mechanical seal in pump

The use of mechanical seal in pump

In the simple terms, a mechanical seal is a method of preventing the fluid from leaking through a vessel (in this context it is a pump or mixer) where the rotating shaft passes through a stationary housing.

In some scenarios, the housing also rotates around the shaft.

If we consider the scenario of a centrifugal pump, then it is further challenging as the rotating shaft enters the wet area. Hence, the fluid has to be prevented from leaking out when the volume and pressure of the fluid are pretty high.

Hence, some efficient sealing mechanism is needed between the pump housing and the shaft. This mechanism should withstand the pressure of the process and the fraction due to the rotation of the shaft.

The conventional seal

The conventional methods such as braided packing have been replaced by mechanical seals.

What is a Braided Packing? Gland packing is a type of braided packing where a rope like material is used for packing the surrounding area of the shaft. The gap between the pump housing and the shaft is stuffed to prevent the leakage.

Though it is still used in many applications, the popularity trend shows a decline because of several reasons:

  • Due to the friction, there is a constant wear and tear of the packing. It requires frequent readjustment of the packing to prevent leakage.
  • Since there is a high friction, the packing has to be kept cool by flushing large quantity of water.
  • The pump requires more drive power to turn the shaft because of high friction. It means, there is a big loss of energy.
  • The grooves of the shaft get worn out due to the friction. Repair and maintenance of the shaft is a costly affair.

Mechanical seal, the right choice

Mechanical seals eliminate all the drawbacks of braid seals. In a typical mechanical seal, there are three sealing points:

  1. The stationary part which is fitted to the housing of the pump with the help of a static seal. Normally, O-ring or gasket is used for it which is clamped between the stationary and moving part to achieve sealing.
  2. The rotary part or moving part of the seal. Using an O-ring, it is sealed on the shaft. Since the sealing point also rotates with the shaft, it can be regarded as static part.
  3. The mechanical seal is considered the interface between the rotary and static parts of the machine.

In the mechanical seal, one of the two portions (the rotary and static) is spring loaded and solidly mounted so that it can withstand the shaft movements and deflections.

The deflections occur because of the bearing tolerances or out-of-perpendicular alignment which is a result of manufacturing tolerances.

Benefits of using mechanical seals

  • No damage to the sleeve or pump shaft.
  • Reduced maintenance requirement.
  • Less power required than gland packing.
  • Less corrosion
  • Cost-saving

Due to excellent work efficiency, mechanical seals have become quite popular, and they have replaced the old-styled methods.

Leak-Pack specialize in providing solutions to all types of leakages by manufacturing Mechanical Seals and Sealing Components as per customer’s drawings, samples or requirements. To know more about Mechanical Seal call on +91-(2739) 271592 or email at

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