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Air compressors can power a variety of work – from inflating a tire to operating a nail gun. Learn to find a compressor that handles your jobs.
Single-stage, piston-type air compressors are the most common models for home use and work well for many applications around the home or workshop. An electric motor or gasoline engine drives a piston which forces air into a storage tank. As the piston forces more air in, the air pressure rises. Once the pressure reaches a specified level, the compressor stops running. As you use the stored air to power a tool, the compressor restarts to build the air pressure back up.
Two-stage compressors have two pistons. The first compresses the air and pushes it through a check valve to the second piston, which compresses it further and delivers it to the tank. These compressors are usually heavy-duty, commercial models that can deliver a greater volume of air at higher pounds per square inch (PSI) levels. They're good choices for continuous use in shops or to power multiple tools at once.
Stationary air compressors are large devices designed for placement in a shop or garage. These are high-horsepower models with large storage tanks to allow for longer periods of uninterrupted use. They typically have a vertical design that reduces the amount of floor space they require.
Portable air compressors have smaller storage tanks and handles or wheels that allow you to easily move them to different work areas. They are more compact than stationary models and come in several styles:
Portable air compressors are good for light, quick applications such as airbrushing and powering most types of nail guns.
Inflators are the smallest compressors. An inflator doesn't have a storage tank, so the motor must run continuously to supply air. This type of compressor can inflate small floats, tires and sports equipment.
Always follow the air compressor and air tool manufacturers' instructions for use, maintenance and safety.
Electric compressors are the most common models. They require less maintenance than gasoline-powered models, are quieter and work in any dry area with a ready electrical supply. Electric compressors are suitable for working indoors. Many home-use compressors function on 120-volt household current, but larger models may have different requirements. A portable electric compressor requires a suitable extension cord, which limits mobility. Follow the manufacturer's specification for extension cords and see Power Cord Safety Tips. Depending on the model, inflators plug into a 120-volt household outlet or a 12-volt vehicle accessory outlet.
Gasoline-powered air compressors are a good choice for outdoor work areas where electricity is limited or unavailable. They typically have more horsepower than electric models, so they can generate greater PSI.
Don't use an electric compressor in a wet or damp area. Don't use a gasoline-powered compressor indoors or in a confined or unventilated area.
The horsepower (HP) rating for a compressor indicates the power output of the engine or motor. Higher horsepower creates greater air pressure, measured in PSI. Higher PSI means the compressor can store more air in the tank, allowing you to operate air tools longer. Cubic feet per minute (CFM) and standard cubic feet per minute (SCFM) describe the volume of air a compressor delivers at specific PSI levels. The CFM value changes as PSI changes. As you lower the PSI output, CFM increases. A compressor with a higher CFM rating can deliver more air and is better suited for heavier applications such as operating air wrenches and framing nail guns.
Compressor manufacturers rate storage tank size in gallons. Smaller tanks — around 4 to 6 gallons — are sufficient for many projects such as airbrushing and operating brad nailers or nail guns. Larger tanks store more compressed air at higher pressures. They're suited for larger tasks that require sustained air flow, such as automotive work and remodeling projects.
While horsepower indicates a compressor's power output, CFM ratings at specific PSI levels determine what tools the compressor will power.
Powering air tools is the key function for an air compressor. Consider the tools you want to use now and those you might need in the future. Examples include:
Most air tools have specific requirements for air volume and pressure. A compressor must meet these requirements for the tool to function properly. When choosing an air compressor, consider the tools you want it to power. Determine which one requires the highest CFM at the highest PSI. Add 50% to the required CFM for a margin of safety, and look for a compressor that meets the requirement. For example, if a tool requires 3 CFM at 90 PSI, select a compressor that delivers at least 4.5 CFM at 90 PSI.
Understanding available air compressor features helps you choose a model that can handle your jobs and simplify your work:
Air hoses must meet the specifications of the compressor and the tools you plan to use.
You can purchase auxiliary air tanks to increase air storage capacity.