"BFC" baffles

The baffles of the BFC series are positioned above the diffusion pump and effectively shield the vacuum chamber from the physically induced propellant backstreaming. This enables generation of a practically oil vapor-free vacuum. The housings are made of stainless steel. The built-in components such as baffle plate, chevrons, and cooling coils are made of copper. The specially coated inner walls of the housing serve as propellant barrier and further reduce oil backstreaming.

The internal cooling circuit can be cooled either with liquid nitrogen, Polycold, a refrigeration unit, or water. The external cooling circuit is always cooled with water. The choice of the cooling medium has a significant impact on oil backstreaming. Colder cooling media reduce backstreaming more effectively than warmer ones.

When choosing liquid nitrogen or Polycold, water vapor is additionally pumped, which condenses on the chevrons. The pumping capacity for water vapor is then equal to that of a cryopump with the same diameter.