Determining the minimum submergence of a pump

The minimum vertical height fluid should have from the suction bells need to avoid production of vortexes is called minimum submergence. A vortex is a tornado or whirlpool-like movement within the water, which can be deep as well, if powerful. The problem of cavitation in the pump can be caused if these vortexes are way too deep.

When air bubbles form and surround the pump's impellers, this phenomenon is known as cavitation. Shockwaves can occur within the pump when these bubbles burst, and these can be severe enough to damage the impeller or other parts of the pump. Therefore, the performance of the pump can be affected. 

The more the liquid is above the inlet, the lesser are the chances of cavitation happening.

For calculating minimum submergence, a simple formula mentioned below can be used:

S=D + (0.574Q / D1.5)

Where:

S = submergence in inches

D = bell diameter in inches

Q = rate of flow in GPM