HVLP, 10 psi at the cap, how to measure?

[Reamer]

Hi all
With the Devilbliss Finish line series, They say have 10 psi at the air cap. Is that 30 psi into the Gun? 40?
Also they show all the neet bad patterns in the directions, What does a good pattern look like? A football shape?
What Ideal tip for Epoxie Primer?
PPG BC?
Omni Clear?

Ron

[Phil V]

Which Finishline gun do you have ? HVLP or non HVLP? Finishline I, II or III ?What is the full model number of your gun ?

[Reamer]

DeVilbiss Model 611103 (FLG-635) HVLP Gravity Feed

[Len]

You should squeeze the trigger and adjust the inlet regulator to 23/25 PSI with air blowing through the gun. I'd be using the 1.4 fluid tip for just about everything but for heavier materials you could use the 1.6 and they make larger tips like the 2.2 for really thick stuff.


http://www.autobodystore.com/Dev_FLG_combo.jpg

[Reamer]

I have the one on the left.
What does a "good" pattern look like?
I didn't know I could use a 1.4 for Epoxie prime, and BC and clear.
Ron

[Phil V]

reamer, your spray fan should be shaped like a cigar. What I do with just about every gun is adjust the fan wide open then turn the adjusting knob until the fan starts to narrow a little. I normally leave it right there. If the fan is too wide then you'll get a lot of dry edges from the overspray. If the fan is too narrow then you'll get tiger stripes in the metallic of the basecoat and very possibly runs in the clearcoat. Adjust the fluid control knob just about wide open and leave it there. Thats how most of the pro painters adjust their spray guns. Keep in mind that an HVLP gun is held closer to the surface that you're painting and so the fan works a little better when its a little wider than how a conventional high pressure gun would be adjusted to. You normally have to move a little slower with an HVLP gun compared to the conventional high pressure guns. Most HVLP guns are "slower" than conventional high pressure guns.

[Roch_Greg]

You had it right in the beginning, sort of like a football. The widest and wettest is towards the center then as you move toward each end you should see less material and the pattern should start to taper off.

[Phil V]

It should also be pointed out that the 10 psi at the air cap is pretty much generic to all hvlp guns. That 10 psi is a MAXIMUM air pressure recommended at the air cap. Look at it as a redline of a tachometer connected to a race engine. You don't have to run that engine at the redline rpm all the time you drive it. The same with the 10 psi max for HVLP air caps. That rating does not mean that the gun won't spray correctly if the psi rating is above or below that 10 psi. Most HVLP guns will actually do a better job to atomizing urethane single stage and clearcoats if you exceed the 10 psi rating. At that 10 psi max means is that the federal gov't has come up with a set of guidelines to where those HVLP guns spray their best transfer efficiency while atomizing the paints correctly. If you go past the 10 psi max pressure rating it just means the gun is not spraying within the gov't guidelines of optimum transfer efficiency. If you spray the pressure each particular gun is recommended to spray at by the people who manufactured that spray gun then you will be approaching the 20 psi max air cap pressure.

[Len]

If you spray the pressure each particular gun is recommended to spray at by the people who manufactured that spray gun then you will be approaching the 20 psi max air cap pressure.

Phil
Please explain this, I don't understand. Don't you mean 10 PSI?

[Phil V]

Len, you are definately correct, that was a typo. It should have read 10 psi not 20.

[INXS2]

DeVilbiss makes different air cap test kits for the SRi (SRI-5033-215 kit) and the Finishline III (FLG-463 kit), is there any standard type of air cap test kit that'll fit both (or all HVLP) guns?

[Phil V]

There is not need for an individual to pressure test for 10 pso at the air cap of an HVLP gun. The manufacturer has already done extensive testing with each of those guns and they supply the customer with the recommended inlet air pressure setting for that gun. If you use the gun at the manufacturers recommended inlet air pressure then you're in the ball park of what pressure to run the gun at.