Mechanical Face Seal Type 76.90H/97H

Construction

Mechanical face seal type 76.90H/76.97H consists of two geometrically identical metallic seal rings, located against the respective housing bores by means of large-volume O-rings.

At installation, the O-rings lodged between the tapered contact faces of the seal ring and housing undergo a defined deformation which is crucial for permanent operation of the sealing system (dimension “A”).

Working Principle

The resilience of the O-rings acts in a number of ways:

• it exerts an axial load on the metallic sealing faces
• transmits the frictional torque to the housing components
• and provides a static seal between each seal ring and its housing bore

The seal faces of the metallic rings are lapped to a radial width of about 2.5mm and are therefore finely tuned to one another from early life.

The rings are designed in such a way that they open out from the seal faces towards the centre axis, forming a wedge-shaped gap which has the following benefits:

• the lubricant is readily admitted to the seal faces by capillary action and centrifugal force
• adequate lubrication and cooling are assured and potential cold welding of the seal faces is avoided
• as wear increases, the sealing face graduates towards the centre axis; the seal therefore has large wear reserves which virtually only end when the inside diameter is reached
• the traces of lubricant visible at the outer gap indicate that the seal is optimally constructed and is working perfectly