Back-up rings have been used in conjunction with O-rings in high pressure applications. A back-up ring is a rigid ring that holds an elastomeric seal to its designed shape and in its correct place. Back-up rings are most commonly used with O-rings to prevent extrusion at high pressures. When sealing the piston inside a pneumatic cylinder, a soft and flexible material is required to prevent leakage, but those same properties may leave the seal material vulnerable to being pulled out of its seat and then pinched or torn in the narrow space between piston and cylinder wall. If the joint cannot be redesigned, or a more resistant elastomer used, then the solution may be direct reinforcement with a stiffer material - in the form of a hard inner ring in this case. In general terms, for dynamic applications over 100 bar, and static applications around 900 bar, back-up rings should be used. Seal Materials: PTFE (Virgin Teflon). Temperature Range: -50C + 200C Pressure: up to 800 bar (80Mpa) O Ring material: Nitrile, Viton. Size Range : We manufacture PTFE Back up Rings for upto 700mm cylinder bore & Rod diameter as per International Standard Size Chart. Fields of Application : The use of backup ring is must when any of the following operating conditions are present in a hydraulic cylinder. when pressure is above 100 bars (10Mpa). Extreme and frequent pressure variation. Large tolerances between the components to be sealed or large radial sealing gap. High temperatures above 120C.
