Clacification of Mechanical Seal

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Clacification of Mechanical Seal

Mechanical Seal are classified as follow:



Balance & Unbalance

Balanced seal


  • Used for pressures greater than 150 psi 
  • Balance Ratio = Ac/Ao  < 1  
  • Always recommended for volatile liquids     

Unbalanced seal

 

  1. Used for pressures greater than 150 psi
  2. Balance Ratio =Ac/Ao  ≥ 1
  3. Not recommended for volatile liquids

The ratio between the forces which are closing the seal ring and the ones which are opening the seal ring is called as the “Balancing ratio".


Pusher seal

  1. Pusher seals utilize one or multiple springs to maintain seal closing forces

  2. Ideally suited high pressure but not suitable for high temperature applications.

  3. A drawback due to the elastomer under the primary seal face that can be subjected to wear


Pusher Mechanical Seal

Non pusher

  1. Non-pusher seals utilize a metal or elastomeric bellows to maintain seal closing forces

  2. Ideally suited to dirty and high temperature applications but not suitable for high pressure applications

  3. Bellows seals are limited to medium/lower pressure applications. 


Type GL1B Metal Bellows Seals | Pump Seals | John Crane
Non Pusher Seal

  • Inside Mounted 



    Rotating seal member present at the pump side


  • Outside Mounted

     Rotating seal member present at the atmospheric side


In the next Section we will discuss about Double Mechanical seal

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