Air Pressure Settings for HVLP guns

Set the pressure regulator with the trigger pulled, is the rule. December 15, 2005

I've only used turbine-driven HVLP units since the early 90's. I have never sprayed with compressed air. I just recently switched over to using an HVLP gun on my compressor and (duh) I love it.

The gun requires a maximum air pressure of 45psi, which is easily managed with a regulator. But do you set the 45psi with the trigger on or the trigger off? If I set my regulator to 45psi and pull the trigger on the gun, then the pressure drops to something like 25 psi (just a guess). Does the 45psi requirement take this into account or do I need to set the regulator with the trigger pulled? I have it set to 45psi right now with the gun off and it works fine.

Forum Responses
(Finishing Forum)
Glad you can appreciate the difference. If 45# with gun off works fine, then you're fine! I switch between high-pressure guns and conversion HVLP all the time. I leave my regulator at 45# with a 25' 3/8" air hose.

By convention, this value is always specified with the trigger fully pulled. With low solids wood coatings, 25 PSI will normally atomize these just fine. With high solids acrylic urethanes used in automotive refinishing, this setting would result in unbelievable orange peel. But to specifically answer your question, the value at which the gun is supposed to be set is always with the trigger fully depressed.

From the original questioner:
I agree with the sentiment that if it ain't broke, don't fix it, but I also want to get the most out of every tool. Yesterday, I sprayed almost 100' of cabinetry with sanding sealer and I had to have the air dialed almost all the way open on the gun to get the atomization I wanted. Now that my question has been definitively answered, I can see that turning up the regulator would give me a little more flexibility in the gun settings. Thanks to both of you - it really helped.