End suction pumps are one of the most common types of centrifugal pumps. Cost effective and reliable, they are suitable for a range of pumping applications. They are almost always single stage pumps, meaning they have only one impeller.
Available in a wide range of sizes, construction materials and designs, they can be used to pump a variety of fluids from ambient-temperature water, to high-pressure and high-temperature viscous oils, abrasive slurries and corrosive chemicals. Depending on the end pumping application, they can be constructed from plastic, standard iron, hardened iron, stainless steel or more exotic alloys.
End suction pumps can be found across a range of industrial facilities and water treatment and processing plants. They are also commonly used for fire fighting and protection systems, HVAC systems, and for pressure boosting large-scale plumbing systems for large buildings like office buildings, shopping malls and stadiums.
How do they work?
Centrifugal pumps in general work by forcing the pumping fluid through one or more rapidly rotating impellers, thereby increasing the fluid’s velocity and pressure.
End suction pumps usually contain just one impeller and a volute type casing. Volute casings have an offset impeller, which creates a curved funnel with the area increasing towards the pump outlet or discharge. This helps to increase the fluid pressure towards the outlet. The pumped fluid enters the impeller at its rotating axis, or at the eye of the impeller. The fluid is then accelerated by the rotation of the impeller and flows radially outward into the volute casing where the high velocity is converted to high pressure through a diffusion process.
They are normally driven by an alternating current electric motor, though there are direct current motor driven ones available, as well as pumps driven by air motors, hydraulic motors, steam turbines, and diesel and petrol engines.
End suction pumps are available in a few different configurations including close-coupled, frame-mounted and lined pumps.
In close-coupled pumps, the impeller attaches directly to the drive shaft with no separate coupling between them. This means that the pump and the motor never need to be aligned as they are built to fit. There are downsides to this design, however. If a seal fails, there is an increased risk of damage to the motor due to the pump being fitted so closely to the motor. Additionally, repairs can be challenging and expensive since the pump and motor are factory-fitted together. Standard water pumps are typically close coupled.
In a frame-mounted configuration, the pump has its own set of bearings and a coupling separating the pump and motor. These are easier to repair and are more common in heavy industrial applications.
Lined end suction pumps designed for pumping particularly abrasive liquids. These pumps include a replaceable rubber lining that’s designed to wear out and be replaced over time, thereby protecting the more expensive pump components from damage.