Back-up ring - BU3 (spiral)

PTFE (Polytetrafluoroethylene) is a synthetic fluoropolymer of tetrafluoroethylene, also known under the trade name Teflon®*.
Back-up rings BU3 are primarily used in combination with O-rings to support the O-rings from extrusion. The back-up rings BU3 reduce the gap and prevent the O-ring from being pushed into the gap and damaged. This back-up type is often used in closed grooves where uncut back-up rings are unsuitable.
Back-up rings allow O-rings to run in high pressure applications, and they can be used both in static and dynamic applications. Back-up rings are cheap and simple sealing elements with a very wide area of application in hydraulic and pneumatic systems.

PROFILE


Spiral back-up ring with slit (cut).
 

PRODUCT ADVANTAGES
• Can be used both for static and dynamic applications
• Used for rod and piston
• Wide compound range
• Excellent chemical resistance
• Excellent resistance to heat (+260°C)
• Excellent resistance to cold (-200°C)
• Excellent resistance to ozone, ageing and weathering
• Excellent resistance to water and steam
• Wide range of dimensions
• Low friction
• Some compounds are approved for contact with foodstuffs
• Easy installation and removal

APPLICATION
Used in almost every industry but especially in non-moving machinery and in static sealing applications.
All types of hydraulic cylinders, injection moulding machines, mining equipment, marine hydraulics, loading platforms, cranes and heavy duty applications. BU3 back-up rings can be used in closed grooves.

INSTALLATION
PTFE back-Up rings can only be compressed or stretched to a very limited extent during the installation, to avoid deforming the back-up. Easily assembled into the housing by hand. The back-up ring is in non split form. If installation is difficult, the back-up ring can be cut carefully at a 30°- 45° angle and assembled afterwards. It is very important that the assembly tools must be of soft material and have no sharp edges.

NOTES
For applications where the pressure changes from side to side, a back-up ring should be mounted on both sides of the O-ring. For special applications PTFE back-up rings can be produced on request.

For further information about back-up rings, please call us.

*Teflon® is a registered trade mark of DuPont Performance Elastomers.