Commonly used flange designs have a soft gasket squeezed between harder flange surfaces to form a leak-free seal. The various gasket materials are rubbers, elastomers (springy polymers), soft polymers covering a springy metal (e.g., PTFE covered stainless steel), and soft metal (copper or aluminum). Each flange design has merits.

When planning a new vacuum chamber, the designer should compare all the flange designs available and choose that which:

1.Matches the vacuum conditions required
2.Matches the temperature conditions required
3.Is unaffected by the process's starting materials or products
4.Matches OEM fittings and components added to the system
5.Is easiest to use in that particular system
6.Has the lowest total costs