Impeller Classification:

Impellers of pumps are categorized based on the number of points in which the liquid could enter the impeller and also on the amount of webbing among the impeller blades.

Impellers could be either single-suction or double-suction. The single-suction impeller permits liquid to enter the middle of the blades from just one direction. A double-suction impeller permits liquid to enter the center of the impeller blades from both sides concurrently. Figure displays simplified diagrams of single and double-suction impellers.

Figure: Single-Suction and Double-Suction Impellers

Impellers could be open, semi-open, or enclosed. An open impeller contains just of blades attached to a hub. A semi-open impeller is constructed along with a circular plate (the web) attached to one side of the blades. An enclosed impeller has circular plates attached to both sides of the blades. The Enclosed impellers are also referred to as shrouded impellers. Figure describes examples of their types open, semi-open, and enclosed impellers.

Figure: Open, Semi-Open, and Enclosed Impellers

The impeller sometimes holds balancing holes which linked the space around the hub to the suction side of the impeller. A balancing hole has a total cross-sectional area which is considerably greater than the cross-sectional area of the annular space among the wearing ring and the hub. The output is suction pressure on both sides of the impeller hub that manages a hydraulic balance of axial thrust.