A ring of oxygen-free high-conductivity copper used as the sealing element in CF flanges. Each gasket is used once, because the knife edges leave grooves that will not reseal reliably. Silver-plated versions resist oxidation through repeated bakes, and fully annealed soft copper rings are used on viewports and other fragile parts that cannot take full bolt torque.
Always a new copper gasket, I don't care if it looks fine, the last reused one cost us two days.
Also heard as
- copper
- CF gasket
- OFHC gasket
Related terms
CF flange
All-metal flange that seals by biting knife edges into a soft copper gasket, the standard joint for UHV.
Knife edge
Sharp circular ridge machined into a CF flange face that cuts into the copper gasket to make the seal.
Bake-out
Heating a vacuum system while pumping to drive off water and other adsorbed gas and lower the base pressure.