The impeller is one of the most important parts of your centrifugal pump. Depending on your application, impeller selection can be crucial to pump performance. Slurry applications can be especially hard on the impeller of your pump because of their abrasive nature. In order for your process to operate efficiently and stand up to the test of time, you must choose the proper impeller.
There are three different types of impellers; open, closed, and semi-closed. Each has its own strengths and weaknesses, depending on the application. Some are better for solids handling, others are better for high efficiency. To learn more about the specifics of each type of impeller, read our blog post that explains the difference between them.
Any type of impeller can be used in slurry applications, but open impellers are more common because they are less likely to clog. Closed impellers usually don’t do well with solids and are difficult to clean if they become clogged. For example, the small fibers in paper stock which, in high densities, may have a tendency to clog the impeller. Pumping slurry can be difficult and you want to avoid a clogged pump at all costs.
The size of the pump’s impeller must be considered to ensure it holds up against abrasive wear. Slurry impellers are generally larger in size when compared to pumps for less abrasive liquids. The more “meat” the impeller has, the better it will hold up to the task of pumping harsh slurry mixtures. Think of the pump’s impeller as a football team’s offensive line. These players are usually large and slow. Throughout the whole game they are beaten up, over and over again, but expected to withstand the abuse. You wouldn’t want small players in this position, just like you wouldn’t want a small impeller on your slurry pump.
Your process speed doesn’t have anything to do with choosing your impeller, but it does have an effect on the life of your impeller. It is important to find the sweet spot that allows the pump to run as slow as possible, but fast enough to keep solids from settling and clogging. If you are pumping too fast, the slurry can quickly erode the impeller due to its abrasive nature. This is why it is important to select a larger impeller if possible.
When you’re dealing with slurry, you generally want to go bigger and slower. The thicker the impeller, the better it will hold up. The slower the pump, the less erosion you’ll inflict on the impeller. However, the impeller isn’t the only thing you have to worry in your pump when dealing with slurry. Tough, durable materials of construction are necessary most of the time. Metal liners and wear plates are common in slurry applications. Read our beginner’s guide to pumping slurry for more information.
If you have questions about pumping slurry or need a pump sized for your slurry application, contact us! Our engineers are ready to help businesses in the Wisconsin and Upper Michigan area.