Our annulus system uses 55 l/sec ion pumps to maintain the vacuum between the oring seals. MEDM screens show ion pump current which is also a measure of pressure at the ion pump inlet flange.  See the attached file for the pump curves and the current to pressure conversion. We have 46 of these pumps throughout the system.

1 mbar ~ 0.75 torr

1 bar = 760 torr = 1 atm