What Are Multistage Pumps?
Centrifugal pumps are the most widely available and widely used pump type on the market due to their relative simplicity of design. Centrifugal pumps are classified into two types based on the number of impellers: single-stage and multistage.
A single impeller is used in single-stage pumps. As a result, the discharge pressure is proportional to the impeller size. As a result, these pumps are a better fit for higher flow, lower pressure installations.
Multistage pumps have a flexible range of flow and head and a relatively higher degree of energy efficiency, making them an excellent choice for many applications. In addition, a multistage pump circulates fluid through two or more impellers connected in series. As a result, such a pump will have multiple liquid chambers or stages linked in series. Each stage comprises an impeller, a diffuser, and return guide vanes, all housed within the same stage casing.
These impellers are connected in series and rotate on a single shaft powered by an external source, usually a motor. The design of multistage pumps allows fluid to flow only linearly through the chambers.
After priming the pump, the fluid enters the first chamber through the pump inlet at suction line pressure. The fluid then flows sequentially from left to right through various impellers, or vice versa, depending on the design of the pump. Finally, the fluid exits at high pressure. Each impeller feeds into the next, and the pressure increases with each stage.
The higher the final discharge pressure, the more stages or impellers there are in a pump. While the fluid pressure increases with each stage, the flow range remains constant for any given RPM.
Multistage pump types
There are many different types of multistage pumps, as listed below, but the most common ones are vertical and horizontal pumps.
• Horizontal multistage centrifugal pump (above ground)
• Horizontal split case pumps
• Sanitary multistage pumps
• Side channel pumps
• Submersible/sump pumps
• Vertical multistage centrifugal pump (above ground)
• Vertical turbine pumps
Because multistage centrifugal pumps have multiple impellers, they can increase water pressure in series from one stage to the next, delivering higher pressures than a similarly sized single-impeller pump. In addition, because the head per stage is lower, smaller impellers with tight tolerances can be used, reducing leakage loss.
In addition, multistage pumps help to save space on the floor. Because of the smaller impeller diameters and tighter clearances, these pumps require less motor horsepower, resulting in increased performance and efficiency. In addition, adding stages reduces noise levels for pumps with the same discharge pressure output compared to a single-stage pump.
Disadvantages of multistage pumps
Multistage pumps have a more complex design and a greater number of moving components than single-stage pumps. As a result, the repair and maintenance of these pumps are relatively expensive and necessitate a higher level of technical expertise.
Furthermore, tighter tolerances prohibit the presence of solids in the fluid flow, which is why multistage pumps are commonly used to transport water or other low-viscosity fluids.
In addition, because such pumps have multiple stages, the pump rotor is more sensitive to external or natural vibrations.
A multistage pump has applications in a wide range of industry verticals that require the movement of fluids. For example, high-rise buildings require higher pressure to deliver water to their overhead tanks. For such applications, multistage pumps are commonly used. They are also frequently used to increase the pressure in the water system or circulate water continuously.
Other important multistage pump applications include:
• Boiler feeder pumps in power plants
• Fuel delivery
• Oil and gas production
• Pressurising water for firefighting
• Pressurising water to create snow for sports and resorts
• Reverse osmosis
If you need help deciding on a multistage pump for your fluid transportation needs, contact our experienced engineers to assist you. Ernest Electro Engineering is a leader in the local pump industry and has a great selection of multistage pumps. If you want to learn more about the pump industry and our other offers and solutions, please continue browsing our website for details.