How Do Centrifugal Pumps Work?

How Do Centrifugal Pumps Work?

A centrifugal pump operates by converting rotational energy from a motor into energy within a moving liquid. The process works step by step:

1. Suction entry – Liquid enters the pump through the suction eye at the centre of the impeller.
2. Impeller acceleration – The impeller, a rotating component with curved vanes, spins the liquid outward by centrifugal force. (Learn more about impellers in our guide: Pump Impellers – An Overview Of The Different Types)
3. Velocity and pressure conversion – As the liquid moves outward, it gains velocity. The pump casing then converts this velocity into pressure energy, creating a steady and controlled flow.
4. Flow vs. pressure – What the pump truly generates is flow. The pressure observed in the system arises from resistance to that flow—such as friction in pipework, restrictions from valves, or elevation changes. In other words, the system dictates the pressure while the pump provides the flow.
5. Dependence on liquid – For this energy transfer to work, a continuous column of liquid is essential. If air enters the pump, it breaks the hydraulic continuity at the impeller eye, causing the pump to lose its prime and drastically reducing performance. This is why centrifugal pumps must be primed before operation and are unsuitable for pumping gases, unless specifically designed as self-priming or two-phase pumps.

Advantages and Disadvantages of Centrifugal Pumps

Where Are Centrifugal Pumps Commonly Used?

Because of their versatility and efficiency, centrifugal pumps are used in an enormous variety of industries, including:

• Water supply and irrigation – moving clean water in municipal and agricultural systems.
• HVAC systems – circulating hot or chilled water for heating and cooling.
• Wastewater treatment – transporting sewage and industrial effluent.
• Industrial processes – handling chemicals, fuels, and food products.
• Firefighting – providing reliable high-flow water delivery.
• Boiler feed applications – ensuring a steady supply of water at pressure.

Key Components of a Centrifugal Pump

Understanding the main parts of a centrifugal pump is essential for efficient operation and effective troubleshooting. Choosing the right materials also improves performance and extends pump life.

• Impeller – The rotating component that imparts energy to the fluid, creating flow and pressure. Impellers are typically made from stainless steel, bronze, or engineered plastics depending on the fluid type and operating conditions.
• Casing – Encloses the impeller and directs fluid efficiently through the pump. Casings can be volute or diffuser type, and material selection (cast iron, stainless steel, or thermoplastics) depends on chemical compatibility and wear resistance.
• Shaft and Bearings – The shaft transmits power from the motor to the impeller, while bearings support the shaft and reduce friction. Bearing types and lubrication methods vary based on pump size, speed, and load requirements.
• Mechanical Seal or Packing – Prevents leakage between the pump casing and the rotating shaft. Mechanical seals are preferred for high-pressure or hazardous fluids, while packing may still be used for lower-pressure applications.
• Motor Assembly – Powers the pump, typically via an electric motor or diesel engine. Matching motor type and speed to pump design ensures optimal performance and energy efficiency.

Additional Considerations

Selecting the right pump for your application is just the first step—it’s also important to consider what else you’ll need for the job. Below are some items that may be essential, depending on your setup. If you’re unsure about your requirements, our team is always here to help.

Hose – Medium Duty Green Suction

Green suction hose is a medium-duty option for connecting components. More rigid and durable than blue layflat hose, it offers a longer lifespan but is bulkier and harder to store.

Trollies

A trolley is ideal for pumps used across multiple applications, making it easy to move them around your workspace.

Final Thoughts

Centrifugal pumps are the workhorses of fluid handling. By using a simple impeller and casing design, they can deliver high flow rates reliably and cost-effectively. While they do have limitations, such as being unable to handle air and requiring priming, their advantages make them indispensable across industries worldwide.

At TF Pumps, we supply a wide range of centrifugal pumps for different applications. Whether you need a pump for water, chemicals, or industrial processes, our team can help you find the right solution.

Browse our centrifugal pump range here

Additional Reading

Pump Impellers – An Overview Of The Different Types
Understanding Centrifugal Pump Theory