Your question is unclear. 500 microns of what? Water? Mercury?
In any event, this information would probably be found on a material property sheet from the manufacturer.
Millitorrs are generally called "microns". It is assumed among refrigeration engineers that during vacuumation processes the oils in systems worked upon, themselves, do not boil - no matter how high vacuum would be achieved. I am in doubt.
PS: in the sciences we call a millitorr a millitorr ... your use of "microns" refers to "microns of Hg". I'm sure it is useful in your engineering jargon as a short way of saying what you mean, but it is certainly not a common expression.
I have already read this thread, thank you. (but it did not answer my question)