What are Mechanical Seals?

Posted by BMG on October 25th, 2022

Industry experts consider it to be a method by which fluids are contained within a vessel, usually mixers, pumps, etc. In this type, there is passed a rotating shaft via the stationary housing or perhaps at the place where housing tends to rotate surrounding the shaft. The challenge faced while sealing centrifugal pump is to permit the rotating shaft to get into the pump’s ‘wet’ area.

Addressing challenges

However, in this process, pressurized fluid is not allowed to escape in large volumes. Hence, to overcome this particular challenge a seal will have to be fitted between the pump housing and the shaft. This way, process pressure can be properly contained of that being pumped. It also helps withstand friction resulting from shaft rotation. It will be essential to know the details to overcome such challenges and ensure efficiency.


Basically, Mechanical seals can be found to have three sealing points. The seal’s stationary part gets fitted to pump housing using a static seal. Gasket or o-ring may be used to seal it by clamping them between pump housing and the stationary part. The seal’s rotary portion gets sealed with an O-ring onto the shaft. This particular sealing point is considered to be static since this seal part tends to rotate with shaft.

Considering other aspects

Seal is stated to be the interface between its rotary and static portions. A particular part of it, either rotary or static portion is mounted resiliently as well as spring loaded. The objective is to accommodate shaft movement and deflections that otherwise results from bearing tolerances. Moreover, out-of-perpendicular alignment may be caused by manufacturing tolerances. Thorough research will be essential to know about pneumatic seals before investing in them.

Why use them?

There are cited several reasons for this product being commonly used. Seals generally leak vapour since fluid film on faces tends to reach seals faces’ atmospheric side. At normal operating temperatures and pressure, it is likely to be ½ tsp a day, in condensed form. Seals tend to have inboard springs that cause them to self-adjust with wear and tear. Hence, regular maintenance is desired. Modern cartridge designs are not found to cause any kind of damage to the sleeve or pump shaft.

Other reasons for its increasing popularity

In normal operation, bearing contamination gets reduced since lubricant is not affected due to wash out and seal leakage. Seals come with lightly loaded faces, thus consuming less power when compared to gland packing. Using this technology, it is possible to seal vacuum. Less corrosion problems are experienced by the plant equipment if product can be contained within the pump. The fact is that less wasted product will result in huge savings. You should discuss with the industry experts about your business and they can help guide you to make the right selection.

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