Water ring vacuum pump mechanical seal leakage reason?

1. Improper mechanical seal assembly
When replacing the non-power end machine seal, it is found in the disassembly process that the sealing o-ring on the moving ring is not installed properly. O type sealing ring should be installed in the sealing groove on the moving ring seat, and the demolition inspection found that O type ring is not so installed, but mistakenly installed in the spring positioning piece, resulting in the spring deformation, completely play the role of axial static seal, resulting in leakage.
2. The sealing cooling water pressure is too high
The binding force of the sealing surface of the dynamic and static ring is exerted by the spring on the moving ring. When the cooling water pressure is too high, the water pressure will act on the rotor and stator ring. Since the stator ring is fixed, the water pressure will push the rotor ring and compress the spring in the opposite direction of the stator ring, so as to weaken or offset the binding force of the rotor and stator ring, resulting in leakage of the sealing surface. Leakage test of cooling water into the machine seal at the power end after overhaul. If the inlet valve is opened less than 2/3, the machine seal is intact without leakage. If the water valve is opened more than 2/3, the machine seal will leak. According to the preliminary judgment, it is caused by the excessive water pressure. It is suggested to start up and use after the motor is repaired to further track and find out the real cause of leakage.
3. The sealing surface of the stationary and static ring is broken
This is caused by the previous several replacement of the pump seal leakage of the main reason. The power end and the non-power end seals are assembled on the same shaft, the impeller is installed in the middle of the shaft, and the two ends of the shaft are fixed with bearings. When the power end or non-power end machine seal is replaced separately, the bearing (bearing seat) at the corresponding end must be removed before the old machine seal can be removed and the new machine seal can be installed. At this time, because of the gravity of the shaft and impeller, the impeller and shaft that have lost one end of the bearing support will inevitably collapse downward and the shaft will tilt towards the non-bearing end. Since the stationary ring with one end not removed is fixed on the pump end cover by bolts, while the stationary ring is fixed on the shaft and rotates together with the shaft. In addition, because the clearance between the inner ring of the stationary ring and the shaft is very small, when the shaft collapses and tilts, it will cause:
A. Relative displacement of the stationary and static ring at the unremoved end makes the sealing surface of the stationary and static ring squeeze each other illegally, causing fracture;
B. the shaft is directly pressed on the inner ring of the unremoved end ring, causing the sealing surface of the static ring to fracture or break.

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