Hello,
Generally over on knots so I appreciate any responce.
I am having my house painted, and I asked the contractor if he was gonna use a HVLP sprayer. He said they use an airless sprayer. I am famillier with HVLP for woodworking, but what is a airless sprayer?
thanks in advance
joe p
Replies
Hey joepez,
It's a paint pump, like hydraulics. High pressure, something like 3500 psi .
DAVE
An airless pump gets its name from not needing compressed air to deliver the material. I think the "hydraulic" mention is apt.
Essentially, there's a snout or intake that goes into the bucket of finish, at the operator end there's a gun with an interchangeable tip, and between the two is a pumping motor with a fluid line. It's pretty straightforward. If you recall high school physics, you probably heard the term Venturi Principle. Essentially, a tube with fluid and a given pressure, if necked down, the fluid going through the opening increases in velocity.
The pump exerts some given amount of pressure on the fluid, and when it reaches the tip, the opening is small enough that the resultant velocity is sufficient to atomise the fluid for spraying. The pressure is adjustable, either via a knob with a simple + - on either side, or on higher end pumps a digital readout which gives exact fluid pressure that the pump is trying to maintain. Operating ranges depending on unit, fluid, tips, anywhere from as low as 1500psi to as high as 3600.
Very common, and very suited to production work like spraying trim in a new home. While your HVLP would likely struggle with the viscosity of an average latex, its what airless pumps excel at.
"Sometimes when I consider what tremendous consequences come from little things, I am tempted to think -- there are no little things" - Bruce Barton
thanks for the explanation. At the price of a paint job, trying to make sure I get a good job done.
thanks joe p
RW covered it well. From my experience, HVLP is typically used for vehicle finishing and other applications where you're trying to cut down on overspray (i.e. wasted paint). Airless, however, seem to see most use in applications such as house painting, etc, due to the fact that they can put out a large fan width and can better handle thicker paints (i.e. latex, etc).
I use both, in the manner mentioned above. HVLP is use for autobody work as well as oil-based paint or polyurethane application on trim/doors, etc. For painting all the walls/ceilings inside houses (w/ latex), my Graco airless is called to action. Same would be true with exterior work. The large fan width the airless can provide allows you to cover a large area quickly, something that I'm not sure HVLPs can really do (though I'm sure there are probably expensive HVLPs out there that could do it).
There is also air-assisted airless....has the same type of pump to pressurise the material, but some atomising air is added at the gun to get a furniture quality finish with lacquers etc.....those systems do use HVLP or similar guns. An airless and air-assisted system look virtually identical. Air-assisted is my favorite setup.....the pump moves the material, so the only air involved is what you are using to atomise the material.....gives the softest spray.Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.