Mechanical Face Seals, also known as Heavy Duty Seals, Duo-Cone Seals or Toric Seals are of two types: one is SDO type which consists of two profi led metal rings along with two energizer O-Rings and the other is the SDM type, which also consists of two L-shaped metal rings along with a profi led diamond shaped energizer. The metal rings are assembled in the housings, which has a relative rotary motion between them. Sealing action is in between these metal rings, whose mating faces are ground and lapped. Only one half of the seal rotates, and the seal faces are kept in contact with a predetermined axial load with the help of these energizers. Mechanical Face seals, due to its robust construction and materials used, off ers a longer life, compared to other possibilities for the same applica- tion, which are tough to be sealed in normal course. These seals are thus mostly used in dirty or rough & adverse environments. The SDO type calls for a specially machined profi le even in the housing cavity, whereas the SDM fi ts into an easy to make square bore.