Mechanical seal selection-selection according to medium characteristics-

Mechanical seal selection-selection according to the characteristics of the medium

　2017-08-21　　

Mechanical seal selection-selection according to medium characteristics:

For the weakly corrosive medium, the built-in (built-in) mechanical seal is usually selected, and its end face stress state and medium leakage direction are more reasonable than the external (outside-mounted) type. For strong corrosive media, due to the difficulty of spring material selection, external or PTFE bellows mechanical seals can be selected, but generally only suitable for the range of p<0.2~0.3MPa.

For the medium that is easy to crystallize, solidify and high viscosity, a large spring rotating structure should be adopted. Because the small spring is easily blocked by solid objects, high-viscosity media will block the axial compensation movement of the small spring.

For flammable, explosive, and toxic media, in order to ensure that the media does not leak, a double-end structure with a sealing liquid (isolating liquid) or a cartridge mechanical seal should be used.

The structure selected according to the above working parameters and medium characteristics is only a preliminary plan. In the final determination, the characteristics of the host and some special requirements for sealing must also be considered. In the selection of the mechanical seal structure type, in principle, the standard series of seals should be selected as much as possible, but in some cases it cannot be selected according to the conventional selection criteria. For example, the mechanical seals used in petrochemical machinery pumps must be specific The situation is specially designed and necessary auxiliary facilities are adopted at the same time.

See the following two situations for the selection of mechanical seal type for petrochemical machine pumps.

(1) Sealing characteristics, sealing requirements and selection of mechanical seal types under different media or use conditions (Table 2-1);

(2) The working characteristics and measures of typical mechanical pump seals in some process units of oil refining and chemical industry (Table 2-2).

Table 2-1 Sealing characteristics, sealing requirements and selection of mechanical seal types under different media or use conditions

Table 2-2 Working characteristics and measures of typical mechanical pump seals in some process equipment of refining and chemical industry

Manifold non-standard mechanical seal

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Mechanical seal selection-according to the working parameters and shaft diameter selection 　　 cartridge mechanical seal introduction (1)