In this module, we’ll explore what end suction pumps are, their key components, and the different pump types available. Let’s get started.

What is an end suction pump? An end suction pump is a horizontal, single-stage centrifugal pump. Liquid enters the centre of the impeller and is discharged through the top outlet. The main features of end suction pumps include:

A single-stage impeller design

Cast volute for strength and durability

Back pull-out construction for easy servicing

These features make end suction pumps reliable, versatile, and cost-effective, which contributes to their widespread use around the globe.

To ensure proper selection, installation, troubleshooting, and maintenance of end suction pumps, it’s essential to understand their key components. Let’s take a closer look.

Pump casing or volute: The casing houses the impeller and converts kinetic energy into pressure. It’s usually made from cast iron, ductile iron, or stainless steel depending on the fluid.

Impeller: This is the rotating part that transfers energy to the fluid. Depending on the required flow, pressure, and fluid type, … impellers can be open, semi-open, or enclosed.

Shaft: The shaft connects the impeller to the motor.

Coupling: These transfer torque from the motor to the shaft, allowing the impeller to turn.

Seal: The mechanical seal prevents leakage along the shaft where it exits the casing.

Modern designs often use silicon carbide seal face materials to ensure long service life, especially with abrasive liquids.

Motor stool: This connects the pump casing to the motor in split-coupled and close-coupled pumps, keeping the motor and pump aligned. It also allows the motor to be easily removed for maintenance.

Bearings: These support the rotating shafts of the pump and motor, ensuring smooth operation, reduced vibration, and longer pump life.

Baseplate: This provides structural support and keeps the pump and the motor aligned. When installed correctly, it absorbs loads, reduces vibration, and protects long-term shaft alignment.

Some designs also allow for easy seal access and back pull-out without disturbing the piping.

Motor: The motor is also referred to as the driver because it provides the driving power.

Grundfos often integrates motors with a variable frequency drive (VFD) for advanced control and improved energy efficiency, as the VFD adapts pump speed to system demand.

Each of these components plays a crucial role. Understanding them helps ensure the pump is selected and configured correctly for its intended application. Now let’s look at the types of end suction pumps.

There are three main types:

Close-coupled

Split-coupled

Long-coupled

Let’s take a closer look at each.

Close-coupled pumps are the most compact. They eliminate the need for a separate coupling because the impeller mounts directly onto the motor shaft or via a stub shaft. This saves space and removes alignment requirements. Their back pull-out design reduces initial cost and simplifies installation and servicing without disturbing the piping.

Split-coupled pumps use a rigid split coupling and motor adapter for precise alignment. The coupling design removes the need for laser alignment and simplifies installation.

By using the motor bearing to support the pump shaft and impeller, split-coupled pumps reduce footprint by around 35% compared with long-coupled pumps, while maintaining similar flow and pressure performance.

Long-coupled pumps use a flexible coupling and a dedicated bearing bracket, making them suitable for high-pressure or high-temperature duties.

Mounted on a rigid baseplate, they are easy to transport and install. Their back pull-out design, together with an optional spacer coupling, also allows servicing without disturbing the pump, piping, or motor.

That covers our overview of end suction pumps: what they are, their key components, and the different pump types available. In the next module, we’ll explore the Grundfos NB, NBS, NK end suction series and their performance characteristics.