a) What pressure units do you know?
Pascal (Pa, SI unit), bar (bar, SI conform), Torr (Torr) and pounds per square inch (psi) are frequently employed.
b) Do you know their conversion factors?
Only the Pascal is an SI unit, but fortunately, the mbar is just a 100 times larger. The other non-SI units have disadvantageous conversion factors.
Hint: Navigate to “Downloads” to get a handy pressure units conversion table.
c) In what pressure range are mass spectrometers normally operated?
Mass spectrometers are usually operated in the high vacuum regime to ensure mean free paths significantly longer than the mass analyzer’s dimensions.