Analyze the causes of seal failure of construction machinery seals

Analyze the reasons for the seal failure of construction machinery seals 1． Leakage during static test of the device After the engineering machinery seal device is debugged, a static test is usually carried out to investigate the amount of leakage. If the amount of leakage is small, most of the moving or static ring seals are in doubt; when the amount of leakage is large, it indicates that there is a doubt between the dynamic and static ring conflict pairs. After starting the investigation of the leakage amount and identifying the leakage position, manually crank the investigation. If there is no obvious change in the leakage amount, the static and dynamic ring seals are in doubt; if the leakage amount changes significantly during the cranking, it can be concluded that it is moving, There are doubts about the static ring conflict pair; if the leaking medium erupts along the axial direction, the moving ring sealing ring is mostly questioned. If the leaking medium erupts nearby or leaks from the water cooling hole, the static ring sealing ring is mostly ineffective. In addition, leaky channels can also exist together, but there are usually primary and secondary differences. You only need to investigate thoroughly and understand the layout to be able to determine correctly. 2. Omissions presented during test assignments. After the mechanical seal of the pump undergoes a static test, the centrifugal force generated by high-speed rotation during operation will restrain the leakage of the medium. Therefore, the leakage of the mechanical seal during the trial operation is basically caused by the damage of the dynamic and static ring conflicts after the cleaning of the shafts and the failure of the end cover seal. The main factors that cause the failure of the conflicting pair seal are: during operation, due to abnormal appearances such as flaws, cavitation, pressure holding, etc., a large axial force is caused to separate the contact surfaces of the dynamic and static rings; the amount of tightening when the device is mechanically sealed If it is too large, it will cause severe wear and scratches on the end face of the conflicting pair; if the moving ring seal ring is too tight, the tension spring cannot adjust the axial floating amount of the moving ring; the static ring seal ring is too loose, and when the moving ring floats in the axial direction, the static ring The ring is separated from the static ring seat; there are granular substances in the operating medium, and the conflicts are entered during the operation, and the dynamic and static ring sealing end faces are detected; the planning and selection are wrong, the sealing end face is lower than the pressure or the sealing material has a large cold shrinkage, etc. . The above phenomenon often appears in the test operation of the mechanical seal factory, and sometimes it can be eliminated by proper adjustment of the static ring seat, but most of them need to be disassembled from the beginning to replace the seal. Failure due to the loss of the smooth film on the two sealing end faces: due to the existence of the end face seal load, the pump is started when the seal cavity lacks liquid and a dry conflict occurs; the medium is lower than the full vapor pressure, causing the end face liquid film to flash and lose smoothness ; If the medium is a volatile product, when the mechanical seal cooling system is scaled or blocked, the full vapor pressure of the medium rises due to the end-face conflict and the heat generated by the mixing liquid of the rotating element, and the pressure of the medium is lower than its full vapor pressure. Case.