Precision Glass Works

O-Ring

The O-ring is the most universally recognised seal design and easy to mount. It is the most critical component in the Pressure tube, creating the tight seal between the PTFE cap and glass. O-rings of different compositions are available depending up on the chemical resistance and aIso the environmental conditions including temperature range and pressure. Our suggestion will be to use FFKM O-ring for best performance. Please refer to our O-ring compatibility table for more information.

  • For more details on different sizes, avialbility as well as cost, please contact us
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FKM (Viton® / Alwin Höfert KG)

FKM is the ASTM designation for a class of fluorinated, carbon-based synthetic rubber, commonly known as fluoroelastomers. FKM has impressive heat resistance, allowing FKM seals to withstand temperatures greater than 200°C. FKM also exhibits extraordinary levels of resistance to high pressures, chemicals, and other fluids (including several fuels). However, FKM has its limitations and please refer our O-ring compatibility table for finding whether FKM suits your requirement

FFKM (Kalrez®/Chemraz®)

FFKMs (by ASTM D1418 standard) (equivalent to FFPMs by ISO/DIN 1629 standard) are perfluoroelastomeric compounds containing an even higher amount of fluorine than FKM fluoroelastomers. They have improved resistance to high temperatures and chemicals and even withstand environments where Oxygen-Plasma is present for many hours. Certain grades have a maximum continuous service temperature of 327 °C (621 °F). FFKM or Perfluoroelastomers are a highly durable material that provides a long service life in tough environments, can withstand attack from more than 1,800 chemicals and boasts resistance to extreme temperatures.

  • Temperature resistance up to +327°C
  • Extraordinary chemical resistance
  • Retains elasticity similar to FKM
  • Reliable and long-term service
  • Boasting enhanced physical performance properties including a very low compression and improved seal force retention

Chemical Compatibility Guide

Please select two Materials below to test against each other:

Chemical Compatibility


*The information in this chart should be used ONLY as a guide in selecting a material