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Work Pressure On Machinery Seals
Jun 02, 2017

In the selection and use of Machinery Seals should pay attention to the following questions:

  1. Operating pressure

  Seal the operating pressure should be sealed chamber pressure of the sealing medium. Since the chamber pressure is sealed and the Machinery Seals is not equal to the operating pressure of the pump, the pressure of the sealing operation is sometimes higher than or equal to the operating pressure of the pump. Therefore, the working pressure of the seal is determined according to the detailed pump construction type and condition. For example, a single-stage cantilever pump to consider whether the impeller with or without a balanced blade, according to the multi-stage pump-level placement to determine the different seal pressure.

  Usually in the practice of Machinery Seals, the Machinery Seals pressure is higher than 3MPa when the high-pressure Machinery Seals, and the need to choose a balanced seal, more than 15MPa can be multi-level seal and step by step step by step.

  On the pressure exceeds 1MPa when the seal should be considered to eliminate the deformation of the structural type (such as multi-terminal seal, etc.).

  In general, with respect to lubricity and density is higher than the gasoline product seal, in the 0.7MPa below the optional non-balanced seal; also in the value of less than 6.6MPa.m / s use unbalanced seal. On the density of less than 0.6kg / L of the oil are selected balanced seal. On the low viscosity, poor lubrication of the occasion in the 0.2-0.33MPa pressure selection of balanced seal.

  2. Weekly speed

  The circumferential velocity of the sealing surface is usually indicated by the uniform circumferential velocity of the sealing surface. A seal with a peripheral speed higher than 25 m / s is usually considered to be a high-speed seal. For high-speed sealing, a stop seal should be used in order to avoid the effects of centrifugal force and mixing heat. Week speed, pV value is too high, the choice of center ring and other methods to reduce the weekly speed, or the choice of fluid dynamic seal or hydrostatic seal.

  3. temperature

  The operating temperature is usually indicated by the temperature of the media in the sealed box. When the sealing medium temperature is below 80 ℃, the Machinery Seals is usually applicable. On the easy gasification medium, should be considered with the pressure to make the temperature lower than the boiling point of 13.9 ℃, or can not ensure a stable liquid film.

  Usually the medium temperature in the range of 80-150 ℃ for the usual hot goods (Pu heat) sealed, and the temperature above 150 ℃ Machinery Seals for high temperature sealing. As the commonly attached sealing element data will be subject to temperature constraints. A seal below -20 ° C is usually a low temperature seal and a seal below the temperature of -50 ° C is a cryogenic seal. In high and low temperature operation of the seal is not instrument in the data and structure to take a way, and in the auxiliary approach should also have cooling and insulation methods.

  4. Shaft diameter

  Large shaft seal usually refers to the shaft diameter greater than 120mm seal; small shaft diameter seal usually refers to the shaft diameter of less than 25mm seal, during which is usually Machinery Seals.

  5. Media properties

  On the corrosive medium can choose a built-in seal. On the corrosive media due to the elastic components of the selection of tension in the tension is not easy to deal with, optional exterior seal, the pressure is more applicable.

  On the easy crystallization, easy to solidify and high viscosity products, should use a single large tension spring structure, it is more than a few points scattered small tread structure, because it is so easy to plug. For flammable, explosive and toxic products, it is necessary to think about double-ended or cascade or multi-stage seals to ensure that the seal is sure.

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