Mechanical seal is the main cause of leakage of water pump, but mechanical seal itself is a kind of high precision component, which has high requirement for design, machining and assembly quality. In the use of mechanical seals, the use of mechanical seals should be analyzed a variety of factors, so that mechanical seals applicable to a variety of pump technical requirements and the use of media requirements and sufficient lubrication conditions, so as to ensure the long-term reliable seal operation.
Mechanical seals are also known as end-face seals, which have a pair of perpendicular to the rotating axis of the end face, the end of the fluid pressure and compensation mechanical external elasticity, the dependence of the auxiliary seal with the other side to keep fit, and relative sliding, so as to prevent fluid leakage.
Common leakage phenomena
The proportion of leakage of mechanical seals accounted for more than 50% of all maintenance pumps, the operation of mechanical seals directly affect the normal operation of the pump, is summarized as follows.
Periodic leakage
(1) The axial channeling momentum of the pump rotor is large, the auxiliary seal and the interference of the shaft are large, the dynamic ring cannot move flexibly on the shaft. The displacement is not compensated after the pump is turned upside down and the static ring is worn.
Countermeasures: When assembling mechanical seals, the axial channeling momentum of the shaft should be less than 0.1mm, auxiliary seal and shaft interference should be moderate, in the guarantee of radial sealing, the dynamic ring assembly to ensure that the flexible movement of the shaft (the dynamic ring pressure to spring to bounce back freely).
(2) The seal surface lubricant quantity Insufficient causes the dry friction or the NAP seal end face.
Countermeasures: The lubricating oil surface height should be added to the higher than the dynamic, static ring seal surface.
(3) Rotor periodic vibration. The reason is that the stator and upper and lower cover are not in the middle or the impeller and spindle imbalance, cavitation or bearing damage (wear), this situation will shorten the sealing life and produce leakage.
Countermeasures: The above problems can be corrected according to the maintenance standard.
