Vacuum specification

Anybody can venture an opinion !! Does anyone have a definitive spec for the depth of vacuum in a close control unit, My thoughts are 1-2 mbar (750-1500 microns) the local agent for the machine is asking for 400 microns and can't give a valid reason why it has to be so low. Can you help me ?

Because 400 is drier than 750 ??

Around 1000 micron for AC stuff but you should go lower for refrigeration type levels.

500 microns is a good pull the reason being is if you got a tight system youll get that if it leaks you wont.