Mechanical seal is very important. Most of the failures of many product R & D products are due to ineffective or ineffective sealing. What's the reason for the ineffective sealing function of mechanical seal? Tianjin mechanical seal manufacturer will give a detailed description for you.

1、 Protuberance opening

In the repair of mechanical seals, 86% of sealing invalidity is not caused by damage, but has been leaked before damage. When the protrusion surface is opened, the liquid particles in the material enter the protrusion surface under the action of the working pressure of the liquid. After the protrusion surface is closed, the liquid particles are placed on the surface of the soft ring, which in fact becomes a "sand wheel piece" that will destroy the surface of the hard ring.

Because the moving ring or silicon rubber ring is screwed on the shaft (sleeve), when the shaft moves in series, the moving ring can not immediately fit the machine, and then the protruding surface is opened, and the protruding surface is backward and closed, so that the liquid particles enter the protruding surface.

There are also liquid particles in the middle of a shaft (shaft sleeve) and a driving component, endangering the driving of silicon rubber ring or moving ring (relative dynamic sealing point, mechanical failure). On the other hand, the substances will also create crystals at the friction position between the silicon rubber ring and the shaft (shaft sleeve), and there will also be liquid chemicals at the elastic yellow place, all of which make the protruding surface open. Mechanical seal

2、 Overtemperature

Due to the heat caused by the protruding surface, the application temperature of silicon rubber ring shall be lower than the design standard. The application temperature of fluororubber and PTFE is 218 ℃ and that of NBR is 164 ℃. Although both of them can bear higher temperature and do not cause higher heat due to protruding surface, the silicone rubber ring has the risk of re vulcanization of rubber and finally loss of ductility and leakage.

In the middle of the protrusion, the heat will also cause the crystal of the material, such as carbon deposition, which will cause the drag component to be stuck and the protrusion to be solidified. In addition, some polymers are over heated in coking plants, and some hydrodynamics is over heated, resulting in loss of wetting and even flash fire.

Overtemperature can not only change the condition of substance, but also increase its corrosion rate. In order to reduce the specific pressure and avoid overtemperature, the balanced mechanical seal should be used in the design scheme to cause the deformation of metal parts, the crack of aluminum alloy surface and some coating gaps.

3、 Deviation

Proper tolerance of assembly line dimension is very necessary for the installation of machine seal. The shaft (shaft sleeve) must have suitable roughness and proper specification, but the manufacturer seldom presents the statistical data of dimensional tolerance, which is very important for the installation.

The specification precision and dimension tolerance of mechanical seal must meet the requirements of engineering drawing. Deviation will lead to early invalidation of sealing.