The mechanical seal is defined by a pair of end face mechanical seal perpendicular to the axis of rotation, and it use the fluid pressure and the elastic compensation mechanism (or force) to keep fit with the mechanical seal. Under the action of the auxiliary seal, and relative sliding, it constitutes a device to prevent the fluid leakage. It is used in centrifugal pump, centrifuge, reaction kettle and compressor. Since the transmission shaft passes through the inside and outside the device, there is a circumferential gap between the shaft and the device, the medium through the device leaks out through the gap. If the pressure inside the device is lower than atmospheric pressure, the air leaks into the device, so there must be a shaft sealing device to stop the leak. There are many kinds of shaft seals, because the mechanical seal has advantages such as low leakage and long life, so the world's mechanical seal is the most important shaft seal in these equipment.

2. The compositions of mechanical seal:

There are four main types of components.

a. The main seal: the moving ring and the static ring.
b. The auxiliary seal: the seal ring.
c. The compression: the spring, push ring.
d. The driving parts: the cartridge and key or fixed screw.

3. The types of mechanical seal:

The rubber bellows seal
The metal Bellows Seal
The O-ring mechanical seal
The PTFE bellows seal
The PTFE wedge ring seal
The single face seal
The double face seal