Regarding the determination of the mechanical seal for centrifugal pumps? Determination of sealing pressure?
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Dear experts at RT, how should one determine whether to choose a mechanical seal with balance or without it? Is it based on the sealing pressure? Then how should the sealing pressure be determined? I’ve looked up some information, and it says that it varies depending on the type of pump. Floating by gently~ Thank you all..
For pumping process media with process pumps, balanced mechanical seals are primarily used. In applications such as those involving clean water, where the head is less than 50 meters and the inlet pressure is not high with minimal fluctuations, unbalanced mechanical seals can also be employed. The pressure in the sealed chamber is generally equal to the inlet pressure plus the pressure corresponding to the head, multiplied by a certain coefficient; this coefficient varies depending on the type of pump – pumps with balance holes or back impellers have different coefficients. In most cases, this coefficient ranges between 0.1 and 0.3.
This post was last edited by bage on 2011-12-23 21:10. Currently, the mechanical seals used in most centrifugal pumps in chemical and refining plants are of the balanced type; some seals with smaller shaft diameters are designed as unbalanced types, and those cases mentioned by the brother in floor 2 are also implemented as unbalanced types. . As for the pressure in the sealing chamber, it varies among different pump types, but most pumps (especially those newly designed in recent years) strive to keep this pressure low, generally 1–2 kilograms higher than the pressure at the pump inlet. It should be noted that the pressure in the outlet seal chamber of some earlier-designed two-stage pumps is relatively high; care should be taken if external flushing is required.