mole%. Local regulations and company policy may dictate different maximum
mole% oxygen that is permissible. If no policy exists, then if the analysis shows
that the oxygen content is at or below 0.3 mole%, the unit has been air-freed. If
the oxygen content is still greater than 0.3 mole%, continue to pull a vacuum and
check for leaks. After the final vacuum is pulled the reactors should be
pressured up to 1.0 kg/cm2g (15 psig) in preparation for filling. The higher
reactor pressure is because the filling will be completed with benzene at 90 deg
C.