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Contact Machinery Seals Problems
Sep 21, 2017

    With the development of modern industrial production, the Machinery Seals of the working environment more stringent, the sealing performance requirements such as sealing, safety, reliability and so on. At present, domestic and foreign rotary pump (mainly centrifugal pump) with a Machinery Seals is basically a common contact Machinery Seals, due to the existence of direct sealing between the sealing surface wear, resulting in sealing due to the surface friction temperature rise is too high, excessive Wear and other reasons early failure. In the sealing environment is more harsh conditions, such as sealing easy to vaporization class, high risk, high corrosive, high solid particle medium, high pv value of the work conditions, there are a lot of liquid phase leakage and gas phase escape and pollute the environment , Sealing reliability and stability greatly reduced, the probability of failure increased significantly, it is difficult to meet the long-term operation, pollution, low energy consumption and other modern industrial production of the objective requirements.

    The defects of the contact Machinery Seals are mainly reflected in the following aspects:

    (1) sealed media prone to leakage, resulting in material damage and environmental pollution.

    Sealing principle: in the sealed fluid and the outside there is a pressure difference [generally higher than the pressure outside the pressure) under the premise, by maintaining a certain end contact pressure, as far as possible to reduce the sealing friction between the end of the axial clearance to reduce Leaked by sealed fluid. It can be seen that the contact Machinery Seals is difficult to achieve zero leakage of the sealed fluid, and it is impossible to achieve its zero escape. With the continuous improvement of modern environmental requirements, the application of ordinary contact Machinery Seals will be more and more restrictions.

    (2) sealing the existence of friction and wear, short service life.

    There is a direct solid friction and wear between the sealing friction pairs, and the accumulated result must be limited in the service life of the seal.

    In general, the life of a conventional contact Machinery Seals is not more than one year, and for some poorly lubricated sealed fluids or sealed fluid containing a certain amount of solid particles, the seal has a service life of only a few months or even days.

    (3) sealed working state is unstable, the probability of failure greatly increased.

    The friction temperature between the sealing end faces has a great influence on the working condition of the sealing friction pair, and it is possible to vaporize the liquid film of the end face (that is, phase change, especially for the vaporized medium such as high temperature oil pump, hot water pump, Etc.), from single-phase lubrication into vapor-liquid mixed-phase lubrication, so that the seal friction in an unstable working state, resulting in "tweet", "steam injection" phenomenon, the probability of failure greatly increased.

    (4) seals produce thermal deformation, hot cracking, hot and failure.

    The rapid temperature rise between the sealing end may also lead to excessive temperature rise of the seal ring to produce a large thermal deformation, friction and wear serious, so that the mechanical properties of the sealing material is reduced, easy to seal ring (mainly hard ring) Hot crack, auxiliary sealing ring to produce hot, aging and so on leaving the seal early failure.

    Machinery Seals failure records found a considerable proportion is due to the sealing end of the temperature rise caused by high.

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