Auxiliary seal ring material in mechanical seals
The auxiliary sealing ring of the mechanical seal includes the dynamic ring sealing ring and the static ring sealing ring. According to their functions, the auxiliary sealing ring material is required to have good elasticity, low friction coefficient, resistance to corrosion and swelling of the medium, and aging resistance. There is a small permanent deformation after compression and long-term work. It is non-adhesive when used at high temperature, and it is not hard and brittle at low temperature and loses elasticity. In addition, the material is also required to be convenient to probe and the cost is low.
Auxiliary sealing ring materials mainly use various rubbers, polytetrachloroethylene, etc.
Rubber is a high-elastic polymer compound. Because of its good elasticity and certain strength, when used as a sealing ring, it has a tight seal, excellent cushioning and shock absorption, and has good air tightness, Waterproof, wear-resistant, heat-resistant and corrosion-resistant. Therefore, it is a better sealing material, and it is the most used one in the mechanical seal pumping seal ring.
In addition to the above advantages, the rubber sealing ring can keep the seal within a large tolerance range due to its large elasticity, and it is easy to manufacture. When using different rubber varieties, formula design, mixing and vulcanization processes, products with various properties can be obtained to meet the requirements of different temperature changes, corrosion, dissolution, and swelling of different chemical substances. The shortcomings of rubber sealing rings The friction coefficient is relatively large, and the resistance of the spring is relatively large when it advances forward, which is prone to sticking or aging at high temperatures.
Rubber is divided into natural and synthetic rubber. Auxiliary seals of mechanical seals are generally made of various synthetic rubbers. Different synthetic rubbers have different properties, and it is sometimes necessary to choose which ones to use based on their reasonable properties.
As mentioned above, polytetrachloroethylene is widely used in various temperature, pressure and corrosive media conditions due to its excellent chemical stability, temperature resistance and low friction coefficient. The toughness of the polytetrafluoroethylene O-ring seal can be extracted by quenching, and the dimensional stability of the polytetrafluoroethylene wedge-shaped seal can be improved by filling.
In the case of high temperature, expanded graphite or metal hollow ring is also used as auxiliary sealing ring.