Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Unless you are using a dedicated compressor you definitely want a separate regulator on your bench, I was playing around with a vintage engine, then later did some home repairs so jacked up the PSI to 90 for the air nailer.
Couple days later went back to the vintage engine forgot to reset the regulator and blasted 90 PSI into the old thin boiler, it did not fair well.

This is the system I use, gauge is from a tire pressure gauge I picked up at an auto supply store for a very reasonable price.
http://steammods.com/runonair.html