What's The Difference Between Open, Semi-Open, and Closed Impellers?

Centrifugal pump impellers are selected with purpose and are dependent upon the application. Some are better for solids handling, others are better for high efficiency. Read on to find out which impeller will be best for your centrifugal pump application. 

Open Impeller

An open impeller has vanes that are attached to a center hub and mounted directly onto a shaft. There is no wall surrounding the vanes which makes open impellers weaker than closed or semi-closed valves. 

Open impellers are generally faster and easier to clean and repair.  Open impellers are usually used in smaller pumps and pumps that handle suspended solids. 

Semi-Closed Impeller

Semi-Closed impellers have a back wall that adds strength to the impeller.  Semi-closed impellers are usually used with liquids or products that have solids. Reduced efficiency is a common problem with semi-closed impellers, but the ability to pass solids is an important trade-off. 

Closed Impellers

Closed impellers have a back and front wall around the vanes, to increase strength.  Closed impellers are used primarily in larger pumps and can be used in applications that handle suspended-solid service.

These types of impellers are commonly found in clear liquid applications. They don't do well with solids and are difficult to clean if they become clogged. 

Still not sure which impeller will be best for your next pumping application? Be sure to check wtih an application engineer who is well versed in pumps and selection best practices.

Get help with your next pump selection now!We gladly provide technical assistance to businesses and municipalities in Wisconsin and upper Michigan.