HVLP + compressor vs. HVLP + turbine
I have a small shop and find the turbine system great. One problem, however, is that the warm air coming out of the gun will dry solvent-based finishes before they hit the surface, producing orange peel. It doesn't seem to happen with water-based. For solvent-based, retarder is essential and 40 feet of hose is recommended.
As for air-driven HVLP, you better have a HUGE compressor.
I've used both for many years -- I now use a 4-stage turbine for on-site work and, in the shop, a 7-1/2 HP compressor with 80 gallon tank and 3-in-1 refrigerator-dryer. This keeps the moisture under control in the airlines.
Turbine sprayers will run for years, problem-free, if you keep the intake filter clean.
Compressor sprayers will heat up if used on large jobs and cause premature failure. Otherwise both sprayers work well if used under the right conditions for each sprayer.
A huge compressor is needed for an air-driven gun? Not necessarily: there are conversion guns that will run off of compressors as small as the 1.5 hp size.
I know of a couple of great conversion guns that need only 4 to 6 cfm at 20 to 30 psi. These are very efficient, portable guns.
I also use a turbine system. The 40-foot hose is not possible for me because I only have a three-stage turbine.
There are benefits and liabilities to each system. The conversion guns that I have alluded to seem to offer more versatility for a finisher because a compressor.
The JGHV DeVilbiss HVLP gun can run off of a $400 Home Depot, Campbell-Hausfeld extra heavy duty compressor with a 60-gal reserve tank, and will run with the tank empty and running wide open. I wouldn't do it for eight straight hours, but it works for normal spray cycles.
The biggest drawback of the turbine is the fluid pressure in the cup. It's minimal, and spraying large pieces of material is difficult since the far egde of the material is drying and the near edge is still being sprayed, causing a rough finish due to overspray. It helps if you can increase the fluid pressure and get more juice on the material faster for a good, uniform, wet coat.
From the original questioner:
Thanks all for the input.
Today I rented an Accuspray 240 HVLP turbine system, and sprayed an oil-based black enamel through it. It worked great, but if I'm going to spend that much money, I think I would lean toward a compressor running an HVLP gun, mainly for the versatility of having a compressor, and because I don't need portability.
If you purchase a turbine unit, be prepared to replace the motor if you spray continuously. They heat up considerably and wear the bearings out.
You can place a fan next to the turbine to circulate the air. I am on my second motor in the past six months. Luckily, Grainger has good customer service. The 3-stage motors retail for $127. I am getting good at replacing the motors; it takes about 1.5 hrs.
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I don't like the large O.D. turbine hose or the heat given off. Binks has a LVLP line of air caps for their HVLP guns that start off with the 90P air cap that is designed to work with a 1.5 HP compressor.
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