Mechanical sealing is a kind of shaft sealing equipment which can maintain the joint and auxiliary sealing performance by two or several inner holes which pull the vertical bisector shaft relative to each other under the working pressure of fluid mechanics and the elastic (or magnetic) effect of compensation organization, which exceeds the leakage resistance

The common mechanical seal structure is composed of static stationary ring (stationary ring) 1, rotating ring (movable ring) 2, elastic element 3, spring seat 4, set screw 5, rotating ring auxiliary seal ring 6 and static stationary ring auxiliary seal ring 8. The anti rotation pin 7 is fixed in the rotating cover 9 to avoid the rotation of static stationary ring. The mechanical seal ring and static stationary stationary ring for rotating kettle can also be used for mechanical seal according to their kettle Whether it has the ability of radial compensation is called compensation ring or compensation return

There are 4 safety channels a, B, C and D in the way of leakage of hydrodynamics in the mechanical seal

C. D leakage safety channel is the sealing between stationary ring and rotating cover, rotating cover and cover respectively, both of which are packing sealing. B safety channel is the sealing between rotating ring and shaft. When the inner hole is damaged by friction, it can only follow the compensation ring moving along the radial direction for micro analysis, but in fact, it is still a relative packing seal. Therefore, this leakage safety channel is relatively speaking It is easy to plug. The most common packing sealing components are vulcanized rubber O-ring or PTFE V-ring. As the rotating ring or stationary stationary ring of compensation ring, sometimes vulcanized rubber, PTFE or metal bellows with the function of elastic components are selected

A safety channel is the dynamic sealing property of the rotating ring and the inner hole of the stationary ring, which is the main sealing property in the mechanical sealing equipment and is important to determine the mechanical sealing characteristics and service life. Therefore, the production and processing of the sealing inner hole are highly regulated, so as to maintain the necessary lubricant film between the sealing inner holes, the total area of the enterprise on the end surface of the cavity system must be strictly controlled If the working pressure is too large, it is not easy to produce a smooth lubricant film, which will accelerate the damage of the inner hole; if the working pressure is too small, the leakage will increase. Therefore, in order to obtain excellent sealing performance and sufficient service life, it is necessary to ensure that the total working pressure of the inner hole enterprise is in the most appropriate range when designing and installing the mechanical seal

The mechanical seal and the soft packing seal have the following advantages: ① the sealing performance is reliable in the long-term operation, the sealing performance is very stable, and the leakage is not large. According to the rough statistical analysis, the leakage is usually only 1 / 150 of the soft packing seal; ② the service life is usually 1-2 years or longer in the oil and water materials, and generally about half a year in the chemical plant materials; ③ friction output The power consumption of the friction output of the small machine seal is only 12% - 60% of that of the soft packing seal;