Reasons Why Your Self-Priming Pump Won’t Prime

Self-priming pumps are used in most applications in which a centrifugal pump can be used. The difference between a self-priming pump and other types of centrifugal pumps is the pump’s ability to prime itself.

If your self-priming pump is failing to prime, there are a few different factors that could be affecting it. Here we will discuss some of those factors that could stop your self-priming pump from priming properly.

How Does The Self-Priming Pump Work?

A self-priming pump is created with an external type of casing. This casing will flood the inner pump. When this happens, the centrifugal pump turns on. This initiates the impeller to rotate counterclockwise which then creates a low-pressure area at the center of the propeller. This low pressure is lower than the atmosphere. Water is then pushed inside the suction pipe, causing all of the air in the line to then pump. By mixing air with the water, the pump can prime itself.

Why Is The Self-Priming Pump Not Priming?

Let’s look at a few things that can cause your self-priming pump to not prime properly.

Leak in the suction line – It is necessary for the suction line to be air-tight for the prime to work properly. If there is a leak in the suction line, then the pressure will not be able to build properly to initiate the prime.

Debris in the impeller – Debris located near the center of the impeller can also affect the hydraulic function of the pump. This will prevent the impeller from making a low-pressure area, stopping the pump from performing as it should.

Air bound pump – If the pump becomes filled with air, then a vacuum cannot be properly created, and the pump will not prime.

Too much clearance between the impeller and the wear plate – This could be caused by wear or a reassembly that was done improperly.

Blocked recirculation port – If anything plugs this port, the proper flow of water cannot be created.

Undersized pump – If your pump is not properly sized for the suction line, the proper flow cannot be maintained.

What To Do?

If you are experiencing any of these self-priming pump issues, it is important to remember this is not necessarily a DIY project.

Bringing in a professional is the best way to solve problems with your self-priming pump. If you are unsure how to repair your pump, you could do worse damage trying to do the job yourself.    

Categorised in: Vacuum Prime Pumps