What problems may be encountered when using mechanical seals for slurry pumps

The mechanical seal of the slurry pump can be used without external flushing water, and can adapt to various media at room temperature. The external high pressure (pressure greater than the pump chamber pressure, flow rate 0.5L/s) of the mechanical seal will enter the pump chamber and dilute the pump chamber. The conveyed medium makes the seal have a long service life, and a static test should be carried out to observe the leakage. If the leakage is small, it is mostly due to the problem of the dynamic ring or the static ring sealing ring. When the leakage is large, it indicates that there is a problem between the friction pair of the dynamic and static rings. On the basis of the initial observation of the leakage amount and the judgment of the leakage location, and then manual crank observation, if there is no obvious change in the leakage amount, there is a problem with the static and dynamic ring seals. If it is sprayed along the axial direction, there are many problems with the moving ring sealing ring. If the leakage medium is sprayed around or leaks out from the water cooling hole, the static ring sealing ring is mostly invalid. Leakage channels can also exist at the same time, but there are generally primary and secondary differences. As long as you observe carefully and are familiar with the structure, you will be able to judge correctly. Most of the leakage at the sealing point of the static ring is caused by the defects of the mechanical sealing ring of the slurry pump, such as the size error of the sealing ring is too large or the seal itself is damaged, aging and so on. As long as the design structure and material selection are correct, the sealing ring has been carefully checked, and the static seal is carefully installed, the quality can be guaranteed. The vibration of the seal is too large, but the reason for the large vibration of the seal is often not the cause of the vacuum pump itself. The unreasonable design and installation of other parts of the pump are the root causes of the vibration, such as the unreasonable design of the pump shaft, the reasons for the processing quality, the insufficient bearing accuracy, Poor parallelism of the coupling, large radial force, cavitation and other reasons will cause the mechanical seal to vibrate too much. The sealing surface is pitted or even penetrated. Due to the welding problem between the tungsten carbide ring and the stainless steel seat, the stainless steel seat is prone to intergranular corrosion during use. Welded metal bellows, springs, etc. are prone to rupture under the combined action of stress and medium corrosion. Thermal cracking is a common failure phenomenon of high-temperature oil pumps, such as frying pumps, oil return pumps, atmospheric and vacuum tower bottom pumps. When the sealing surface is in dry friction, the cooling water is suddenly interrupted, impurities enter the sealing surface, evacuation, etc., radial cracks will appear on the annular surface. Graphite carbonization is one of the main reasons for the failure of the seal when using carbon-graphite rings. In use, if the graphite ring exceeds the allowable temperature, resin will precipitate on its surface, and the resin near the friction surface will be carbonized. When there is a binder, it will foam and soften, which will increase the leakage of the sealing surface. After the action temperature is exceeded, it will rapidly age, crack, harden and lose elasticity.