Back-Up Rings

Back up Rings

PTFE Polytetrafluoroethylene

Back-up Rings are manufactured from virgin PTFE as standard. In view of the unfavourable cold flow behavior of virgin PTFE, these Back-up Rings are only used for low to medium loads.
For higher load requirements, filled PTFE Materials (with glassfiber, bronze, carbon, etc.) have to be used. For sealing against high pressures, Back-up Rings made from specially
modified thermoplastic materials are available.

NBR - Nitrile Butadiene Rubber

The properties of nitrile rubber depend mainly on the ACN content, which ranges between 18% and 50%. In general they show good mechanical properties. NBR has an operating temperature range between -30 °C (-22 °F) and +100 °C
(212 °F), but can withstand up to +120 °C (+248 °F) for a short period of time. Suitably formulated NBR can be used down to -60 °C (-76 °F). NBR is mostly used with mineral based oils and greases.

FKM - Fluorocarbon Rubber

Depending on structure and fluorine content, FKM materials can differ with regards to their chemical resistance and cold-flexibility. FKM is known for its non-flammability, low gas permeability and excellent resistance to ozone, weathering and aging. Fluorocarbon rubber has an operating temperature range between -20 °C (-4 °F) and +200 °C (+392 °F), but can withstand up to +230 °C (+446 °F). Suitably formulated FKM can be used down to -35 °C (-31 °F). FKM is also often used with mineral based oils and greases at high temperatures.