Setting compressor PSI

See Don Wheelers airbrush page on the subject 

https://sites.google.com/site/donsairbrushtips/air-hose-loss

He found 20 to 35 percent hose airloss

He also notes that you should tune for your results, not absolute pressure 

Personally, I set my pressure with the trigger depressed - and adjust from there    

I also have  30 PSI final air gauge    Pressure gauges can be off as much as 10% full scale    Worry about that next  

Thank you, Ed.  I had not even considered the line diameter and length factors or, thanks to you, pressure gauge accuracy.  LOL.  I'm going to employ your protocol. Thanks again.  

So many things about psi makes me want to scream It Depends lol ! So I can say for sure, use what makes your paint flow right. To me the pressure setting is just ball park initially so you're not getting tank pressure. Now with my DA which has a mac valve I just set the gauge to 25-30 psi and use the mac valve on the AB to dial in a nice lay down of paint. In a nut shell, you don't want spatter which indicates too thick a mix of paint or too low a pressure for the distance you're spraying at. And you don't want center blow out, indicating too thin a mix or too close for the mix or too high a pressure for the mix at that distance. At the same time you can formulate over time a repeatable combo for a given paint.

Static pressure in your line means 0, it's useless information and unprofitable to your end product. When I get used to a brush and thinned paint combo I can get along pretty well adjusting my pressure on the drop in pressure with air flowing if using a brush without the mac valve. But the ultimate determining factor is how the paint lays down, the regulator might need a crack more or less air depending on how the paint looks after a pass or two.

Many thanks.  I am glad to learn that static pressure not a useful measurement.  Thanks also for the notes regrding various air brushing issues, their causes and remedies.  Very helpful.  

I would also expect the pressure drop to depend on flow rate, especially on a DA action brush.  I find in my tankless Iwata brush the drop is primarily from flow.  I get a 5 psi drop from flow with my SA brush.  That is the pressure gauge on the compressor, so it must be the drop across the regulator.  I am using the badger hose so I have no idea what the pressure is at the brush itself, but it works fine with the pressures I set (with flow).

Thank you, Don  It's beginning to come together for me and I am really enjoying my experience with DA brushes.  But my thirty plus year old Paasche H still lays down a very nice spray.  

Dale

Just depends on cfm capacity of the compressor and the airbrush. Like the Paasche H is unrestricted and the #5 tip for instance is high flow, most tankless comps won't keep up with that. So in other words you get the drop and go to adjust the pressure up because it fell through the floor and you can't get it high enough to flow right with that nozzle and the paint spits,then people say the airbrush sucks when they just don't have enouogh cfm to feed it with that nozzle.. The #3 on the same brush probably will flow but the capacity of the comp is nearly maxed. A Badger 200 with .25 is a sweet heart on air imo, it's possibly my favorite combo anyway. None of that matters to me really because I rarely use the #5 on the H but also my comp is 8 gal with capacity to shoot my LVLP spray guns, its not going to starve any airbrush. And then there are some tankless comps that are fairly high flow too.

Some of the Iwata brushes are restricted on flow as are some Iwata knock offs as well, you could crank the pressure to 35psi but it's only gonna flow what the restriction allows ( I think it's either 20 or 25 psi). A Paasche H set to 50 will flow 50 if the comp and lines will give it that much and that #5 with enamel like 35 psi..

We can talk about air flow and paint flow all day though. Bottom line is to come to some settings that work for you.

Deaf Smith

Thank you, Ed.  I had not even considered the line diameter and length factors or, thanks to you, pressure gauge accuracy.  LOL.  I'm going to employ your protocol. Thanks again.