Air Compressor Buying Guide

There are two types of air compressors: portable and stationary.

• Portable air compressors come in a variety of shapes and sizes. Smaller models are light enough to carry. Larger models include wheels for mobility. Portable air compressors are available with tanks in different sizes, ranging from two gallons to 30 gallons.
• Designed to be bolted into a fixed area, stationary air compressors attach directly into a building's electrical circuit. They typically feature 60 to 80-gallon tanks and offer motors that are between 4 and 10-horsepower. They are a great investment for a garage or workshop.

Whether portable or stationary, the best air compressors are available in one or more power sources: electricity, gas or a battery pack.

Easy to use, electric air compressors simply plug into a regular wall outlet. Most run on standard household voltage, between 110V to 120V. However, compressors with motors that exceed 2HP can require a 220V to 240V outlet.

Electric compressors are the ideal choice if you need a quiet air compressor or a automatic start-stop air compressor. Since electric compressors don't emit fumes they are perfect for areas with limited ventilation. This makes them the best home garage air compressor.

Tip: Powering an electric compressor with a generator can damage the motor.

Gas-powered air compressors are usually portable and work well for those places where there's no electricity. They are commonly found at job sites, on farms or other outdoor spaces. The high-pressure output of a gas-powered air compressor makes it ideal for heavy-duty projects and tools such as nail guns, sanders and paint sprayers. These types of air compressors are more budget friendly but have fumes and can be noisy.

Compact and lightweight, cordless air compressors use a rechargeable battery platform. Since there's no cords to get in the way, cordless air compressors are easy to carry around and use. This makes them ideal for projects that require more flexibility such as working on a roof or in small spaces.

Cordless air compressors are quieter and work equally well indoors and out. However, due to their limited power, even the best air compressors of this type work better for smaller projects than for larger ones.

Compressors generally have horsepower ratings between 1 1/2- to 6 1/2-HP. However, it’s the standard cubic feet per minute (SCFM) or performance rating that reflects the air pressure a compressor generates inside its tank. A tank's SCFM determines just how much power the compressor will provide to a tool. This power is measured in pounds per square inch (PSI). In addition, the tools powered by air compressors also have their own SCFM ratings that indicate the air flow or pressure a tool needs for top performance.

Here's how to gauge the minimum compressor SCFM rating you need for your air compressor:

• Examine the SCFM requirements of all the tools you intend to use.
• Multiply the highest tool rating by 1.5 to get the minimum compressor SCFM for your needs. Since actual SCFM varies during compressor operation, this number will give you a little buffer.
• If you expect to operate multiple pneumatic tools at the same time, you'll need more power. Calculate the minimum SCFM compressor rating by adding up the SCFM requirements for each tool that you'll use simultaneously.

Smaller tools usually require 0- to 5-SCFM. Larger tools can require 10-SCFM or more.

• Most light-duty home compressors are designed to power only one tool at a time. Light-duty compressors generally have 90-PSI, which is typically sufficient for powering pneumatic tools for simple, household tasks.
• More powerful, professional-grade compressors may generate 150-PSI or higher and can handle multiple tools.

A smaller tank size is a good choice if you intend to use a tool intermittently. For example, tools that require only quick bursts of air drain the tank much more slowly. For tools like pneumatic brad nail guns or finish nail guns, a 2- to 6-gallon tank is sufficient.

If your pneumatic tool requires a high volume of continuous air, then you should consider a larger tank. It’s best to have a large enough tank with a compressor pump that exceeds the SCFM requirement of the tools. This will allow the compressor time to cool between cycles.

There are two air compressor pump types: single and two-stage. You can also choose between oil-lubricated or oil-free. In addition, there are other pump features that can protect both you and the compressor from harm and unnecessary wear and tear.

Below are the types of air compressor pumps you can choose:

• Single-stage air compressors can have one or more cylinders producing compressed air at the same output pressure.
• Two-stage air compressors. The first-stage cylinder(s) feed air to a second-stage cylinder that further compresses the air. The second stage cylinder(s) typically increase the tank pressure to around 175-psi. The benefit is more air stored in the same size tank, allowing tools to run longer. This is useful for high-demand work, such as continuous tool operation in an auto shop.
• Oil-lubricated air compressors require oil to operate, just like a car or lawn mower engine. The oil lubricates the moving parts in the pump to prevent excessive wear. They are generally larger and heavier than oil-free models. Plus, oil must be monitored and changed to prevent premature failure.
• Oil-free air compressors typically use special piston rings. These rings are made from a material like what's used in non-stick frying pans and to lubricate the cylinder. Oil-free compressors are a much smaller, light and a popular choice for both homes and job sites.

Once you've discovered the best air compressors for home use or workshop use, it's time to add a few key air compressor parts and accessories:

• Installing a pressure regulator on your air compressor will help you know precisely how much air flows from the compressor. You can easily adjust the pressure up or down according to the needs of the job.
• Trade out the air hose with a longer option for extended reach.
• Adding a desiccant dryer to the air compressor protects your equipment from the moisture contained in compressed air. Moisture can cause damage to pneumatic equipment over time.
• An air filter protects pneumatic tools from water, oil and dirt as you're using the air compressor.
• Air compressor combo kits include an air compressor with key accessories or a compatible pneumatic tool.

When deciding between different types of air compressors, look for features like:

• An air-cooling system that cools pumping machinery and extends motor life.
• A thermal overload switch which automatically shuts off motor if it overheats, increasing tool life.
• A label stating that the unit meets the standards of the ASME (American Society of Mechanical Engineers) for high-quality materials and craftsmanship.
• A roll cage that protects the compressor from being crushed or battered on the job site.
• Air compressors with universal quick connectors make it easy to trade out tools.

After you've chosen the best air compressor for your needs, keep it performing well with these tips:

• Never exceed the recommended pressure for the job or the tool.
• With oil-lubricated compressors, always check the oil level to ensure sufficient lubrication.
• Make sure safety relief valves are not covered during use. Otherwise, air will escape automatically if the pressure is too high.
• After each use, open the drain to get rid of any moisture that's accumulated.
• Always consult your owner's manual for specifics.