Dual Seal


In the past, the terms double and tandem seals were used to describe the popular methods of installing two seals in a pump. “Dual seal” is the better term to use when you are describing two seals.

The two seals can be installed in four separate configurations.

I am showing the rotating version of the dual seals in these diagrams, but you should be aware that a stationary version of each of these seals is also available from most seal suppliers:

Rotating, back to back designs are the least desirable.
Tandem designs take a lot of axial room, but they are the most popular in oil refineries
Face to face designs require very little axial space, but the two seals often share a common stationary face that if broken, would fail both seals.
The concentric seal take very little axial space, but require a lot of radial room.


Their application is often limited to mixers that have very little room between the top of the mixer and a coupling.

Convection tanks are often used to contain the fluid between dual seals.



  • On February 15, 2018