Choosing an Air Compressor for Airless Paint Sprayers and Spray Guns
Air is the key factor in using airless paint sprayers and spray guns and the largest cost is often the air compressor that is required to provide the compressed air for your spray gun or airless paint sprayer. When evaluating a compressor the key is to know your equipment’s air requirements and your application needs. First will cover the air requirements of airless and spray equipment and then we will cover things to consider about the air compressor itself.
Between spray guns and airless paint sprayers, spray guns use a significantly lower volume of air. When it comes to a compressor, the volume of air is what is most important, as almost any compressor will provide the pressure painting equipment needs. Typically the volume of air the compressor provides is what increases the cost of the air compressor and is important to think about which equipment (airless or a regular spray gun) is better for your application. To better understand which is right for you check out our article on when to use conventional vs airless spray equipment. After deciding on your proper spray equipment you can then be sure of the right size compressor. As a general rule of thumb for a single Spray Gun you should have around 30 CFM. However, you can get away with less with the proper spray gun (around 6 CFM). The limitation will be that you will not be able to atomize heavier coatings as well due to the low CFM air cap that will have to be used to conserve CFM. With air driven Airless Paint Sprayers air requirements will depend on the fluid output and pressure of the pump. To be safe usually around 100 CFM to 130 CFM is good to have available for an Air driven Airless Paint sprayer (electric and gas airless sprayers do not need a compressor). If you use a compressor that is small you have to make sure you properly mach your spray equipment so that it doesn’t require a lot of air. If you have a spray gun that uses more air than your compressor can supply, you will notice problems where your spray pattern will not be consistent after spraying for a while. The fix for this issue is to increase your compressor size or use a large storage tank and occasionally stop spraying so that the storage tank has the chance to rebuild pressure and volume.
In addition to having enough volume of air you have to consider the type of compressor to use. For spray equipment, there will primarily be two kinds of compressor you will use, first is a reciprocating compressor and second is a screw type compressor. Their pros and cons can be read about here. Compressors come in single and two stage formats, the difference is in the volume of air per Horsepower they will deliver. A two stage compressor will provide about 4 CFM per horsepower while a single stage compressor will only provide about 1 CFM per horsepower both will provide about 100 PSI of pressure, but we need volume of air more than pressure. For this reason, when considering a compressor for spray equipment it typically requires a two stage compressor to provide enough CFM. In addition to the style of compressor, you also have to evaluate where you will be working. If your working in a manufacturing plant, then a electric indoor compressor will most likely be appropriate. However, if you will be working in the field, you will typically need a two stage gas driven air compressor also called a tow behind compressor. Overall, by being aware of your compressed air needs and cost, you can best prepare for your current spray equipment needs and plan for future potential growth as well.
Photo courtesy of Chris Bartle