release valve. Bleeder guns blow air through the tip constantly, even when the trigger is released. Nonblecder guns (which require the in-line valve) shut oH both air and fluid at the gun when the trigger is released. I prefer non-bleeder guns, since constant air coming through a gun blows dust around the spray area.
Most turbines are portable and plug into a standard 115-volt electrical outlet, making them ideal for spraying on-site. Depending on quality and features, turbines can cost anywhere from several hundred dollars to more than $1,000.
In my shop, 1 use an Accuspray 10, which is lightweight, comfortable, and delivers good atomization. This non-bleeder gun—like some other turbine guns—accepts a conversion unit which allows it to be powered off a compressor instead of a turbine. (See left photo, page 66.) Altogether, the gun, convcr-sion unit, two caps, and three tip assemblies cost about $495.
An HVLP conversion gun converts compressed air into low-pressure air by means of a conversion "unit" that is mounted either in the gun, on the gun, or on a wall. The first two types of conversion units use an easy-to-manage 3/8-in.-i.d. air hose. Wall-mounted units use a 1 -in. hose.
Unlike turbine guns, conversion guns allow you to adjust the air pressure at the gun's tip by changing the line pressure going into the gun. A line pressure of 80 psi converts to 10 psi at the gun tip—enough to atomize even thick coatings. That 80-psi line pressure, however, must be backed up by 12 to 20 cfm of air, which requires at least a 5-HP compressor.
I also use a conversion gun—a DeVilbiss JGHV-5284-FX. This is the most powerful HVLP gun I've used. It provides great atomization and delivers lots of material fast. It requires about 18 cfm of air (at 80 psi) and sells for about $400. but it's worth every penny.
Assuming you've decided to take the plunge into HVLP, your choice of gun depends on your Finishing needs and existing equipment. If you don't own a large compressor and if you sometimes spray on-site, I suggest getting a turbine gun and turbine. If you own a large compressor, a conversion gun will provide greater power and finishing flexibility and save you the cost of a turbine.
See AW #28 for a review of HVLP turbines and guns. ▲
Join Michael Dresdner live on America Online Sunday nights from 9:30 pm to 10:30 pm eastern time for answers to your finishing questions. From Amikican Woodwokkik Magazine Online, click the "Shop Talk" icon to enter the finishing chat room.
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