Chicago Rawhide Backing Rings

Back-up rings are intended to be used together with O-rings when the fitting clearance between the surfaces that the O-ring should seal is large enough to allow the O-ring to extrude at certain working pressures. In installations with normal and standardized dimensions and tolerances the O-ring normally must be completed with back-up ring(s) if the working pressure exceeds 10 MPa (1 450 psi), depending on the temperature.

In applications where the O-ring is exposed to pressure from one side only, the back-up ring is installed at the zero pressure side. For an O-ring exposed to pressure from both sides a back-up ring is assembled on either side.

Our back-up rings are kept in stock with a basic design and are produced of polyurethane 95° Shore A or of a polyester elastomer, 95° Shore A. This enables the use of back-up rings in most applications with normal pressure media and temperatures.

In applications with high temperatures or aggressive media back-up rings of a PTFE material are suitable, either unfilled or with an appropriate filler. We keep a large number of sizes of unfilled back-up rings of PTFE in stock. These are machine finished and can therefore be delivered within short notice.

Chicago Rawhide O-Rings

Chicago Rawhide normally stock standard O-rings of nitrile rubber (NBR) 70° IRH. When necessary, the alternative hardness 90° can be delivered at request. It is, however, better to choose 70° IRH and combine the O-ring with a back-up ring.

For applications with temperatures over +100 °C (+212 °F) fluoro rubber (FKM) or silicone rubber (Q) can be appropriate, depending on the medium.

PTFE encapsulated O-rings, type ECOR

Type ECOR is an O-ring consisting of a seamless and uniform PTFE encapsulation which completely encloses the core material of either silicone or fluoro rubber to protect it from media and air.

The function is the same as for a normal O-ring that is compressed in the groove and is working statically. Type ECOR is not appropriate for continuously dynamic applications due to its thin and soft case.

Advantages of ECOR

• Chemically resistant to aggressive media thanks to the PTFE encapsulation
• Wide temperature range, –60 to +205 °C (–80 to +400 °F), material type PFA +260 °C (+500 °F)
• Anti-adhesive, no stick-slip effects
• Sterilisable, FDA approved
• Low steam permeability and low water absorption
• Low compression set solution.