Unlike air-powered paint sprayers, which use air compressors to push the paint out with force, airless paint sprayers contain no air compressor. Instead, they use a motorized pump to pressurize and push the paint out of the spray gun's tip. The high pressure built up within the tube atomizes the paint, meaning that it pulls it apart into a fine mist. This creates a smooth finish with a minimum amount of paint.
Airless paint sprayers make fast work of big painting projects, in addition to providing an even finish. They are extremely portable and can carry upwards of a quart of paint, or even pull paint right from a container. They can handle any type of paint, stain or primer, including ones too thick for other types of paint sprayers.
Airless paint sprayers all have a hose, gun, tip and pump. The hose has a wider end, which goes into the paint, and a narrower end, which connects to the nozzle. The "gun" is what allows the painter to control the flow of paint. When the trigger is pressed, a valve opens to allow paint to flow through the tip and onto the surface. Varying tip sizes and shapes control the amount of paint that comes out. There are two types of pump: piston and diaphragm. The former can pump thicker paint, while the latter is generally less expensive.
Located in the gun's spray head, the pump gets hydraulic power from the motor. The piston first moves up, creating a vacuum and therefore drawing paint up into the chamber. Then, as the piston moves forcefully downward, it shoves the paint through the hose and out of the narrow nozzle. It is this motion that results in such high pressure that the paint is atomized.
These pumps use pistons but do so slightly differently. The motor allows the piston to move up and down, but in this case, as it pumps, it quickly expands and contracts the flexible diaphragm. The piston's upward movement creates a vacuum, drawing the paint into the pump through the inlet valve. Its powerful downward motion then compresses the diaphragm, pushing the atomized paint out through the tip and onto the surface.
To control the direction of the paint, there are check valves in place to ensure that it moves from the source out through the tip instead of falling back into the paint container.