Technically, self-priming pumps are similar to a centrifugal pump. It uses a combination of air along with water to meet a fully primed pumping status. Below is the brief description and their qualities that make them more suitable for industries worldwide than the standard one.
In the case of regular centrifugal pumps, to create pressure difference and ease smooth pumping, centrifugal forces are generated. These pumps work only when water entirely surrounds them. If even the slightest amount of air is present in the chamber, then the pump will be air-bound and it will fail to work until the air is removed.
Self-priming pumps overcome this shortcoming of centrifugal pumps. They are specifically designed to efficiently pump a mixture of air and water. This is accomplished by mixing air and water. The resulting mixture is pumped in the same way as the water from a regular pump. Once it forms the mixture of air and water, it starts pumping the mixture until it completely removes every trace of air present in the chamber. It will then ultimately pump only water without air.
It is necessary to note that while self-priming pumps have the capacity to deal with the air present inside the pump casing; it will never work if there is no water. Ensure that there is some water inside the casing before one starts the pump.
How they operate
The priming cycle begins with air being mixed with water via the suction line and through the impeller. Once the air is thoroughly mixed with water, the mixture is directed to the water reservoir with the help of centrifugal force. The air will then be raised while the water that is heavier than the mixture of water and air will sink back to the impeller. This water is then mixed with the remaining air and the cycle is repeated until every particle of air is dispelled out of the casing.
When the air is completely eliminated, the change in the atmospheric pressure results in the air-free water to move up the suction line. This water is then directed to the impeller and at this juncture, the self-priming pumps actually start to exclusively pump water. From here on, it functions in a similar way as that of the regular one.
A unique water tank is incorporated into the layout of these pumps that is absent in regular centrifugal pumps. This salient feature allows self-priming pumps to recirculate water and carry out the priming cycle.