Principle And Material Of Mechanical Seal

Double cartridge mechanical seal is a rotating shaft with dynamic seal. The mechanical seal has the advantages of reliable performance, small leakage, long service life, low power consumption, without regular maintenance, and can be adapted to the production process automation and the sealing of the harsh conditions of high temperature, low temperature, high pressure, vacuum, high speed as well as various strong corrosive medium, solid particle medium and so on.

A mechanical seal including double cartridge mechanical seal is an axis sealing device that relies on a pair of or several opposite ends of the shaft to be relatively slid on the axis in the fluid pressure and the elastic force (or magnetic force) of the compensatory mechanism.It consists of a moving ring (rotating ring), a static ring, a transmission loading device and a moving and static sealing ring. Because a sealing surface is moving and the other sealing surface is stationary, so this kind of mechanical seal is also called dynamic seal.

There are various types and different types of mechanical seals, but there are five leakage points:(1) the seal between the static ring and the static ring seat; (2) the seal of the seal end cover and the pump body; (3) the seal between the shaft sleeve and the shaft; these three all belong to the static seal. (4) the seal between the ring and the shaft; after the friction and wear of the end face, it can only follow the axial movement along the axial direction of the compensation ring, and in fact it is still a relative static seal. Therefore, these leakage channels are relatively easy to plug. The most commonly used static sealing elements are rubber O ring or polytetrafluoroethylene V ring, while the rotating ring or static ring auxiliary seal is used as compensation ring, and sometimes the structure of rubber, polytetrafluoroethylene or metal bellows with the function of elastic element is used. (5) the dynamic seal of the dynamic ring and the end of the static ring is attached to each other. It is the main seal in the mechanical seal. It is also the key to determine the performance and life of the mechanical seal. Therefore, the processing requirements of the seal face are very high. At the same time, in order to keep the necessary lubricating film between the seal face, the unit area pressure on the end face must be strictly controlled, the pressure is too large and the stable lubricating liquid film is not easy to form, which will accelerate the wear of the end face; the pressure is too small and the leakage amount is increased. Therefore, to obtain good sealing performance and life span, in the design and installation of mechanical seals, must ensure that the end surface unit area pressure value in the most appropriate range.
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