1. During installation and static testing, leakage occurs. After the installation and commissioning of the mechanical seal of the circular arc gear pump, a static test is generally conducted to observe the amount of leakage. If the leakage is small, it is mostly due to problems with the dynamic or static sealing rings; When the leakage is large, it indicates that there is a problem between the dynamic and static ring friction pairs. On the basis of preliminary observation of the leakage amount and determination of the leakage location, manual turning observation is carried out. If there is no significant change in the leakage amount, there is a problem with the static and dynamic sealing rings; If there is a significant change in leakage during turning, it can be concluded that there is a problem with the dynamic and static ring friction pairs; If the leaked medium is sprayed along the axial direction, there are mostly problems with the dynamic ring seal. If the leaked medium is sprayed around or leaked from the water cooling hole, it is mostly due to the failure of the static ring seal.
2. Leakage during trial operation. After static testing, the centrifugal force generated by high-speed rotation during operation of the mechanical seal used in the circular arc pump will suppress the leakage of the medium. Therefore, during the trial operation, mechanical seal leakage is basically caused by the damage of the dynamic and static ring friction pairs after excluding the failure of the shaft to shaft and end cover seals. The main factors causing the failure of friction pair seals are:
(l) During operation, abnormal phenomena such as evacuation, cavitation, and pressure build-up cause significant axial forces, resulting in separation of the contact surfaces between the dynamic and static rings;
(2) Excessive compression during the installation of mechanical seals leads to severe wear and abrasion of the friction pair end face;
(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 static ring seal is too loose, and when the dynamic ring floats axially, the static ring separates from the static ring seat;
(5) There is granular material in the working medium, which enters the friction pair during operation, and detects the sealing end faces of the dynamic and static rings;
(6) Incorrect design selection, low sealing end face pressure ratio, or high cold shrinkage of sealing material. The above phenomenon often occurs during trial operation, and sometimes it can be eliminated by adjusting the static ring seat appropriately, but most of them require disassembly and replacement of the seal.
