Sprayer Adjustment

[jteneyck]

Edit to correct myself:  I also ran latex through some of my HVLP spray guns to spray some wall cabinets for my shop, part of the reason I experimented with drilling out the HF nozzles.  I even went so far as to buy a Vaper spray gun with a 2.3mm tip from my local Northern Tools but even that struggled without thinning the paint a lot.   In short, I don't recommend using HVLP for latex.  I understand the airless do much better with latex, although overspray can be an issue.

I spray waterborne paint all the time with my HVLP gun without thinning it.  The key is you need a pressure pot or pressurized cup.  I have a Qualspray  AM-6008 HVLP gun with the 3M PPS pressurized cup system.  It can spray everything from water based dyes to BM Advance and SW ProClassic w/o thinning.  I only have the 1.0, 1.3, and 1.5 mm N/N's, too, but you can get them up to at least 2.0 mm, so you could spray even higher viscosity stuff through that. 

You get all the benefits of HVLP when spraying high viscosity products IF you pair it with a pressurized fluid system.  I think most all the turbine guns have a pressure assisted cup as part of their design.  Conversion guns can be converted to pressure assist by hooking them up to a pressure pot or adding a PPS System.  

John

[Snipe Hunter]

Actually, the way I understand it, and as I said, I am no pro painter just a curious amateur, is that an HVLP spray gun only puts out 10 psi at the tip as you say, but that does not mean they don't use more pressure at the inlet.  Many of these spray guns that run off of compressed air take a max. of 30 psi at the inlet and internally reduce the pressure down to 10 psi.  The regulator attached to the end only ensures the spray gun is getting the 30 psi or so at the inlet of the spray gun.  My understanding is that there is much more to it than a "regular old fashioned spray gun with a regulator".  

Not trying to contradict you, just explaining it the way I understand it.  If I am mistaken, please correct me.

To complicate matters, there are also LVMP spray guns that run on lower volume, slightly higher pressure and are considered "compliant" in that they meet HVLP "pollution" criteria but can be run with smaller compressors, they are supposed to run at an intermediate pressure between HVLP and conventional spray guns, its these spray guns I think of when I hear "conversion spray guns".  And then there are LVLP spray guns which I have not seen too much information on other than they are supposed to be good for people with portable air compressors but only good for "smaller jobs", but that is assessment from folks spraying autos.  

Thanks,
Paul

You are right in your synopses. Where you may be wrong is if you actually tested the PSI at the tip. On the better guns ($300 range), you will indeed find 10 psi or less at the tip. But not on the cheaper ones.

I use a turbine gun professionally. I did own a painting franchise and in training we tested all sorts of guns..... including the purple HF gun. We also tested another popular gun that is branded by many different suppliers. Only 2 of the approximately 10 guns tested put out 10 psi or less. One was a SATA and the other was a Binks. Both those guns are in the 300 dollar range. None of the cheap guns were even close to 10psi unless the regulator was turned to 10 psi.

All of the turbine guns put out the same psi as the turbine itself or a hair less. The best was a three stage turbine and it was still less than 9psi. I still usa an old 2 stage turpine and I get closer to 7psi. 7psi out of a cheap conversion gun only spits. 

The way the good ones work is that the air as choked down in the gun through a small orifice. Then the air passage gets bigger again after that orifice and there several holes in the air-cap which all drop the pressure and still give you decent volume. So less air is moving through the business end of the gun.

I chose to go with the urbine guns (AccuSpray) because EPA cops now they can't put out more than the turbing and no turbine puts out more than 10psi... And, they aren't as finicky when they go without cleaning. The type of work I do dictates that I don't have time to clean my guns. I rinse them after use but they never really get a good cleaning. I couldn't do that with a conversion gun. I have a primer gun that I keep primer in and it hasn't been cleaned in 5 years. It's a daily user. My paing guns don't often get a geed cleaning. Maybe once every couple years? I squirt lacquer thinner through them between colors. I do keep the needle, tip and air-cap clean on my clear-coat gun. I keep them in lacquer thinner between uses and wipe them down with a paper towel and blow them dry prior to the next use. The needle stays in the gun, I just wipe off the tip.