How should I select which ferrule material is best for my application?

There are 3 main points to consider:

• Temperature rating:
  • Graphite ferrules – 450 ⁰C
  • 85/15 vespel/graphite – 350 ⁰C
  • 60/40 vespel/graphite – 400 ⁰C
• Permability to oxygen. Graphite ferrules are easy to work with, but are permeable to oxygen, vespel/graphite are harder and therefore more difficult to tighten but are not porous to oxygen.
• Potential for system contamination. Graphite ferrules can contaminate the GC, while vespel/graphite do not pose this issue.

Graphite ferrules work best for high temperature applications, with vespel/graphite making a good option for oxygen sensitive detections such as MS. Siltite ferrules can be used for high temperature MS applications.