Why would someone choose a metal seal system over an elastomer seal system and vice versa?
The main reason for choosing a metal seal system is in the level of vacuum that can be achieved. Elastomer seals allow air and other gases to permeate through them faster than through copper, and therefore are restricted to high vacuum applications. Metal seals have lower rates of permeability and can be baked to higher temperatures than elastomers, and are therefore used for ultrahigh vacuum applications. If achieving ultrahigh vacuum is not critical to a process, an elastomer seal system provides high vacuum capability at the least cost. Disadvantages of a metal seal system are single use of gaskets, more time required for assembly and disassembly, and a greater expense. Disadvantages of an elastomer seal system are limitations in vacuum level and restrictions in baking temperatures.
