Not every centrifugal pump is the same. Different types exist, each designed for specific fluids, flow rates and operating conditions. In this article, we compare the main types of centrifugal pumps based on construction, impeller type and application.

Classification by construction

End suction centrifugal pump

In an end suction centrifugal pump, the suction connection is axial at the end of the pump and the discharge connection is radial on top or at the side. This is the most common type for industrial and municipal use. Features: compact design, suitable for both clear fluids and fluids with solids (depending on impeller type), relatively easy maintenance. The Gorman-Rupp 6400 Series and 6500 Series are examples of end suction centrifugal pumps with a broad application range.

Horizontal centrifugal pump

The shaft is horizontally mounted. This is the standard configuration for most industrial applications. Advantages: easy access for maintenance, good bearing loads and proven reliability.

Multi-stage centrifugal pump

Multiple impellers are mounted in series on the same shaft. Each stage adds head. Suitable for applications requiring high pressures at relatively low flow rates, such as boiler feed and high-pressure water distribution.

Classification by impeller type

Enclosed impeller

The vanes are enclosed between two shrouds. This design minimises internal recirculation and delivers the highest hydraulic efficiency. Suitable for clear fluids and process fluids without large solids. The VG Series uses enclosed impellers with double-curved vanes for maximum efficiency and low NPSH requirements.

Open or semi-open impeller

The vanes are not or only partially enclosed. This makes the impeller more resistant to solids and fibrous material, but efficiency is typically slightly lower. Suitable for wastewater and process streams with a limited amount of solids.

Solids-handling impeller (two-vane or multi-vane)

Specifically designed for pumping fluids with large solids. Two-vane impellers offer a large free passage, while multi-vane impellers provide a better balance between solids handling and head. The 6400 Series offers both options, with solids handling up to 102 mm.

Vortex impeller

The impeller sits recessed in the pump casing and creates a vortex flow. The fluid barely comes into direct contact with the impeller. This makes vortex impellers suitable for extremely fibrous or abrasive fluids, but efficiency is lower than other impeller types.

Choosing the right type for your application

Clear fluids, high efficiency needed? Choose a centrifugal pump with enclosed impeller. The 0 Series is specifically designed for this.

Wastewater with solids and wipes? Choose a pump with solids-handling impeller. The T-series, V-series or 6400 Series with Eradicator technology combines high solids handling with automatic shredding of wipes and fibres.

High flow rates and heads? The 6500 Series delivers capacities up to 3,410 m3/h and heads up to 162 m, with a dual volute that reduces shaft loading.

Contaminated fluids at high pressures? The 80 Series offer efficient handling of lightly contaminated fluids at heads up to 70 m.

Frequently asked questions

Want to know which centrifugal pump best fits your application? Share your application data (flow, head, medium, solids, installation type) and we will advise the right configuration. Contact Gorman-Rupp Europe.

A centrifugal pump is the most widely used pump type in industry, water management and construction. But how does a centrifugal pump actually work, and for which applications is this type most suitable? In this article, we explain the working principle, key components and main application areas, so you can better assess whether a centrifugal pump fits your situation.

What is a centrifugal pump?

A centrifugal pump is a type of pump that moves fluids using centrifugal force. The pump converts rotational energy from a drive (usually an electric motor or diesel engine) into kinetic energy and then into pressure energy, transporting the fluid through the system.

Centrifugal pumps belong to the category of rotodynamic pumps and differ from positive displacement pumps by working with a continuous fluid flow rather than discrete volumes.

How does a centrifugal pump work?

The operation of a centrifugal pump involves three steps.

Step 1: Fluid enters the pump casing. The fluid is directed via the suction connection to the centre (the “eye”) of the rotating impeller. A centrifugal pump does not actively suck fluid in: the rotating impeller creates a pressure reduction on the suction side, causing the atmospheric pressure (or system pressure) to push the fluid towards the pump.

Step 2: The impeller accelerates the fluid. The rotating impeller flings the fluid outward via its vanes. Centrifugal force increases the velocity of the fluid. The vane design (curved, double-curved or straight) determines how efficiently this energy transfer takes place.

Step 3: The pump casing converts velocity into pressure. In the spiral-shaped pump casing (the “volute”), the cross-section gradually increases. This decelerates the fluid and converts kinetic energy into pressure energy. The fluid exits the pump via the discharge connection with sufficient pressure to flow through the piping system.

This operating principle makes centrifugal pumps particularly suitable for applications where large volumes of fluid need to be moved continuously.

Key components of a centrifugal pump

Pump casing (volute): the housing that collects the fluid and converts velocity into pressure. On larger pumps, a dual volute design may be used to reduce radial loads on the shaft.

Impeller: the rotating component that accelerates the fluid. Different impeller types exist: enclosed impellers (for clear fluids and high efficiency), open or semi-open impellers (for fluids with solids), and vortex impellers (for heavy solids applications). The impeller type directly affects efficiency, solids handling capacity and suitability.

Shaft and bearings: the shaft connects the impeller to the drive. The bearings carry radial and axial forces. Oversized bearings significantly extend service life.

Shaft seal: prevents leakage where the shaft enters the pump casing. Common types include packing glands and mechanical seals. For abrasive fluids, cartridge seals are often used for longer service life.

Centrifugal pump applications

Industry: process fluids, cooling water systems, food processing and chemical processes.

Wastewater treatment: pumping wastewater containing solids, wipes and organic material. Robust pumps with high solids handling capacity and self-cleaning mechanisms (such as Eradicator technology) are essential.

Construction and mining: dewatering of excavations, groundwater and water containing sludge.

Water management and municipalities: drinking water distribution, sewage pumping stations and flood control.

Agriculture and irrigation: water supply for irrigation and crop production.

When is a centrifugal pump the right choice?

A centrifugal pump is generally the best choice when dealing with low-viscosity fluids (up to approximately 300 cP), a relatively constant flow rate is needed, and the head fits within the range of the selected pump.

A centrifugal pump is less suitable for high viscosities, strongly varying pressures, or when dosing accuracy is required. In those cases, a positive displacement pump may be a better fit.

Frequently asked questions

Want to know which centrifugal pump best fits your application? Share your application data (flow, head, medium, solids, installation type) and we will advise the right configuration. Contact Gorman-Rupp Europe.

A well-maintained centrifugal pump delivers stable performance for years with low operating costs. Neglect leads to premature wear, unexpected downtime and higher energy costs. In this article, we describe six practical steps for effective centrifugal pump maintenance.

Step 1: Check the shaft seal regularly

The mechanical shaft seal is one of the most vulnerable components. A leaking seal causes fluid loss, contamination and eventually damage to bearings and shaft. What to check: checking the level and condition of the oil, unusual sounds and vibrations, temperature of the seal area. For abrasive fluids, a cartridge seal is preferred. The 6400 Series comes standard with an oil-lubricated, double-floating mechanical seal designed for contaminated media.

Step 2: Monitor the bearings

Bearings carry the rotating forces. Bearing wear manifests as increasing vibrations, temperature rise and audible noise. What to check: bearing housing temperature, vibration level, oil level and quality. Pumps with oversized bearings, such as the 6500 Series, have longer bearing life and require less frequent intervention.

Step 3: Inspect the impeller and wear rings

Wear on the impeller or wear rings increases internal clearance, reducing efficiency and increasing energy consumption. With pumps featuring replaceable wear rings (such as the VGH Series), efficiency can be restored by replacing only the wear rings, without replacing the complete impeller.

Step 4: Check the pump casing

In wastewater applications, fibres, wipes and other materials can accumulate and impede flow. Pumps with an inspection port (such as the 6500 Series) allow checking without full disassembly. Pumps with Eradicator technology (6400 Series) automatically shred wipes and fibres, preventing blockages.

Step 5: Monitor the duty point

A centrifugal pump running consistently outside its optimal operating range wears faster. Too far left on the pump curve causes recirculation and overheating. Too far right causes cavitation and overloading. Variable frequency drives (VFDs) can help maintain the pump within the optimal range.

Step 6: Plan preventive maintenance

Reactive maintenance is always more expensive than preventive maintenance. Recommended schedule: daily/weekly visual checks, monthly bearing temperature and oil level checks, semi-annual seal inspection and wear ring measurement, annual impeller and casing inspection with alignment check.

The interchangeable rotating assembly of the 6400 Series enables replacement on site without dismantling the casing or piping, significantly reducing maintenance time. Gorman-Rupp offers fast delivery of original parts, often within 24 hours.

Frequently asked questions

Want to know which centrifugal pump best fits your application? Share your application data (flow, head, medium, solids, installation type) and we will advise the right configuration. Contact Gorman-Rupp Europe.