The most common types of airless paint sprayers are piston and diaphragm pumps, powered by electricity or gasoline to pump paint mechanically into a spray gun and through the spray tip, which atomizes it into spray. The more versatile piston pump sprayer can handle thicker fluids and longer hoses, while the diaphragm pump is less expensive and works well for transferring a high volume of paint.
As the piston moves up in the piston pump airless sprayer, it creates a vacuum that sucks the paint into the pump or fluid section and, as it moves down, it pushes the paint into a high-pressure hose. The diaphragm pump uses a piston to move the hydraulic fluid that moves the diaphragm, which sucks up the paint and pushes it through the hose and spray gun.
Sprayers with higher horsepower spray more gallons per minute. Sprayers come with gallons-per-minute ratings. Pumps with one-gallon-per-minute or lower ratings work for lacquers, varnishes, solid color stains and typical house paints. Pumps with ratings of one-gallon per minute or more do not work well with lacquers or varnishes, but handle block fillers, masonry paints and rapid drying paints. The time available for the paint job, the thickness of the coating, and the project's size are considerations when selecting the correct type of airless paint sprayer, spray gun and spray tip.