Back up O-Rings
Back up O-Rings, as the name suggest provide protective and supporting elements made from extrusion resistance material in the O-Ring sealing system. It is designed to fit between the O-Ring and the extrusion gap.
O-Rings tend to extrude into the clearance of mating when subjugated to high temperature and high pressures. Extrusion is the most common type of O-Ring failure cause. Moreover, the combination of high temperature and high pressure extends the hazards of O-Ring failures. In such a case, Back up O-Ring plays an important role in preventing O-Ring extrusions.
Either one or two Back up O-Rings is used to protect the sealing system. This depends upon the pressure of sealing in the sealing applications.
What are Back up O-Rings made of:
The material used in back up O-Rings depends on the requirement of its strength and application. PTFE is generally used for low to medium loads. In case of higher load requirement, filled PTFE (with carbon, bronze or glass fibre) can be used. In addition to these common fills, nylon, PEEK, FEP etcetera can also used. Thermoplasticmaterials are used in case of sealing against high pressure. TFC material is also very well suited for high temperature and high pressure application. In order to prevent abrasion or wear problems, a compatible compound has to be selected with the material of selection
Back up O-Rings are:
- Used in O-Rings with high pressure application
- To prevent O-Rings from gap extrusion in static radial sealing
- In both static and dynamic applications
- In order to balance large temperature variations
- Used in O-Ring material with low hardness
Back up O-Rings are used in wide variety of application like machine tools, excavators, valves for hydraulic circuit, agriculture machines and various others. Back up O-rings thus extends the longevity and increases the efficiency of the sealing applications