What's the air adjusting valve for?

[timinator]

I just bought a new Devilbiss HVLP gun. I understand what the fan control and fluid needle control are, but at the bottom of the gun where the hose connects, there's a "air adjusting valve". What's this for and how do I set it?

[Len]

HVLP guns are very sensitive to the amount of inlet air pressure and the pressure needs to be set at the gun in order for it to spray properly. Different guns demand different inlet pressure, the DeVilbiss GTI needs 30 PSI with the trigger pulled and air passing throught the gun. You should hook up your air hose and adjust the pressure from your wall regulator to read between 60 and 80 PSI then pull the trigger on the gun and adjust the inlet pressure gauge to read about 30 PSI.


http://autobodystore.net/Merchant2/graphics/00000001/devhav501.jpg

[Dennis N. Schmidt]

These are completely useless. Either use a diaphram regulator like a Sharpe 1410 or look at the gauge on the wall as Len suggests. I throw these cheater valves out immediately upon receipt.

[Roch_Greg]

On my DeVilbiss SRi-W there is the same valve, but they are thinking that your going to use their own tool that plugs into the tip to measure the pressure and set the gun using that valve.

I use what Len posted and leave the valve all the way open.