Centrifugal Pumps: How They Work and What They Involve

Many industrial and municipal applications use centrifugal pumps in their production processes. Petrochemical manufacturing, pharmaceutics, food and beverage production, water and wastewater industries all use centrifugal pumps to optimize their processes. Understanding how centrifugal pumps work is critical to choosing the right configuration for any given industrial setup.  

About Industrial Centrifugal Pumps

Centrifugal pumps are pressure-producing mechanical devices that transfer kinetic energy generated from centrifugal force to hydrodynamic energy resulting in the flow of all kinds of fluids that are required for industrial and municipal processes.

How Do Centrifugal Pumps Work?

Centrifugal pumps operate on the principles of rotational energy transmission. Fluid supplied through a nozzle is directed at an impeller within the pumping system generating rotational energy. Part of the kinetic energy generated from the whirling of the impeller blades is transmitted to fluid. The energized fluid then enters a volute casing or diffuser and decelerates while increasing the pressure.  

Types of Centrifugal Pump Systems

Centrifugal pumps come in varied configurations which are suited for different industrial applications. The most popular variants are listed below.

• Axial and mixed flow vertical and horizontal centrifugal pumps
• Radial flow vertical and horizontal centrifugal pumps
• Electric, engine and hydraulically driven centrifugal pumps
• Single and multistage centrifugal pumps
• Vertical turbine and vertical sump centrifugal pumps
• Submersible centrifugal pumps

ANSI vs. API Pumps: What Do They Mean?

The centrifugal pumps used for most mechanical pumping systems across the USA are manufactured to meet certain engineering standards. The two most popular standards are written by the American National Standards Institute (ANSI) and American Petroleum Institute (API).

ANSI pumps are generally high-quality single stage centrifugal pumps built for low maintenance and high efficiency with standardized footprints and internal specifications and were originally designed for use in the chemical process industry, but now are also being specified for use in most other industrial markets. API pumps are single and multistage centrifugal pumps manufactured to meet strict specifications and are primarily required for high pressure and high temperature applications within the oil and gas industry.  Both ANSI and API pumps are radial centrifugal pumps and are available in many sizes, metallurgies and configurations.

Key Application of Centrifugal Pumps

Some key industrial applications that benefit from the use of centrifugal pumps are outlined below:

• Commercial food processing
• Alcoholic beverage manufacturing
• Chemical product synthesis
• Oil and gas recovery
• Residential waterworks
• Fire protection systems
• Sewage/slurry disposal systems

Centrifugal Pump Parts

A standard centrifugal pump requires the following components to function properly:

• An impeller
• Diffuser or volute casing
• Shaft and shaft sleeves
• Bearings
• Mechanical seals, Packing and Casing Cover

Impeller

The impeller is connected to the shaft and it rotates at the same speed as the shaft, which is powered by some sort of power device like a motor, engine or hydraulic unit. As fluid enters the eye of the impeller it is directed into and then through the vanes of the impeller where it picks up velocity and kinetic energy.  By the time the fluid leaves the vanes and enters into the casing the velocity of the fluid equals the rotational speed of the impeller. 

Diffuser/Volute Casing

Diffusers and volutes are two variants of centrifugal pump casings responsible for containing the fluids and is where the fluid pressure is generated.  The translational kinetic velocity energy in the fluid is slowed down on entry into either a volute or a diffuser, an action that converts fluid velocity into fluid pressure.

Shaft and Shaft Sleeves

The shaft is the central unit in a centrifugal pump’s rotor system. It bears the impellers, mechanical seal and the bearings of the pump. The shaft acts as a rigid framework from which pump operations can be conducted

Bearings

Bearings installed on the shaft within the centrifugal pump’s bearing housing act to support the shaft and other rotary elements with the stationary pump components. Bearings absorb the radial and axial forces that are caused during pump operations and help keep the pump shaft aligned which is needed for the pump to operate at peak efficiency and reliability.  There are different types of bearings that are used in centrifugal pumps based on the operating conditions of the pump.

Examples include:

• Anti-friction bearings
• Pivoted-shoe thrust bearings
• Sleeve bearings

Mechanical Seals

The mechanical seal or packings are crucial pump components designed to keep the liquid being contained inside the casing from leaking out along the rotating shaft.  The mechanical seal or packing are housed within the casing cover that forms the back of the casing. Various types of sealing arrangements can be used depending on process variables. Crucial criteria to consider before selecting a mechanical seal or packing include:

• The nature of process fluid to be pumped
• The pump’s operational temperature and pressure

Centrifugal Pump Diagram

The diagram above shows the essential components of any standard centrifugal pump system.

Additional Centrifugal Pump Resources

The entire knowledge base on the various components, variants, and uses of centrifugal pumps cannot be exhausted in a single article. For individuals and organizations looking to gain more information on this critical industrial equipment, a few additional resources are outlined below:

• Different Types of Centrifugal Pumps and Their Applications
• How to Read a Pump Curve for Centrifugal Pumps
• Centrifugal Pump Maintenance Procedures for Industrial Pumps

The DXP articles listed above provide additional insight into the operation of industrial centrifugal pump systems.

Partnering with a Centrifugal Pump Supplier

While choosing the right centrifugal pump type is critical to the success of any associated industrial processes, selecting a process pump supplier that understands your unique application is equally important.

At DXP, we offer the best centrifugal pump solutions to partners across diverse industrial endeavors.

To learn more about how DXP can optimize your pumping process, please contact us today!