Leakage cause analysis and judgment:
1. Leakage during installation static test. After the installation and debugging of the mechanical seal, it is generally necessary to conduct a static test and observe the leakage amount. If the leakage is small, it is mostly due to problems with the dynamic or static ring sealing ring; When the leakage is large, it indicates a problem between the dynamic and static friction pairs. On the basis of preliminary observation of the leakage amount and judgment of the leakage location, manually turn the machine to observe. If there is no significant change in the leakage amount, there is a problem with the static and dynamic ring sealing rings; If there is a significant change in leakage during turning, it can be concluded that there is a problem with the friction pair between the dynamic and static rings; If the leaking medium is sprayed along the axial direction, there are mostly problems with the dynamic ring sealing ring. If the leaking medium is sprayed around or leaks out of the water cooling hole, it is mostly due to the failure of the static ring sealing ring. In addition, leakage channels can also exist simultaneously, but there are generally primary and secondary differences. As long as you observe carefully and are familiar with the structure, you can definitely make a correct judgment.
2. Leakage during trial operation. After static testing, the centrifugal force generated by high-speed rotation of the mechanical seal used in the pump will suppress the leakage of the medium. Therefore, during the trial operation, the mechanical seal leakage is basically caused by the damage of the dynamic and static ring friction pairs after eliminating the failure of the shaft to shaft and end cover seals. The main factors that cause the failure of the friction pair seal are: (1) During operation, abnormal phenomena such as evacuation, cavitation, and pressure suppression cause significant axial force, causing separation of the contact surface between the dynamic and static rings; (2) Excessive compression during the installation of mechanical seals leads to severe wear and scratches on the end face of the friction pair; (3) The sealing ring of the moving ring is too tight, and the spring cannot adjust the axial floating amount of the moving ring; (4) The sealing ring of the static ring is too loose, and when the dynamic ring floats axially, the static ring detaches from the static ring seat; (5) There are granular substances in the working medium, and friction pairs are introduced during operation to detect the sealing end faces of the dynamic and static rings; (6) Incorrect design selection, low specific pressure of the sealing end face or high cold shrinkage of the sealing material. The above phenomena often occur during trial operation, and can sometimes be eliminated by adjusting the static ring seat appropriately, but most require disassembly and replacement of the seal.