Back-up rings are the most common anti-extrusion devices in dynamic sealing. They provide simple solutions to safely increase system pressure or solve an existing seal extrusion problem. Back-up rings function by positioning a more robust material adjacent to the extrusion gap, taking the seal’s place and providing a barrier against high pressures. Back-up rings can be used to offset the reduced pressure rating effects of wear rings or to improve seal life at increased pressures. They can also be used to protect seals against pressure spikes, or to ensure seal performance at higher temperatures.
Teflon Backup Rings
Supplied by Balaji Seals are available in the following material specifications such as virgin PTFE, which is used mainly for O-rings, Back-up Rings and Spiral Backup Rings are machined parts used in special applications requiring chemical inertness and limited strength. Even they are ideal for use in cryogenic applications.
Bronze filled Teflon 40% & 60% (BFT)
Are used in dynamic sealing applications in manufacture Piston Glyd Rings, Rod Step Seals and Soft Strips where the bronze filler gives improved wear resistance, hardness and compressive strength. The electrical properties and chemical resistance are reduced.
Carbon filled Teflon 15% & 25% (CFT)
Are developed for its mechanical properties. The two basic materials used in these compounds, by themselves, are very questionable. PTFE has good frictional properties including low wear rates and good elasticity. The carbon filler is brittle and has low wear properties. Both fail at high loads and increased velocities. When both elements are formulated and properly blended together, they become an extremely good material for use as seals and rings in the reciprocating compressor industry.
Graphite filled Teflon 15 % & 25% (GRT)
Have significant increased thermal conductivity, reduced level of creep. They are self-lubricating, therefore suitable for high-speed applications, without the need for exterior lubrication and applications, which need to remove thermal energy and/or static electricity.
Glass filled Teflon 15% & 25% (GFT)
Are used, where there is a need for improved wear and increased coefficient of friction. They are ideal for high dynamic applications E.g. High rotation pumps. These high-performance PTFE seals are said to provide exceptional life, high chemical resistance, and lower friction that versus conventional elastomeric seals. PTFE seal handles wide variations in pressure and temperature and surface speeds.