Material
Butyl (IIR) O-Ring Material Guide
Butyl properties and low gas permeability for vacuum sealing.
Polymer
Butyl (IIR)
Temperature range
−45 °C … +125 °C
Hardness
50–80 Shore A
Overview
Butyl's defining property is extremely low gas permeability, which makes it the preferred elastomer for vacuum systems and gas-tight sealing. It also resists phosphate-ester hydraulic fluids, glycol brake fluid and many acids and bases, but it swells badly in petroleum products.
Strengths
- • Lowest gas permeability of the common elastomers
- • Excellent for vacuum and gas-tight sealing
- • Resists phosphate-ester fluids and glycol brake fluid
- • Good resistance to acids, bases and ozone
Limitations
- • Swells badly in mineral oils and fuels
- • Slow elastic recovery and poor abrasion resistance
- • Limited high-temperature capability
- • Not suitable for petroleum-based hydraulics
Compatible media
Vacuum & gasesPhosphate-ester hydraulic fluidsGlycol brake fluidAcids, bases & ozone
Media to avoid
Mineral oils & greasesFuels & hydrocarbonsPetroleum solventsAbrasive dynamic duty
Typical applications
Vacuum systems and chambersGas-tight and low-permeation sealsPharmaceutical closures and stoppersPhosphate-ester hydraulic systems
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