How to Solve the Leak of Mechanical Seal of Water Pump

1. Leakage due to pressure

Mechanical seal leakage pump caused by vacuum operation. During start-up and shut-down, due to the clogged pump inlet and the pumping medium containing gas, negative pressure may occur in the sealed chamber. If the pressure inside the sealed chamber is negative, it will cause dry friction on the sealed end face, and the built-in type mechanical seal will cause leakage (water) phenomenon. The difference between the vacuum seal and the positive pressure seal is the difference in the directionality of the sealing object, and the mechanical seal also has its adaptability in a certain direction.

The solution is to use double-sided mechanical seals. This helps to improve the lubrication conditions and improve the sealing performance.

2. Leakage due to medium

(1) After the mechanical seals of most submersible pumps are dismantled, under the auxiliary seals of the stationary ring and the moving ring, some of them have rotted, resulting in a large amount of leakage of the machine seal and even the phenomenon of shaft grinding. Due to the corrosive effect of high temperature, weak acid and weak alkali in the sewage on the static ring and the auxiliary ring rubber seal, the mechanical leakage is too large. The dynamic and static ring rubber seal material is nitrile--40, which is not resistant to high temperature, and is not resistant to acid and alkali. It is easy to corrode when the sewage is acidic and alkaline.

The solution is to corrosive media, rubber parts should use high temperature resistant, weak acid, weak base fluororubber.
(2) Leakage of mechanical seal caused by solid particle impurities. If the particles enter the sealing end face, they will scratch or accelerate the wear of the sealing face. The accumulation rate of scale and oil on the surface of the shaft (set) exceeds the wear rate of the friction pair, so that the moving ring cannot compensate wear displacement, and hard to hard friction. The operating life of the secondary is longer than that of the hard-to-graphite friction pair, since the particles of the perimeter will be embedded in the sealing surface of the graphite seal ring.

The solution method is to use a tungsten carbide-to-tungsten carbide friction seal in the place where solid particles can easily enter.

3. Leakage of mechanical seal due to other problems

Mechanical seals also have places that are not reasonably designed, selected, installed, and so on.

(1) The amount of spring compression must be carried out according to regulations. It is not allowed to have excessive or too small phenomenon. The error is 2mm. Excessive compression increases the pressure ratio at the end face, resulting in excessive frictional heat, resulting in thermal deformation of the sealing surface and acceleration of the end face. When the compression amount is too small, the specific pressure of the end face of the movable and stationary ring is insufficient, and it cannot be sealed.
(2) Install the end face of the shaft (or sleeve) of the dynamic ring seal ring and the end face of the seal gland (or housing) on which the static ring seal is installed. Be sure to chamfer and repair the light so as not to damage the static and dynamic ring seal during assembly.