Common O-Ring materials that are SUITABLE for dynamic and static seal in the environment containing Freon 31 include

• Butyl: Butyl (IIR) is a synthetic rubber, a copolymer of isobutylene and isoprene.
• Ethylene-Propylene: Ethylene-propylene (EP) is a copolymer of ethylene and propylene.
• Neoprene: Neoprene is a homopolymer of chlorobutadiene (CR).
• Virgin Teflon: Because Teflon is a hard plastic rather than a stretchy elastomer, it is uncommon to see an o-ring that is made entirely of Teflon.

The O-Ring materials below are USUALLY SUITABLE for static seal in the environment containing Freon 31.

• Chemraz: Chemraz combines the resilience and sealing force of an elastomer with chemical resistance approaching that of PTFE.
• Hypalon: Hypalon is the traenme of a clasof Chlorosulfonated Polyethylene (CSM).
• Natural Rubber: Natural rubber is a product coagulated from the latex of the rubber tree, hevea brasiliensis.
• Styrene Butadiene: Styrene-Butadiene rubber (SBR) has properties similar to those of natural rubber.

The following O-Ring materials are SOMETIMES OK for static seal but not for dynamic seal in the environment containing Freon 31.

• Polysulfide: Polysulfide was one of the first commercial synthetic elastomers.

O-Ring materials that are NOT SUITABLE for using in the environment containing Freon 31 include

• Buna-N (Nitrile): Buna-N, also known as Nitrile rubber, is a synthetic rubber copolymer of acrylonitrile (ACN) and butadiene.
• Fluorocarbon: Fluorocarbon elastomer (FKM) material is also known by its tradename VITON or Fluorel.