Types of Centrifugal Pumps: A Complete Classification Guide

Table of Contents

1. How Centrifugal Pumps Are Classified
2. Types by Flow Direction
3. Types by Number of Stages
4. Types by Pump Orientation
5. Types by Impeller Design
6. Types by Suction Design
7. Types by Application and Construction
8. Key Parts of a Centrifugal Pump
9. How to Choose the Right Type
10. Sintech’s Centrifugal Pump Range
11. Conclusion
12. FAQs

Centrifugal pumps are grouped into six main categories: flow direction, number of stages, orientation, impeller design, suction arrangement, and application or construction. Each category answers a different design question, such as how the liquid moves through the casing, how much pressure the job needs, or how the pump mounts on the foundation. This guide walks through all six classifications, with the specific pump models Sintech builds for each one.

Ask five engineers to name “types of centrifugal pumps” and you’ll get five different answers. One will talk about horizontal and vertical. Another will talk about single-stage and multistage. A third will start with an impeller shape. None of them are wrong. Centrifugal pumps don’t fall into one classification system, they fall into several, layered on top of each other, and a single pump usually belongs to four or five categories at once.

That layering is exactly what trips up a lot of pump selection. An engineer at Sintech Pumps, headquartered in Ghaziabad, Uttar Pradesh, gets asked almost weekly to explain why a “horizontal centrifugal pump” and a “single-stage centrifugal pump” aren’t competing options, they’re often the same physical pump described two different ways. This guide untangles the classification systems behind the various types of centrifugal pumps and shows where Sintech’s own product range fits into each one.

Before comparing pump types, it helps to know the six lenses engineers use to describe them. A single pump can be classified by:

Flow direction, meaning whether the liquid exits the impeller radially, axially, or at an angle between the two.

Number of stages, meaning how many impellers work in series inside one casing.

Orientation, meaning whether the shaft is mounted horizontally or vertically.

Impeller design, meaning whether the impeller vanes are open, semi-open, or fully enclosed.

Suction design, meaning whether liquid enters from one side of the impeller or both.

Application and construction, meaning the physical build chosen for a specific job, such as split casing, self-priming, or submersible.

A single Sintech pump model can sit in five of these six buckets simultaneously. A CPS end-suction pump, for instance, is a radial-flow, single-stage, horizontal, closed-impeller, single-suction machine. Once that layering makes sense, pump selection stops feeling like guesswork.

Flow direction describes the path the liquid takes as it leaves the impeller, and it’s the classification that determines head and flow characteristics more than any other.

1. Radial Flow Pumps

In a radial flow pump, liquid enters along the shaft and exits at a right angle to it, pushed outward by centrifugal force generated inside the impeller. This is the working principle behind most process and utility pumps, including Sintech’s CPS centrifugal pump range built to ISO 2858 and ISO 5199. Radial flow suits applications needing moderate flow at higher head, from boiler feed circuits to general plant water transfer.

2. Axial Flow Pumps

An axial flow pump moves liquid parallel to the shaft, more like a ship’s propeller than a conventional impeller. There’s very little pressure rise per stage, but the flow volume is high. Sintech’s SAF and SVAF axial flow pumps are built for exactly this profile: large-volume, low-head jobs such as flood control, drainage, and cooling water circulation where moving a lot of water quickly matters more than building pressure.

3. Mixed Flow Pumps

Mixed flow pumps sit between the two, discharging liquid at an angle that combines radial and axial movement. They deliver a useful middle ground of moderate head at high flow. Sintech’s SMF (horizontal mixed flow) and SVMF (vertical mixed flow) pumps handle large-volume liquids, whether clean or contaminated, in applications like effluent transfer and large-diameter irrigation mains.

This classification counts how many impellers sit in series inside one pump casing, and it directly determines how much head the pump can generate.

1. Single-Stage Centrifugal Pumps

A single-stage pump has one impeller doing all the work. It’s the simplest, most serviceable configuration and covers the majority of general industrial duties: cooling water, process transfer, and effluent handling where head requirements stay under roughly 100 metres.

2. Multistage Centrifugal Pumps

A multistage centrifugal pump stacks two or more impellers in series, with liquid discharged from the first impeller feeding directly into the suction of the second. Each stage adds head, so a five-stage pump can reach roughly five times the pressure of one stage running at the same speed. Sintech’s multistage high-pressure pump range is built for boiler feed water, high-pressure process lines, and reverse osmosis feed duty, where a single impeller simply can’t build enough head on its own. A 550 MW thermal power plant boiler feed line, for example, routinely needs total dynamic head (TDH) in the 1,500-2,000 metre range, a job that belongs to a multistage machine, not a single-stage one, no matter how large the impeller.

Orientation refers to how the shaft is mounted, and it’s usually decided by available floor space, suction conditions, and flood risk rather than hydraulic performance alone.

1. Horizontal Centrifugal Pumps

A horizontal centrifugal pump mounts with the shaft parallel to the ground. This is the default choice for most plant installations because it’s easier to align, easier to service (the whole rotating assembly can be pulled without disturbing the piping), and generally costs less to install. Sintech’s CPS, SCS, and STF ranges are all available in horizontal configuration.

2. Vertical Centrifugal Pumps

A vertical centrifugal pump mounts with the shaft perpendicular to the ground, often with the impeller submerged in a sump or well below the motor. This orientation saves floor space and, in the case of Sintech’s SVT vertical turbine pumps, allows the pump to draw water from depths of over 300 metres, which is why they’re the standard choice for deep tube well irrigation and canal-based water supply schemes across the UP sugar belt and similar agricultural regions. Sintech’s vertical sump pumps (STFV/CPSV) follow the same logic for process sump drainage, where the pump needs to sit directly in the pit rather than pull suction from a remote tank.

Impeller design determines how well a pump tolerates solids, air, and abrasive particles in the liquid.

1. Open Impeller

An open impeller has vanes attached only to a central hub, with no shrouding on either side. It handles liquids with suspended solids reasonably well and is easier to clean, but it runs at slightly lower efficiency because of internal recirculation losses.

2. Semi-Open Impeller

A semi-open impeller adds a shroud on one side of the vanes, improving efficiency over an open design while still tolerating some solids content. This is a common middle-ground choice for process liquids that aren’t perfectly clean but also aren’t heavily loaded with abrasives.

3. Closed Impeller

A closed impeller has shrouds on both sides of the vanes, sealing the flow path completely. It delivers the highest hydraulic efficiency of the three but needs cleaner liquid to avoid clogging. Most of Sintech’s standard CPS process pumps ship with closed impellers for exactly this reason.

For genuinely difficult liquids, sugar mill juice with pulp and fibre, wastewater sludge, or abrasive slurry, none of the three standard impeller types is ideal. That’s the gap Sintech’s torque flow pump (STF) fills, using a recessed impeller set back from the casing so the liquid itself does most of the pumping work, with almost nothing in the flow path to clog.

Suction design describes how many sides of the impeller receive incoming liquid, and it matters most when flow requirements get large.

1. Single-Suction (End-Suction) Pumps

In a single-suction pump, liquid enters from one side of the impeller only. This is the standard arrangement for most centrifugal pumps below roughly 500 cubic metres per hour and is the configuration used across Sintech’s CPS end-suction range.

2. Double-Suction (Split-Case) Pumps

A double-suction pump splits the incoming flow so liquid enters both sides of the impeller simultaneously. This balances axial thrust on the shaft, extends bearing life, and roughly doubles the flow capacity for a given impeller diameter compared to single-suction. Sintech’s SCS split casing double suction pumps are built for exactly this high-flow, low-maintenance duty, common in power plant cooling water and large water treatment intakes.

Beyond hydraulic classification, pumps are often described by their physical build for a specific job.

End-suction pumps cover general-purpose transfer duty and are the most common construction in industrial plants.

Split-case pumps, as covered above, handle high-flow water transfer with easier maintenance access since the top casing lifts off without disturbing the piping.

Self-priming pumps can evacuate air from the suction line on startup, useful where the pump sits above the liquid level and can’t rely on flooded suction.

Submersible centrifugal pumps operate fully submerged in the liquid, common in sump drainage and dewatering.

Inline pumps mount directly in the pipeline without a separate baseplate, saving space in tight process areas.

Process pumps built to API 610 serve petroleum and heavy chemical duty with stricter sealing and materials requirements than standard ISO 2858 pumps; Sintech’s chemical-duty CPS variants are built to ISO 5199, the equivalent European standard for this category.

Every classification above still comes back to the same basic components. The impeller converts rotational energy from the motor into velocity in the liquid. The casing (or volute) converts that velocity into pressure as the liquid slows down on its way to the discharge nozzle. The shaft transmits torque from the motor to the impeller and is supported by bearings on either end. The seal, either a mechanical seal or gland packing, prevents liquid from leaking out along the shaft. Get any one of these wrong for the application and the classification choice above it stops mattering. A closed impeller on a clean water duty is pointless if the mechanical seal isn’t rated for the process temperature.

Working through the classifications above, the actual selection comes down to five inputs.

Flow rate: how many cubic metres per hour the process needs, which narrows the choice between single-suction and double-suction, or standard and axial flow.

Head requirement: how much pressure the liquid needs at discharge, which decides single-stage versus multistage.

Fluid character: whether the liquid is clean, viscous, or carries solids, which decides impeller type and whether a standard CPS pump or a torque flow STF pump is the right call.

Material of construction: cast iron for clean water duty, stainless steel or duplex alloys for corrosive or chemical process liquids.

Installation environment: available floor space, flood risk, and suction conditions, which decide horizontal versus vertical orientation.

A sugar mill in the Muzaffarnagar-Saharanpur belt evaluating juice extraction pumps, for example, will rule out a standard closed-impeller CPS pump almost immediately once fibre content enters the picture, and land on either an open-impeller variant or a dynamic sealing pump instead.

Sintech Pumps has been building centrifugal pumps to ISO 2858, ISO 5199, and DIN 24255 since 1986, with ISO 9001-certified manufacturing out of Ghaziabad. The centrifugal pump (CPS) range covers general process and chemical duty, the split casing double suction (SCS) range handles high-flow water transfer, and the torque flow pump (STF) line takes over where solids or fibre rule out a conventional impeller. For deep well and canal-fed irrigation duty, the vertical turbine pump (SVT) range is engineered for depths beyond 300 metres. None of these are drop-in replacements for each other; matching the right one to a process condition is the whole point of the classification system above.

Classifying centrifugal pumps by a single label rarely tells the full story. A real specification stacks four or five of the six systems above- flow direction, stage count, orientation, impeller type, and suction design- until only one type of pump actually fits the job. If you’re specifying pumps for a new line or replacing one that’s underperforming, Sintech’s application engineering team can review your flow, head, and fluid data and confirm which configuration actually fits, rather than which one happens to be in stock. Reach out at info@sintechpumps.com or call +91 120 4176000.

What are the main types of centrifugal pumps? 

Centrifugal pumps are classified by flow direction (radial, axial, mixed), number of stages (single-stage, multistage), orientation (horizontal, vertical), impeller design (open, semi-open, closed), suction design (single-suction, double-suction), and construction (end-suction, split-case, self-priming, submersible, inline).

What is the difference between single-stage and multistage centrifugal pumps? 

A single-stage pump uses one impeller and suits head requirements under roughly 100 metres. A multistage pump stacks impellers in series, with each stage adding head, making it the right choice for boiler feed water and high-pressure process lines.

Which type of centrifugal pump is used for high pressure? 

Multistage centrifugal pumps are used for high-pressure duty because each additional impeller stage adds head, allowing the pump to reach pressures a single-stage machine can’t achieve at the same speed.

Horizontal vs vertical centrifugal pump, which is better? 

Neither is universally better. Horizontal pumps are easier to align and service and suit most plant floor installations. Vertical pumps save floor space and, in models like Sintech’s SVT, can draw water from depths beyond 300 metres, making them the standard for deep well and sump applications.

What is a double-suction centrifugal pump used for? 

A double-suction (split-case) pump is used where high flow rates and balanced shaft thrust matter, such as power plant cooling water systems and large water treatment plant intakes.

Why does impeller type matter in centrifugal pump selection? 

Impeller type determines how well a pump handles solids and abrasive particles. Open and semi-open impellers tolerate some solids content, while closed impellers deliver higher efficiency but need cleaner liquid to avoid clogging.

Can a centrifugal pump handle liquids with solids or fibre? 

A standard closed-impeller centrifugal pump struggles with solids-laden or fibrous liquids. Torque flow pumps, which use a recessed impeller set back from the flow path, are built specifically for this duty and are common in sugar mill juice lines and wastewater plants.

What standards govern centrifugal pump manufacturing in India? 

Indian and international centrifugal pump manufacturing commonly references ISO 2858 and DIN 24255 for standard process pumps, ISO 5199 for chemical duty, and IS 9137 for acceptance testing at the manufacturer’s works.

How deep can a vertical turbine pump draw water from? 

Sintech’s vertical turbine pumps (SVT) can operate at depths of up to 300 metres, making them suitable for deep tube well irrigation and canal-based water supply schemes.

Do all centrifugal pumps use the same impeller? 

No. Impeller choice depends on the liquid being handled. Clean water applications typically use closed impellers for efficiency, while liquids with solids or fibre need open, semi-open, or recessed impeller designs instead.