Multistage Pumps: Go-To Guide for Types, Applications, and Working Principles

The multistage pump is the most advanced and efficient device for delivering water to its required destination across various domestic and industrial sectors. 

The main distinguishing feature of this unit’s operating system is using multiple impellers to generate high water pressure, ensuring performance and efficiency. These devices take water to great heights or pump it from considerable depths to provide water supply, heating, air conditioning, firefighting, and more. 

Thanks to the high functionality, reliability, and ease of operation, multistage compressors are widely used in both industrial applications and everyday domestic settings. 

What is a multistage pump? Let’s explore its types, applications, and working principles.

How Does a Multistage Pump Work?

Multistage water movers are in demand for households, agriculture, and industry. They underpin irrigation systems, ensure water supply, facilitate the pumping of liquids to various buildings and facilities, and support heating systems. 

Unlike the centrifugal pump, the main principle of the multistage pump working process is the increasing fluid pressure at each stage due to several impellers. The system operates based on fluid mechanics, converting the kinetic energy of rotating impellers into high liquid pressure and ensuring effective delivery over significant distances.

Key Components of a Multistage Pump

The primary components of high-pressure pumps with a multistage system are the casing, impellers, shaft, bearings, and seals. Each element serves its specific function, ensuring a seamless and efficient operational process.

• The casing is a key protective part that ensures the system’s seal integrity. A well-designed casing also helps minimise energy losses and enhances overall efficiency.
• Impellers and stages are the primary driving force of the mechanism. They convert mechanical energy into kinetic energy, generate the required pressure, and accelerate the fluid flow. They are installed in sequence to gradually increase pressure at each stage.
• The shaft transfers mechanical energy and maintains the rotation of the impellers with high precision and speed, ensuring smooth fluid movement through the pump. The shaft must be robust enough to withstand the forces generated during the rotation of the impellers.
• Bearings ensure the slick rotation of the shaft and reduce friction between moving parts. They also play a crucial role in maintaining the stability of the shaft, preventing vibrations, and guaranteeing the unit operates reliably even under heavy loads.
• High-quality seals prevent fluid leakage from the unit and protect the internal components from contamination or air ingress. They provide a seal between the rotating and stationary parts of the equipment and are essential for maintaining the required pressure within the system.

The Multistage Pump Process

Multistage systems create high water pressure and maintain a stable flow by increasing the pressure level at each stage. This process makes these machines ideal for water supply systems, industrial equipment, and heating and cooling systems that need significant pressure to transport liquids effectively. 

Below is a step-by-step explanation of how water moves through each stage of a multistage pump:

• Step 1. Water enters the unit through the inlet port. At this point, it remains at atmospheric pressure or a slightly low initial pressure, ready for the next stage.
• Step 2. The first stage starts as the shaft turns, with the first impeller producing centrifugal force. This action speeds up the water, transforming mechanical energy into kinetic energy. When the water leaves this zone, its pressure rises.
• Step 3. Water moves to the second stage through the suction-discharge channel. Guide vanes ensure smooth water flow, reducing energy loss.
• Step 4. In the second and the next stages, the impeller acts on the water again. At this point, the pressure increases further due to additional acceleration and the creation of higher authority. Each subsequent stage continues this process, gradually increasing the overall water pressure until it reaches the required level for a specific application. The number of stages depends on the necessary head and the system features where the pump operates.
• Step 5. Once the water passes through all the stages, it flows out of the machine via the discharge valve under high pressure. You get efficient water delivery over long distances or seamless integration into high-pressure systems.

Types of Multistage Pumps

Good to know: many multistage pumps feature adjustment and control systems that maintain a steady flow and reliable water pressure. These systems often include pressure regulators, sensors, and automated controls that fine-tune device performance in response to system changes.

A detailed comparison of single-stage vs. multistage pumps highlights the significant advantages of the latter. 

Unlike basic models, they are classified by the design and configuration of their primary components, which directly influence their performance and suitability for various applications of multistage machines. Choosing the type of device depends on operating conditions, the required pressure, installation specifics, and the pump head coefficient.

Horizontal Multistage Pumps

Horizontal multistage suction devices are powerful equipment designed to generate high pressure and ensure a stable water flow. Their design includes several distinctive features, making them indispensable for complex tasks and specific conditions. 

The main advantage is their ability to deliver water over long distances under high pressure efficiently. Designed for durability, horizontal multistage pumps handle heavy workloads and require minimal maintenance, which makes them especially valuable for large-scale industrial operations. 

The construction includes a broad support base, providing excellent resistance to vibrations and heavy loads. These water pressure systems deliver consistent performance in systems that demand stability and extended processes without requiring exact alignment or risking imbalance. All key pump components, including impellers, the shaft, and bearings, are easily accessible for maintenance without needing to dismantle the entire unit.

The horizontal design is ideal for:

1. Facilities: when ample space is available, horizontal pumps offer easier maintenance.
2. Stability: they are less prone to vibrations, making them suitable for long-term operation.
3. High water volumes: these pumps are optimal for systems with huge flow rates and heavy workloads.

Horizontal multistage machines supply liquid to high-pressure boilers in thermal power plants to operate steam generators. Their design ensures reliable handling of large volumes of water over long distances, delivering durability and requiring minimal maintenance costs.

Vertical Multistage Pumps

Vertical pumps are an optimal choice for applications that demand compactness and flexibility. Their design is practical, with impellers arranged along a vertical shaft to minimise space requirements. This solution is ideal for compact spaces, such as pump stations in the basements of high-rise buildings or sites with limited floor area. 

Vertical models are adaptable and effectively handle fluctuating water levels, making them perfect for use in wells and large tanks. The key components of items are positioned above the liquid or floor level. To select the right vertical item, you need to determine the required flow rate and head height. Additionally, it is essential to identify the type and density of the liquid. Understanding these factors ensures the pump will meet the specific needs of your application.

A vertical design pump is best suited for:

1. Limited space: when only a small area is available, vertical pumps minimise the required footprint.
2. Low water levels: ideal for handling deep tanks and wells, ensuring efficient operation;
3. Flood protection: pump components are positioned above floor level, reducing the risk of damage during flooding;
4. Specialised applications: perfect for high-rise buildings, cooling systems, and commercial and industrial sites where compactness and high performance are critical.

Tailored for urban environments, multistage vertical pumps operate in water supply systems for high-rise buildings, including residential complexes, hotels, and office towers. They deliver consistent water pressure to upper floors, even during peak demand. The compact design allows these vacuum systems to be installed in the confined spaces of utility rooms, ensuring efficient use of available area.

Final Thoughts on Multistage Pumps

Multi-stage pumps are essential across various industries that require precise high-pressure control and reliable fluid movement. Their design, featuring multiple impellers arranged sequentially on a single shaft, ensures a steady pressure increase and delivers exceptional performance. This versatility makes them widely used in applications ranging from supplying water to high-rise buildings to maintaining stable pressure in power station boilers. Horizontal models offer enhanced stability and easier maintenance, while vertical designs excel in environments where space is limited.

Always prioritise regular maintenance to ensure pump efficiency and uninterrupted operation. Check the condition of bearings, seals, and impellers frequently. Address wear and tear promptly, and monitor the quality of the fluid. Taking a comprehensive approach to maintenance ensures equipment delivers high performance and operates reliably, even in the most critical projects.

You can also explore our recommendations on why investing in grey water pumps is a smart choice today, along with detailed insights into their classifications and applications.