Sealing issues must be taken into account when selecting chemical process pumps

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Leakage-free operation is the ultimate goal for chemical processing equipment, and it is precisely this requirement that has led to the increasing use of magnetic pumps and shielded pumps. However, there is still a long way to go before true leaklessness can be achieved, such as the lifespan issues of the isolation sleeves in magnetic pumps and shielded pumps, the pitting problems of materials, and the reliability of static seals, among others. Here is a brief introduction to some basic aspects of sealing: 1. Sealing types. For static sealing, there are generally only two types: gaskets and seals, with O-rings being the most commonly used type of seal. In terms of dynamic sealing, chemical pumps rarely use packing seals; instead, mechanical seals are preferred. Mechanical seals can be further divided into single-face and double-face types, as well as balanced and unbalanced types. Balanced mechanical seals are mainly suitable for sealing high-pressure media (typically those with pressures greater than 1.0 MPa). Double-face mechanical seals are appropriate for media that are prone to crystallization, operate at high temperatures, are viscous, contain particles, or are toxic and volatile. An isolation fluid must be injected into the sealing chamber using double-face mechanical seals, and its pressure is usually 0.07–0.1 MPa higher than the pressure of the medium. 2. Sealing materials: Fluororubber is generally used as the material for the static seals of chemical pumps, with polytetrafluoroethylene being used only in special cases. The selection of materials for the rotating and stationary rings in mechanical seals is quite important; it’s not true that one combination of hard alloys is always the best. High costs are one issue, but it’s also unreasonable if there is no difference in hardness between the two materials. Therefore, it’s best to choose the appropriate materials based on the characteristics of the medium being handled. Article source link: http://www.chemhui.com/3713.html