Self-priming pumps are unique. As the name suggests, they can prime themselves under suction lift conditions. They are a type of liquid pump designed to have the liquid inside the cavity or pump body before starting the pumping process. This provides the potential for increased operating efficiencies for a variety of repeated yet infrequent operations.

How does a self-priming pump work?

Self-priming pumps work against gravity by compressing air to get it to move and draw up fluids. These pumps are necessary if it has to be located above the level of the liquid to be pumped. To avoid mixing air and water, self-priming pumps create a partial vacuum to discharge water while evacuating air at the same time. It happens by combining the air and water during the priming process, forcing the water to sink and the air to rise. Gravity pulls the air-free water back into the impeller and mixes with the remaining air in the suction line. This process is repeated until all air is evacuated and a vacuum forms in the suction line. Once this happens, atmospheric pressure forces the water into the suction line and towards the impeller to allow pumping to begin. Self-priming pumps don’t need to be submerged in liquid or located below a water tank. They can operate laterally or above the level of the fluids being drawn through the pump. This makes them easier and safer to work on than those that work below ground. The ability to remain mobile and efficiently operate pumps in varying configurations and environments is perhaps the greatest benefit of self-priming pumps.

What are self-priming pumps used for?

Self-priming pumps are typically used for emptying sumps, so the pump impeller and seal must be suitable for handling these. They are designed to clear the passages of air if it becomes air-bound and resume delivery of the pumpage without requiring outside attention. They will lift fluid from a level below the pump and are capable of evacuating air from the pump suction line without any external devices before beginning their normal pumping functions. Self-priming pumps can be applied to any application where standard self-priming pumps are applied within their hydraulic limitations.

Our WSP™ legacy brand self-primer pump is a rugged and dependable self-priming, solids handling, and trash pump. The WSP Self-Primer pump’s design allows for a shim-less, tool-less impeller adjustment and ease of suction flap valve replacement, with the added benefit of the fill port cover and clamp bar assembly. The recessed bolt-locking construction and anti-rotation design of the clamp bar assembly prevents accidental breach of the fill port cover, protecting the operator.

You can count on our pumps to be field-proven and suited to your specific industry and applications. Our reliable legacy brands, like our WSP™ Self-Primer pump, and our team of dedicated support and services experts ensure you have a trusted partner whose focus is on simplifying maintenance and reducing life cycle costs through innovative design and durability.