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.
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.