Backup rings for O-Rings are used to restrict extrusion and destruction of the O-Ring. See the diagram for more details.
- The cross section of an O-Ring is deformed diametrically on fitting and all irregularities in the faces are evened out by resilience.
- Under the pressure of medium, the O-Ring is deformed in the direction of the gap between the parts, thereby improving the effect.
- When certain limiting conditions are reached, the O-Ring is pressed into the gap.
- If pressure increases further, the O-Ring is destroyed by extrusion.
- The “extrusion” is significantly dependent upon the pressure level, the size of the gap between the two faces and the hardness of the O-Ring. To restrict extrusion, a Back-up ring is used.
KOK Back-up Rings are available in Polyamide or PTFE.
