In this article, we explore the complete selection guide of an impeller from “define impeller”, its types, strengths and weaknesses. Also, its applications, how it is used in centrifugal pumps. Furthermore, how to choose the right impeller, its diameter, and the overall impact of the impeller has been discussed. Last but not the least, frequently asked questions have been added to understand this topic easily.

What is an Impeller?

Meaning: When it comes to pumping fluids, an impeller meaning is an essential component of centrifugal pumps. It performs the primary function of converting the mechanical energy from the motor to kinetic energy. This energy increases the fluid’s pressure and flow rate. water pump impeller An impeller pump is a rotating disk with curved blades that create a vacuum. This then pulls the fluid into the center and propels it outwards. The rotation speed is key. Knowing what an impeller is and its different types is crucial because it determines the pump’s performance and efficiency. Choosing the right impeller for a specific application can maximize flow rates, minimize energy consumption, reduce downtime, and save money.

Get in touch with us

How is it used in a Centrifugal Pump?

Centrifugal Pump The impeller of a centrifugal pump is the most crucial part. The pump’s motor rotates the impeller at high speeds. This generates a centrifugal force that moves the fluid outwards, creating a low-pressure area in the center of the impeller. The low-pressure area then draws in more fluid from the suction line. The cycle continues, creating a continuous flow of fluid. The flow pattern needs to be measured.

Impeller Types and Uses:

 These include open, closed, semi-open, recessed, and vortex impellers. The impeller types differ in their blade shape, size, and orientation, and each type is suitable for specific applications.

Open Impellers:

Open Impeller Definition An open impeller has vanes attached to a central hub without a shroud or cover. They are used for pumping low-viscosity fluids without suspended solids and are easy to clean and maintain. Uses They are commonly used in chemical processing, water treatment, and food industries. Strengths and weakness | Advantages and disadvantages One strength of open impellers is that they are easy to manufacture. But a weakness is that they have lower efficiency compared to other types.

Closed Impellers:

Closed Impeller What is a closed impeller? A closed impeller has vanes that are surrounded by a shroud or cover. This improves its efficiency and allows it to pump fluids with suspended solids. Usage of closed Impeller Closed impellers are commonly used in wastewater treatment, paper and pulp, and mining industries. Strength and weakness of closed impeller The strength of a closed impeller is that it is efficient at handling solids. But, a weakness is that it is challenging to clean and maintain.

Semi-Open Impellers:

Semi Open Impeller Definition and uses A semi-open impeller has vanes attached to one side of a central hub with the other side being open. They are suitable for pumping fluids with suspended solids. These are used in chemical, food processing, and mining industries. Differences between open and semi-open impeller Semi-open impellers have higher efficiency than open impellers but are more challenging to manufacture and maintain.

Recessed Impellers:

Definition and uses A recessed impeller has a shroud with a cavity that allows it to handle fluids with high solid content without clogging. They are commonly used in slurry pumping and wastewater treatment. Strength and weakness of closed impeller One strength of recessed impellers is their ability to handle high solid content, but a weakness is their low efficiency.

Vortex Impellers:

Vortex Impeller Definition and uses A vortex impeller has a recessed chamber that creates a vortex, which allows it to handle fluids with high gas content. They are commonly used in the oil and gas industry. Advantages and disadvantages of vortex impellers | strengths and weaknesses They are efficient in pumping liquids with entrained air or gas. One strength of vortex impellers is their ability to handle high gas content, but a weakness is their low efficiency.

When to Choose Which Impeller Type?

Choosing the right impeller type depends on the application and pumped fluid. For instance,

  • Open impellers are suitable for low-viscosity fluids without suspended solids.
  • While closed impellers are suitable for pumping fluids with solids.
  • The choice of impeller type should also consider the desired flow rate, efficiency, maintenance, and cost. 
  • Open impellers are ideal for pumping clean fluids with no solids or particles. In contrast, closed impellers are suitable for pumping fluids with solids, as they prevent clogging.
  • Semi-open impellers are a hybrid of open and closed impellers.
  • Recessed impellers are designed for pumping fluids with high solid content.
  • Vortex impellers, on the other hand, are used for pumping fluids with high gas content.

Impact of Impeller Diameter

Impeller Diameter The diameter of the impeller also affects pump performance.

  • A larger diameter impeller can handle more fluid, resulting in higher flow rates.
  • But it requires more energy to rotate, resulting in higher energy consumption.
  • Conversely, a smaller impeller diameter consumes less energy but handles less fluid, resulting in lower flow rates.

Five Points to Consider When Selecting an Impeller

When selecting an impeller, there are five crucial factors: flow rate, head, specific gravity, viscosity, and solids content. These factors heavily influence the pump’s performance, efficiency, and durability.

1. Flow rate:

The flow rate is the fluid the pump can deliver in a given time, expressed in gallons per minute (GPM). For instance, a pump that delivers 100 GPM is more suitable for high-flow rate applications than one delivers 50 GPM.

2. Head:

Head refers to the maximum height the pump can lift the fluid, expressed in feet or meters. For example, a pump with a head of 50 feet can lift the fluid to a height of 50 feet.

3. Specific gravity:

Specific gravity refers to the ratio of the fluid’s density to the density of water. It determines the fluid’s weight and affects the pump’s efficiency. For instance, a fluid with a specific gravity greater than one is heavier than water and requires more power to pump.

4. Viscosity:

Viscosity refers to the fluid’s resistance to flow, affecting the pump’s efficiency. For instance, a highly viscous fluid requires more power to pump than a low-viscosity fluid.

5. Solids content:

Impeller Solid content The solids content refers to the amount of suspended solids in the pumped fluid. It affects the impeller’s design and performance. For instance, a pump with a closed impeller is suitable.

Which Pump Manufacturer Provides the Best Centrifugal Pumps?

There are a few leading manufacturer and supplier of high-quality centrifugal pumps with excellent impeller sets. Their centrifugal pumps are designed to meet various industrial applications. This includes agriculture to mining. These are built to last, even in harsh environments.  To learn more about their pumps and impeller sets, visit their websites. You can also contact them to find the best pump for your specific needs.

Frequently Asked Questions

What is the function of the impeller?

The main function of an impeller is to transfer energy from the motor. The motor drives the pump to the fluid being pumped. This is achieved by rotating the impeller at high speeds. This creates a centrifugal force that moves the fluid outwards from the center of the impeller and into the pump’s discharge.

What are the three types of impellers?

Axial Impeller flow design Radial Impeller flow design

Impeller flow designs can take on three distinct types: axial, radial, and mixed. Because centrifugal pumps are also classified in this manner, the impeller selection depends upon matching the pump’s flow characteristic to that of the impeller. Read more

What is the advantage of an impeller pump?

One of the main advantages of an impeller pump is its ability to handle fluids with high solids content, such as sewage or slurry. Impeller pumps are also efficient and can handle various flow rates and pressures.

What is the difference between an impeller and a centrifugal pump (impeller vs. centrifugal pump)?

An impeller is a component of a centrifugal pump, which is a type of pump that uses an impeller to transfer energy to a fluid. So, while an impeller is a specific part of a centrifugal pump, the term “centrifugal pump” refers to the entire pump system.

What are the various types of impeller blade designs?

Three different types of impellers are available for most mechanical agitators: flat blade, canted blade, and proprietary. The flat blade impeller moves the fluid radially away from the blades. Read more

Which blades are used in centrifugal pumps?

Generally, centrifugal fans have three types of blades: forward blade, backward blade, and radial blade. Read more

What is the difference between impeller and propeller (impeller vs. propeller)?

An impeller is a type of rotor used in a centrifugal pump, while a propeller is a type of rotor used in a marine propulsion system. Impellers are designed to move fluids, while propellers are designed to move a vehicle through water.

Which blades are the most commonly used blade configuration of a centrifugal pump?

The most commonly used blade configuration for centrifugal pumps is the backward-curved blade. This design is known for its high efficiency and low maintenance requirements.

What is the cost of an impeller?

The cost of an impeller can vary widely depending on factors such as the material it is made from, its size, and its complexity. In general, impellers made from high-quality materials such as stainless steel or titanium will be more expensive than those made from lower-quality materials such as plastic.

Which type of impeller is best?

The best impeller type for a given application will depend on factors such as the fluid type being pumped, and the desired flow rate and pressure. Also, it depends on the specific requirements of the system. Some common types of impellers include closed, semi-open, and open impellers.

What is the principle of pump work?

The principle of pump work is based on the transfer of energy from a motor to a fluid, which is achieved through the use of an impeller. As the impeller rotates, it creates a centrifugal force that moves the fluid from the center of the impeller to the pump’s discharge, thus generating pressure and flow.

What is an impeller also called? (impeller vs agitator) | Difference between impeller and agitator

An impeller is also sometimes called a rotor or an agitator or an impeller wheel.

Which type of impeller is most common?

The most common impeller type is the closed impeller, known for its high efficiency and ability to handle a wide range of fluids and solids. Closed impellers are often used in industrial applications such as wastewater treatment, chemical processing, and mining.


In conclusion, impellers are a crucial component of centrifugal pumps. Understanding their types, functions, and impact on pump performance is essential in choosing the right pump for a specific application. Have a pump project that you want to discuss? Contact us. You can also request a quote or take pump on rentals. Or Simply call our sales expert at 619-558-3250 or email at