Wagner HVLP Conversion Gun

[Jerry Bittner]

Just took delivery of the above and began some experimenting to get an idea of the ideal compressor and regulator pressures to obtain adequate spray. According to Gleem's tech support, they say the ideal pressure at the gun regulator should be 9 to 10 psi with a full flow. To achieve this I found for my Craftsman compressor, I need to maintain a pressure regulation of 80 psi. I don't know if this higher pressure translates to more overspray from the gun or not but it is what is needed on my compressure to maintain 9 to 10 at the gun.
I should add that according to Gleem you start your experiment with the compressor set at 40 psi and the gun regulator at 20 psi. Further, if your gun will not maintain the 9-10 psi, you adjust the compressor regulator (higher) in 10 psi increments until you get the desired maintenance pressure.

So given the fact that the unit will produce some overspray, has anyone come up with a plan for the small workshop to build a portable (preferably knock down) spray booth?

Thanks in advance for any advice.

[Joe Scarfo]

A good friend of mine has that gun and speaks farily well of it...

His has a pressure regulator at the base of the handle, there is where you can set the pressure the gun uses to shoot the coatings. The regulator at the compressor he keeps in the 80 PSI range.

He's ok w/ shooting stains and clear coats and refuses to spray paint again. WE use my porter cable gravity feed HVLP for that. Cleaning paint out of the plumbing and the cup is just to much work.

Good Luck
Joe in Tampa

[Ken Garlock]

Hi Jerry. As I recall the gun has a pressure regulator at the input to the gun. Given that the regulator is doing its job, you should/will not see a difference in spray pattern. Change to output pressure of the gun, and then you will effect the results.

The question is really how many cubic feet per minute at 9 lbs are required? If you have that value, then it is easy to arrive at a pressure for your compressor. Using the formula P1V1 = P2V2 you can calculate your compressor pressure setting and the volume of air required. It is possible that you will find that your compressor can not produce sufficent air for the gun.

Example: gun requires 10 CFM at 9 psi. Your compressor can deliver up to 8 CFM at 40 psi. P1V1 is 10*9=90. Working at 40 psi your compressor needs to supply: P2V2 = ? -> 40V2 = 90, V2 = 2.25 CFM Since the compressor in this example can deliver 8 CFM, then you are OK to run at 40 psi - the compressor can "keep up" with the needs of the gun

My approach would be to:
1. Write down the specs on your compressor at various pressures and volumes.

2. Compute the product of recommended gun psi and air volume at that psi.

3. Divide that product into various compressor pressure to see if the result is within the CFM capacity of the compressor. If it is, then play with different compressor pressure values until you find one that is hopefully in the mid range of the compressor capacity, both pressure and volume.

Thus, if you know three of the four values of pressure and volume you can compute the fourth one. If all four values then fall within the capacity of the gun and comprressor you are good to go.

[Jerry Bittner]

Thanks all for the informaton. With some experimenting as recommended by the guys from GLeem, I found that the magic number for the Craftsmand 5.5 hp 25 gal compressor is 80 psi at the regulator to maintain 9 psi at the gun.

Tomorrow I hope to test it with some varnish and see how much I have to thin it to get the proper spray.