What should be paid attention to when using mechanical seals under low temperature conditions
Under the low temperature environment, it is easy to cause the leakage of the mechanical seal due to the poor fit of the cross-section. Therefore, for the low temperature seal, in addition to selecting the appropriate auxiliary sealing ring material, the following issues should also be paid attention to.
1. Improve the sealing structure and correctly select the friction pair material. Practice has proved that opening a circular arc groove on the surface of the static ring can form a hydrodynamic seal, increase the bearing capacity of the fluid film, improve the lubrication conditions of the end face, and effectively prolong the working life of the mechanical seal. In terms of end-face pairing, tungsten carbide-M106K graphite pair (ie, dynamic and static ring materials) is generally better than other materials, because of its good lubricity, low friction coefficient, and better thermal conductivity.
2. Select the appropriate end face specific pressure. Due to the poor lubricity of the end face of the low temperature seal, it is easy to gasify and freeze, so on the premise of ensuring the reliability of the seal, the specific pressure of the end face can be appropriately reduced. Generally, the specific pressure value of mechanical seal is recommended to be 0.29-0.59MPa, and the lower limit can be selected for low temperature seal. For metal bellows mechanical seals, since the moving ring has no axial friction, the end face specific pressure can even be lower than the lower limit.
3. Take corresponding measures in the process. For example, reduce the water content of the medium as much as possible; keep the pressure of the sealing chamber relatively stable; be equipped with a flushing cooling device as much as possible; properly preheat the sealing part before the equipment is started.
When using mechanical seals under low temperature conditions, some corresponding protective measures must be taken to avoid leakage, damage and other problems, which will affect the use effect.