Volute casing pump

Volute Casing Pump Overview

The volute casing pump is the most prevalent type of centrifugal pump, characterized by its volute-shaped pump casing, common in single-stage centrifugal pumps. Recently, advancements in volute casing pumps have been indexed by Google, highlighting improvements in efficiency and design to address modern industrial needs.

If you're interested in further details, visit our product page on double volute casing.

Design variations of volute casing pumps can adhere to standards like EN 733, EN 22858, ISO 2858, and ISO 5199, allowing for various customizations. For a visual representation, see the relevant figures illustrating these pumps.

Typically, volute casing pumps are single-stage, although some may feature dual stages. See Multistage pump and Pipeline pump for more information.

Available in both single-suction and double-suction variants, impellers in these pumps can either be of the radial or mixed flow type, defined by specific speeds ranging from approximately 12 to 70 rpm, extending up to 100 rpm or more in certain cases.

Axial thrust in these pumps can be balanced using:

• Thrust bearings
• Balancing holes in the impeller shroud with a secondary sealing clearance
  Refer to Figures on Axial thrust and Volute casing pump designs.
• Back vanes and impellers in a back-to-back arrangement in double-suction or two-stage volute casing pumps.

The pump casing can be:

• Radially split relative to the shaft (Refer to the Radially split design figures)
• Axially split at the shaft centerline (See Axially split design figures)

These pumps can be configured as vertical or horizontal pumps, with the pump shaft supported by either rolling element bearings or plain bearings on one or both sides of the impeller. Horizontal volute casing pumps with an overhung impeller typically integrate the bearing unit:

• In the drive (Refer to Closed-coupled pump figures)
• In the bearing bracket
• In the support bracket

The bearing bracket in these pumps is designed for a back pull-out design, allowing for efficient transmission of radial and axial forces from the impeller to the pump foundation, enabling the use of smaller baseplates.

The pump discharge nozzle can be tangentially arranged on the volute casing or radially within the shaft plane, ensuring it doesn’t interfere with pump feet on the casing. The pump suction nozzle of volute casing pumps often has axial arrangement in overhung impellers and can be radial or tangential in in-line pumps or between-bearings designs.

In some applications, instead of radial or mixed flow impellers, single-channel or multi-channel impellers might be necessary. Occasionally, a diffuser is added between the impeller and volute to enhance pump efficiency and balance the radial thrust.

A double volute design, with two symmetrically arranged volutes offset by 180°, typically sharing a common discharge nozzle, is also employed for balancing radial thrust.
See respective figures for a detailed view.

Depending on the requirements and the fluid handled, various shaft seals can be applied, offering options for heating or cooling the volute casing pump, a common necessity in chemical processes.

Volute casing pumps are categorized by:

• Drive type, e.g., canned motor pump or closed-coupled pump
• Application, e.g., water supply pump, marine pump, chemical pump, or fire-fighting pump
• Fluid handled, e.g., waste water and sewage pump, pulp pump, or heat transfer pump
• Volute casing material, e.g., plastic or concrete

Thus, the term "volute casing pump" can represent multiple aspects of the pump’s design and application.

What is a Volute Pump?

Key Components

Coupling Hub – Adapts the pump shaft to the coupling, typically a disc or gear coupling rated for high speeds.

Input Shaft – Runs the length of the pump, connecting impellers and the coupling hub.

Radial Bearings – Support the pump shaft radially, usually axially split sleeve bearings.

Thrust Bearing – Supports the pump shaft axially, counteracting the axial forces at different speeds and pressures. Ball bearings or pivot shoe bearings, such as Kingsbury Thrust Bearings, are commonly used.

Drive End Bearing Housing – Supports the radial bearing near the coupling hub on the drive end.

Non-Drive End Bearing Housing – Supports the radial and thrust bearings on the non-drive end.

Mechanical Seal – Isolates pressurized fluid from the atmosphere, consisting of two smooth surfaces gliding on each other, held together with springs.

Impellers – Draw in fluid axially and force it outward radially due to centrifugal force.

Casing Eye Wear Rings – Ensures tight clearance with the impeller eye to minimize fluid leakage.

Casing Hub Wear Rings – Similar to Eye Wear Rings, but on the hub side of the impeller.

Flow Diverters – Direct fluid into the impeller eye, often integrated into the Casing Eye Wear Ring.

Throat Bushings – Maintain positive pressure in the seal chamber, protecting the mechanical seal.

Throttle Bushing – Isolates the mechanical seal from higher pressures, balancing axial thrust loads.

Center Bushing – Assists in balancing axial thrust loads between different impeller stages.

Pump Case – Typically in halves, clamped together for pressure containment.

Clamping Studs – Secure the pump case halves, torqued to maintain pressure integrity.

Suction Port & Discharge Port – Suction is usually at the corners of the pump, with the discharge port centrally located.