-open impeller.

A semi-open pump impeller with partially enclosed vanes, offering a balance between performance and fluid handling, suitable for various applications.
  • Pros: Balance between open and closed designs, good for flexible applications.
  • Best for: Versatile applications with moderate pressure and fluid types.

3. Open Pump Impellers

Open impellers allow for large amounts of suspended solids to pass through because the vanes are not attached to a plate. This allows for free flowing particles to easily pass through the volute and leave via the outlet. Open pump impellers excel at pumping slurries and solids laden liquids, but it comes at a cost to efficiency and durability.  

An open pump impeller with vanes exposed, commonly used in applications where fluid is less viscous or where handling solids is necessary.
  • Pros: Able to pump a high amount of solids and heavy slurries.
  • Best for: Paper stock pumps and mining applications with heavy slurry.

Choosing the Right Pump Impeller for Your Application

Choosing the right impeller design can ensures optimal pump performance. Consider factors like fluid type, system pressure, and NPSHa when making your selection. For expert advice, consult with pump specialists who can assess your system’s needs and recommend the best impeller for your application.

Conclusion

Understanding the different types of pump impellers — closed, semi-open, and open — and their unique applications can help you choose the right design for your pump system. Each impeller design offers distinct advantages, and understanding how they affect performance is key to achieving the desired outcomes in your system.