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Taking to the Air in Your GaragePrintable version
Degree of DifficultyModerate
Moderate
Estimated Time120 minutes
120 minutes
So, if you’re ready to go pneumatic, here are some points you’ll want to ponder:

The electricity:
Wait, aren’t we giving up electricity for air? Yes, but your compressor needs a power source. We’ll talk about the compressor in a moment, but first you need to make sure your garage is equipped to handle the power demands. Some compressors, especially large-capacity models, require a 220-volt power supply. Others give you the option of running the compressor on 110 volts or 220 volts once you have made some minor wiring changes, which are typically outlined in the owner’s manual.

What’s the difference? It comes down to the following electrical equation: amps x volts = watts. Amps represent the volume of electric current, volts the electromotive force driving the current, and watts the power generated by the current. For a given wattage, as volts rise, amps drop.

Here’s an example: your new air compressor is rated at 3000 watts (check the box, the directions, or the label on the compressor motor for the actual number). If you plug it into a 110-volt outlet, it will draw a peak of 27 amps. That’s a lot of amps. It could be more electrical capacity than your garage circuit is wired for. If you plug it into 220, it will draw only about 14 amps. That’s a big difference. It means smaller wires, less heat, and less wear-and-tear on the electric motor.

Definitely consult with an electrician to determine your individual power needs, but know that ensuring you have enough electrical capacity is the first step in converting your garage to air.

The compressor:
This is the biggest single purchase, and the heart of the system, so pay attention and shop around. (The photo at right shows a 5 hp/25 gallon compressor that offers good sound shielding, easy to use air pressure controls, a condensation drain cock, and the option of running at 110 volts or 220.) The air compressor breaks down to four basic components: a cylinder with a piston that pumps air (larger compressors have two pistons), an electric motor to drive the piston(s), a tank that serves as an air reservoir, and a pressure regulator. Many compressors sold for home handyman use are oil-free, meaning they do not require an oil reservoir that must be regularly topped up. Professional-grade compressors, because they tend to work harder, depend on an oiler. Longer life is the upside of an external lubrication source, but you have to continually check and maintain the oil level.

A 5 hp/25 gallon compressor .
Buying a compressor is like buying a computer; you want the best one you can afford but you don’t want to overpay for capacity that you will never use. Compressors range in price from a couple hundred dollars to a couple thousand depending on the following factors:
Power. This is typically expressed in horsepower, but flagrant rounding up by the compressor manufacturers is common. Do your own math: 1 horsepower equals 746 Watts, so if the box claims 5 horsepower but only 3200 watts, you know the horsepower rating is more like 4.3. The higher the horsepower, the better able the compressor motor is to replenish the air tank. Larger tanks (see the next point) require more powerful compressors to keep them filled.
Tank size. Compressor tanks can range from 5 gallons to 500. How much do you need? It depends on what tools you will use. Small hand tools such as a die grinder or an impact wrench consume relatively little air, while constant-flow tools such as a paint gun or a bead-blast cabinet can leave a smaller compressor breathless. In general, any compressor up to 25 gallons is adequate to power hand tools, while 50-100 gallon tanks are the minimum requirement for painting and blasting.
SCFM. This is the Standard Cubic Feet per Minute rating, often expressed as CFM for short. CFM measures the volume of the flow of air generated by the compressor at a given pressure (it varies as pressure rises and falls, and also with temperature, so the Society of Automotive Engineers uses SCFM, which fixes the pressure at 14.7 psi and temperature at 60ºF). In other words, if someone measures how much air you blow out your nose during a sneeze, that is your CFM, but not your SCFM. Volume matters to air-tool operators because the higher the CFM rating (it generally rises with horsepower and tank volume), the more work the compressor is able to do.

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