Air-Assisted Airless Versus HVLP

      More discussion of the fine points distinguishing air-assisted airless spray-gun systems from high-volume low-pressure systems. April 30, 2006

Question
I don't get it. Does choosing the type of spray system have anything to do with how much and what type of production my shop is putting out? I wouldn't think of purchasing a AAA system if I sprayed a kitchen a month, as I wouldn't use an HVLP gun if I sprayed a kitchen a day… If I was going to choose an HVLP and I have a good compressor with clean dry air, wouldn’t I want a true HVLP gun rather than a LVLP or any other conversion type designed HVLP gun? What is a true HVLP gun?

Forum Responses
(Finishing Forum)
From contributor C:
I spray a kitchen a month and I invested in an AAA system. Well worth the money, I think.



From contributor R:
I spray one kitchen a week, and tossed out the AAA Binks because I didn't like it. I use a HVLP gun hooked up to a pressure pot, a Binks pot and a Binks gun. Not really sure what a "true HVLP" is, but I do like a gun to put out some pressure as I do spray a lot closer to the surface than most do. Got a huge compressor and drier dedicated just for finishing so if you can afford it, go big. For minor detail work I also have a few different guns but they are all HVLP, Sata, DeVilbiss, gravity fed guns. About the only difference with an AAA is the fact that you can apply the material in a less than bastardized condition.


From contributor S:
A true HVLP uses a turbine and is not just a HVLP gun and comp. You can also use an HVLP gun with a pressure pot and a comp. The difference between any of these and an air assisted airless is huge. The AAA puts out more material with very little overspray. It doesn't work your comp to death and you're not always having to fill a pot or cup or whatever. Although you do need to keep the lines clean and if you are using CV and forget it in there over the weekend, you get to buy a new one. But that pretty much goes for anything. Personally, I use a conversion cup gun for small jobs or spraying dye, a pressure pot with HVLP gun when someone is using my AAA, and a AAA for the big jobs. When it really comes down to it, the AAA is the best way to go for a professional job.


From contributor T:
Contributor S pretty much nailed it! HVLP stands for High Volume (of atomizing air) at a Low Pressure. Originally our industry used cup guns that were called conventional guns. They used a lot of air at a high pressure (20 to 60 psi).


From contributor W:
When it is all said and done, it's what you want to have for the work you have. If one kitchen a month does not justify the cost of AAA, then go to a pressure pot setup. Then you need to correlate the requirements in CFM's for the gun and the CFM output of your compressor. If the gun requirement is high and your compressor is low (not enough for the gun), then you will have delivery and application problems. Low CFMs are required from compressor for your AAAs. A lot of spray HVLP guns require a high output from the compressor. Some not as much as others. At least this has been my experience.


From contributor D:
I use all of them. I do not know about AAA in general except that the Kremlin Airmix will produce the finest off-the-gun finish I am capable of laying down. When I am only doing one refrigerator panel, I want to use the Kremlin Airmix. I really do not care about transfer efficiency. I care about one thing - the quality of my finish coat. The Airmix lays down a lot of material. The amount of overspray might be of interest to an EPA person, but not me. However, since overspray floats in the air and lands on my newly laid finish, then I do care a whole lot. It ruins what I just sprayed. And therefore overspray is an issue and a situation that reduces overspray is my concern. All that said, it spells one thing - "Airmix" for the topcoats.


From the original questioner:
Thanks for the responses. I'm interested in purchasing the AccuSpray 10 or 12 gun with a diaphragm pump using my shop compressor. These are supposed to be true HVLP guns? Of the units I've looked at, they seem to provide the best atomization, fan adjustability and highest material transfer. My finisher says that cleanup is a lot easier too. Nobody mentioned diaphragm pumps. Are they being used or are there problems I don't know about?


From contributor J:
Diaphragm pumps are used as an alternative to pressure pots. They clean up quicker and are really simple and need very little maintenance.


From contributor I:
How much cfm is required to run one?


From Paul Snyder, forum technical advisor:
"True" HVLP means there's 10 PSI or less at the air cap and the transfer efficiency is at least 65%. HVLP guns can be connected to a turbine or air compressor. HVLP guns that connect to a compressor are usually called "conversion HVLP." LVLP guns just use less air... that means you can use them with a smaller compressor. Diaphragm pumps are a good option. Not as fast as a AAA pump, but you have the ability to feather the spray.


From contributor V:
The diaphragm pump from Accuspray is their answer to AAA. You take the whole lid assembly, attach it to the top of your 5 gallons of finish, prime the system and spray away. They deliver slightly better transfer rates than the HV or LVLP's with a pot and are meant for production use. I use Accupsray's 12c gun (LVLP compressor driven) with their 2 1/2 gallon pressure pot. I have two set up and use them for clear and tinted topcoats and stains. They work very nice and don't give very much overspray. My guess is they give me a TE of 75%. Accuspray typically has higher TE rates on their guns than other HV or LVLP ones.


From contributor G:
How can a diaphragm pump deliver better finish than a pot? Same gun... no? And saying Accuspray has TE of over 65% on their HVLP is false advertising.


The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor I:
A true HVLP means that your gun is powered by turbine (6-8psi and 100cfm). A conversion gun as its name suggests converts high pressure air from compressor to lower and higher volume (you need one mighty compressor to supply needed amount of air). As for airless pumps - they do not use air at all the paint atomizes because it ejected at very high pressure (200bar). Third system combines two airless with air either from compressor or turbine, the air is used to "envelope" the spray fan to further reduce overspray.



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