Different nozzles, different media types and different pressure. All depends on what I am doing.
Stripping rust/paint use 90 lbs. PSI, crushed glass, #7-8 ceramic nozzle.
Finish/smooth/semi--polished finish, #10 glass bead, 40-50 lbs. PSI, #6 nozzle.
There re many others. If you go online to...