Backup Rings are available in the following standard styles and materials:
- Solid Split (PTFE) – used to eliminate extrusion of the O-ring at pressures above 100 bar
- Spiral (PTFE) Used in cases where fluctuations in temperature occur. Even if there is any post-shrinkage of the backup ring, there will be at least one turn of the spiral along the surface of the O-ring to prevent any extrusion. Also can be adapted for non-standard diameters, as the ring can be shortened to suit.
- Parbak (NBR)
The advantages of using Parbak are:
- They are moulded in a one-piece contoured design which improves performance by enabling the O-ring to keep its shape under high pressure.
- Can be stretched easily into place.
- Parbaks do not cause the localised wear on o-rings, which is the characteristic of other types of backup ring.