Vertical pumps: what they are and how they differ from horizontal centrifugal pumps

Vertical pumps: what they are and how they differ from horizontal centrifugal pumps

Vertical pumps are frequently adopted in plants where the fluid to be moved is located below the installation point and requires direct management, often within sumps or tanks. In these situations, the pump's configuration influences its installation, startup methods, and ongoing maintenance.

When choosing a solution for fluid transfer, comparison with horizontal centrifugal pumps becomes unavoidable. The two technologies share the centrifugal principle, but they are developed according to different construction logics., in how aspects such as the engine's position, its relationship with the fluid, and how the pump is installed and managed change.

These differences are most evident in sectors where liquids have critical characteristics, such as in the case of corrosive substances, charged liquids, or applications with significant depth. Under these conditions, the choice of configuration must be carefully analyzed and should take into account materials, cycle lengths, and pre-existing characteristics of the plant or territory.

CDR Pompe supports companies in the selection and supply of centrifugal pumps for complex applications, with specific attention to material selection and chemical compatibility. Added to this are technical support and maintenance activities, crucial for ensuring operational continuity and longevity.

What are vertical pumps and how do they work

When talking about vertical pumps, we are referring to a configuration in which the tree is arranged along a vertical axis, with the motor positioned on top and the hydraulic section immersed directly in the fluid.

The transmission of motion in vertical pumps therefore occurs from top to bottom: The motor rotates the shaft, which in turn transfers energy to the submerged impeller. This is precisely where the fluid is accelerated and conveyed, according to the centrifugal principle, along the discharge line. The conversion from mechanical energy to hydraulic energy then takes place within the liquid itself, without a separate intake phase.

This aspect has a direct consequence on the pump's behavior during startup: The impeller's submersion eliminates the need for self-priming., simplifying initial management and reducing some typical critical issues of dry installations of classic horizontal pumps.

The vertical configuration responds to a precise design logic that leads to Separate the engine from the fluid, keeping it in an accessible position, and at the same time to directly intervene on the liquid through an immersed hydraulic part.

Construction features and available configurations

Going into detail, the vertical pumps they do not constitute a single category but include various configurations developed to meet specific needs. The basic structure remains the same, but the way the pump handles total head, flow rate, and fluid characteristics varies.

• Multistage versions, for example, are adopted when it is necessary to increase the pressure through multiple impellers arranged in series along the shaft.
• In applications with high depths, such as wells or basins, recourse is instead made to Vertical turbine pump, designed to work on longer columns and ensure operational continuity.

A central aspect concerns the choice of materials, especially when entering the field of aggressive fluids. Vertical pumps made of polypropylene (PP) or PVDF allow for working in chemically complex environments and ensure, in addition to the pump resistance, also fluid safeguarding, which in this way is protected from contamination or spills (a hazard both to the company’s industrial process and to the environment and the workers who come into contact with it).

This makes it clear the extremely high technological level required for the design of these products, a level that is not limited to the machine's geometry but involves materials, column length, and operating conditions.

Vertical pumps are installed for applications such as:

Generally, vertical pumps find their natural application in all those situations where the fluid is contained below the motor's installation level. Tanks, reservoirs, and wells are the most immediate examples, but their use extends to various industrial fields.

• In the chemical sector, for example, are used to move corrosive liquids or solutions with variable characteristics, keeping the more delicate part of the pump away from direct contact with the fluid.
• In wastewater treatment, on the other hand, allow for the management of liquids loaded with particles or residues, operating directly inside the tanks.

The ability to work submerged makes these pumps suitable for significant depths as well., where other configurations would encounter greater difficulties. At the same time, Vertical development allows for a smaller footprint., making it easy to integrate into existing systems or in limited spaces.

In many applications, therefore, The choice of vertical pumps arises from the need to adapt to the plant's structure, more than from a preference tied solely to technology.

Operational advantages of vertical pumps

Vertical pumps are chosen when fluid management requires direct interaction with the liquid and a configuration capable of adapting to installations in deep or confined spaces. The advantages derived from their installation therefore stem precisely from their particular construction characteristics:

• Absence of self-priming
  The impeller immersed in the fluid allows the pump to operate without the need for pre-filling. This reduces start-up risks and simplifies initial management, especially when dealing with difficult liquids.
• Separate motor from fluid
  The motor is installed above the tank and does not come into direct contact with the liquid. This configuration limits exposure to corrosive substances and facilitates routine inspection and maintenance operations.
• Reduced footprint
  Vertical development allows for less floor space to be occupied, a useful characteristic in compact or already structured systems where available area is limited.
• Absence or reduction of the suction line
  The pump works directly within the liquid, avoiding pressure losses typical of suction lines and improving flow continuity.
• Adaptability to high depths
  Thanks to their column structure, vertical pumps can operate even with deep water levels, maintaining consistent performance.
• Reduced risk of dry running
  The impeller's position reduces the likelihood of the pump running dry, a condition that can cause significant damage in traditional configurations.

What are horizontal centrifugal pumps and how do they work

To better understand the differences, let's now look at how horizontal centrifugal pumps are developed. In this case, the shaft is arranged on a horizontal plane and directly connects the engine to the pump casing, both installed on a base.

This configuration leads to a linear arrangement of components, which are easily accessible: the fluid is thus drawn through a dedicated line and subsequently set in motion by the impeller, following the same centrifugal principle as seen for vertical pumps.

Unlike submersion installations, here the pump operates in a dry environment, And this requires more careful management of the suction phase, which must be designed to avoid serious problems and failures such as cavitation or dry running.

The popularity of this type of pump, which features prominently in the CDR Pompe catalog, is also due to its versatility: Horizontal pumps can be easily integrated into many existing system configurations without the need for major interventions, thus maintaining a simple structure to manage.

Applications of horizontal pumps

Horizontal centrifugal pumps are used in a wide range of applications precisely because of their ability to adapt to different contexts. They are present, for example, in water treatment plants, in industrial production lines, and in fluid transfer systems between different points in the plant.

When the liquid is at an accessible level and there is no need to operate at depth, this configuration allows for the construction of neat and easily inspectable systems. Mounting on a base also simplifies integration with other components, such as valves, piping, and control systems.

In the chemical and pharmaceutical sectors, Horizontal pumps are therefore often used for transferring fluids along process lines, where continuity and precision in flow management are required.

Their diffusion, therefore, is linked to the possibility of incorporating them into consolidated plant designs, without particular constraints related to depth or fluid position.

Maintenance and Management: Operational Differences

When it comes to management over time, the differences between vertical pumps and horizontal pumps become more apparent. In the case of vertical pumps, the motor remains easily accessible, but the hydraulic part, being submerged, requires more structured operations to be reached.

Intervening on the impeller or internal components means, in most cases, removing the pump from the tank or vessel, with intervention times and methods that must be considered from the design phase.

Horizontal pumps follow a different logic, in which all components are installed on a single plane and can be accessed without complex preliminary operations. This allows for faster interventions and reduced plant downtime.

The choice between the two configurations, therefore, not only concerns the initial installation but also how the pump will be managed throughout its lifecycle.

Differences between vertical and horizontal pumps

The comparison between vertical pumps and horizontal centrifugal pumps requires observing how each solution integrates into the system and handles the fluid. The differences concern not only the arrangement of components but also installation, operation, and maintenance.

• Structure and orientation
  Vertical pumps have a vertically oriented shaft, with the impeller submerged in the fluid and the motor positioned at the top. Horizontal pumps, on the other hand, have all components arranged on a horizontal plane, with the engine and pump casing mounted on a base.
• Installation Modes
  Vertical pumps are inserted directly into sumps or tanks, operating in contact with the liquid. Horizontal pumps, on the other hand, require a stable base and a suction line designed to convey the fluid to the impeller.
• Management of’startup
  In vertical pumps, the presence of fluid around the impeller eliminates the need for self-priming. Horizontal pumps, on the other hand, must be handled carefully during startup to avoid problems related to the presence of air.
• Typical applications
  Vertical pumps are used for liquids at depth, aggressive fluids, or situations requiring submersion. Horizontal pumps are common in transfer and distribution systems along process lines.
• Maintenance
  Vertical pumps require extraction from the tank to service the hydraulic section, while horizontal pumps allow direct access to all components, reducing service time.

How to choose between vertical and horizontal pumps

The first element to consider is the position of the liquid: When located inside tanks or at significant depths, vertical pumps allow for direct withdrawal, avoiding complex suction systems.

The available space also affects the choice: Vertical pumps are developed in height and require less ground surface, while horizontal pumps need a base and a more extensive layout.

A further factor concerns, as we have seen, maintenance: If the system requires frequent interventions and immediate access to components, the horizontal configuration facilitates operations. Conversely, if the goal is to limit contact between the motor and the fluid and to work submerged, vertical pumps are more suitable.

Finally, the sizing must take into account flow rate, total head, and operating conditions. An accurate assessment of these parameters allows for the identification of the most consistent solution, avoiding critical issues during operation and ensuring continuity over time.

Guide to choosing vertical or horizontal pumps with CDR

Vertical pumps and horizontal centrifugal pumps represent two established configurations developed to meet different fluid management needs. Their effectiveness depends on the ability to fit them into the correct context, taking into account the structure of the system and the characteristics of the fluid.

The differences that emerged concernavailable to the components, installation methods, usage areas, and maintenance management. Elements that, read together, allow for a more informed choice.

With over half a century of experience in the management and handling of aggressive, corrosive, and hazardous fluids, CDR Pompe is able to guide its customers toward the best possible configuration. In addition, our company offers a’dedicated support not only for sale, but also for installation, commissioning, spare parts, and regular maintenance of the product, including through a network of partners and distributors located throughout Europe and beyond.

Contact our center for a dedicated consultation and to get much more information on our catalog of pumps and all our services for the chemical and pharmaceutical industry.

Frequently Asked Questions

What is a vertical pump and how does it work compared to a horizontal centrifugal pump?

A vertical pump has the shaft on a vertical axis, the motor at the top and the hydraulic section immersed in the fluid. The motor rotates the shaft, which transmits energy to the impeller immersed part according to the centrifugal principle. In the horizontal pump, the shaft, the motor and the pump pump casing are on a base and the liquid comes from a dedicated suction line.

Do vertical pumps need priming?

No, vertical pumps do not require priming, because the pump impeller is already immersed in the fluid and can start up without a preliminary fill. This simplifies start-up and reduces the risk of dry running. Horizontal pumps, which operate dry, require careful start-up management to avoid air, cavitation and failure.

What is the difference between multistage vertical pumps and vertical turbine pumps?

Multistage vertical pumps use multiple rotating elements in series along the shaft to increase pressure; therefore, they are suitable for high-pressure applications total head. Vertical turbine pumps are designed for long columns and high depths, such as wells and reservoirs. The choice depends on the total head requirement, the fluid depth, and operating conditions.

Do vertical pumps require less maintenance than horizontal pumps?

Not necessarily: change the type of intervention, not the frequency. In vertical pumps the motor is accessible and away from the corrosive liquid, but to intervene on it usually impeller requires removing the pump from the tank or reservoir. In horizontal pumps all components are directly accessible, with faster interventions and shorter downtime for the system.

What are the limitations of vertical pumps and when is it advisable to choose a horizontal pump?

The limitations of vertical pumps are the longer time required to access the hydraulic part, which requires extraction from the tank, and the height of the structure, which must be compatible with the space. A high shaft length can also create mechanical stresses. If frequent interventions and immediate access to the components are required, a horizontal pump is advisable.

Is it possible to replace a horizontal pump with a vertical pump in an existing system?

Replacement is not always immediate, because the two configurations require different installation conditions. A vertical pump requires a basin or tank to be immersed in, while a horizontal one works on a base with an intake line. Before replacing it, the configuration of the system, the fluid’s position, and the required performance must be evaluated.