This is exactly the purpose of a mechanical seal, to prevent fluid leakage on a rotating body, therefore on a seal where there is an impeller which puts the water under pressure.

How is a mechanical seal made? The mechanical seal is basically composed of two parts, one fixed and one mobile rotating. The fixed part is mounted on the pump body, is sealed by an external O-ring and has a ground and polished face which contacts the moving part.

The moving part is mounted on the shaft, and is therefore integral with it. The seal is also made in this case with an O-ring, a classic seal therefore, on the shaft seat. The seal between the two parts is ensured by the contact between the two faces, which, being ground and very smooth, prevent any liquid leakage, whether it be water or oil.

The construction materials of a mechanical seal are therefore different, according to both the type of fluid that is moved and the working temperatures involved. Depending on the fluid handled, and as temperatures rise, for example with the use of oil or aggressive fluids, the seal materials must in fact guarantee the right resistance.