Back-up rings are used with static, as well dynamic applications. However, they have no sealing function.
Extrusion of O-rings or X-Rings under the influence of pressure should be avoided with the back-up ring.
Manufacture of back-up rings in various materials is possible.
- Simple groove geometry
- Easy assembly
- Multitude of materials of construction
- Individual sizes possible
- Bridging of large sealing gaps
- High areas of temperature
- Neutral to fluctuations in temperature
We recommend the use of back-up rings for one or more of the following conditions in service: pressure over 5 MPa (50 bar)
- Larger sealing splits
- Higher stroke frequency
- High temperature fluctuations
- Pulsating pressures
- STR (recommended assembly / mounting sizes for O-rings)
- Back-up rings of the STR series are produced from special polyurethane elastomer through a
special process. The material - hardness 95 shore A - has excellent extrusion resistance.
It is, however, possible to use endlessly manufactured back-up rings for external
sealing applications due to their
memory effect. These back-up rings are meant for automatic assembly. Special
anti-ageing additives in the material are also effective in dry air and oil.
AF-100, 110, 120, 140 and AF-150
Rings of this series are produced by turning, and we recommend specific explanations according to specific applications ( see below)
|STR||endless||internal/external sealing static|
|AF-120||endless||internal/external sealing dynamic|
|STR||slotted||internal/external sealing static|
|AF-110||slotted||internal/external sealing dynamic|
|AF-110||slotted||internal/external sealing static|
|AF-100||spiral||internal/external sealing static|
|AF-100||spiral||internal/external sealing dynamic|
|AF-140||concave (endless)||internal/external sealing static|
|AF-140||concave (endless)||internal/external sealing dynamic|
|AF-150||concave (slotted)||internal/external sealing static|
|AF-150||concave (slotted)||internal/external sealing dynamic|
Material overview for back up rings:
- AF-1012 - Virgin PTFE
- AF-1022 - PTFE with additive
- AF-2426 - PTFE with carbon
- AF-4125 - PTFE with glassfiber
- AF-5640 - PTFE with bronze/additive