The 10 Best Handheld Air Compressors
Who Has Seen The Wind?
All around us, every second of every day, we're all being pressed in upon from all sides by a powerful force. Its constant pressure affects everything on Earth, and it's partially responsible for the existence of life itself. And it's nearly impossible to escape, from birth to death, except when we're swimming or riding rocket ships into space.
That ubiquitous thing is the air, and it's a blend of a handful of gases. The vast majority of it is made of nitrogen (almost 80 percent), followed by oxygen (just over 20 percent), and rounded out by argon, carbon dioxide, and trace amounts of other substances, while .5 to 1 percent of it is dissolved water vapor. Although oxygen gets all the attention when it comes to human respiration, nitrogen is quite essential to the thriving of more complex organisms, and for a number of reasons.
The highly prevalent nitrogen is a diatomic molecule that's secured with a triple covalent bond that's so strong it can hold up for millions of years. Whereas many planets' atmospheres are apparently made chiefly of more volatile compounds that are quite toxic to biological life, nitrogen's relatively non-reactive properties contribute to the delicate balance that's made living on this planet so remarkable. Because N2 is much more benign than, for example, methane, it can carry life-giving oxygen to our lungs without damaging soft tissue or risking a massive explosion. So the next time you fill a tire or take a breath, consider that most of what you're moving is actually nitrogen, little more than an atmospheric placeholder.
A High-Pressure Situation
Of course, the chemical makeup isn't the only thing air has going for it. Like other gases, and distinctly unlike solids and liquids, air compresses in a way that more dense matter simply cannot. The kinetic theory of gases states that the molecules within this form are constantly moving and bouncing off each other, similar to those making up liquids. In contrast to liquids, however, there's so much space between the particles that they can be forced together and held that way perpetually, as long as there's no low-pressure outlet through which the gas can escape. As the fluid's volume decreases, the individual molecules move faster and faster, as they're moving just as much as before, but in a more confined space. This causes the mixture to push back with a measurable amount of force, and that force is called air pressure.
The common reciprocating compressor is not so mechanically dissimilar from an internal combustion engine, although the exhaust consists of air in a container rather than pollution in the atmosphere. A motor turns a crankshaft that activates one or more pistons that add air incrementally to a reservoir. Ultimately, however, these tools are found in far more places than just a workshop. Various types are used in air conditioners, turbochargers, semi-truck braking systems, sensitive medical equipment, and more. These specialized appliances often utilize a screw-type mechanism to continuously add pressure, an off-center shaft operating much like that of a rotary engine, or dual, fan-like impellers that suddenly alter the velocity and density of incoming gases.
Functional Fresh Air
Because it's so compressible, and because there's quite a bit of it around, pressurized air is commonly used worldwide as an energy storage medium. Air compressors themselves come in all shapes and sizes, designed for powering huge workshops as well as for stashing in the trunk in case of emergency.
For many, the click and roar of a compressor recalls summer days working in the garage, handing Dad's tools and learning about brake lines. Anyone who lives where there are four distinct seasons knows that corrosion can lay quite the beating on automobiles, bikes, and lawn equipment. Pneumatic tools are incredibly helpful in these situations in part because they're durable and easy to swap out a moment's notice. They really shine, though, in their ability to deliver consistent, high torque. The continued pressure of the stored gas makes it mechanically easy to apply massive power to strong equipment like impact drivers and rotary hammers — the kind of power that might burn through a brushless motor or blow an average home's circuits.
Most who aren't incredibly familiar with auto repair conjure up similar images of the iconic flat tire when they hear the term "air compressor." After all, the shoebox-sized models we've ranked could be the difference between reaching your destination on time and waiting hours for a tow truck. Or, the right one could help the kids keep their bikes in tip-top shape, while teaching an early and important lesson about vehicle upkeep.
A benefit of today's advanced component efficiency and battery technology is the ever-shrinking profile of many electronics, and these handheld models are no exception. Some are even designed to strap right to a bike, so you can traverse the wilderness on a dual-sport without fear of a cataclysmic breakdown. And many options are available with power levels previously unheard of in anything smaller than a breadbox. Most of them are built around 12-volt DC inputs, as this size class is generally designed for maximum portability. A handy few work with AC as well as DC power, and features like low-drain work lights and digital readouts are also available.
Whichever you choose, make sure it comes from a reliable company and don't forget to purchase the specific nozzles and attachments that your usage demands. Some options are battery powered, adding a huge measure of versatility, although at the cost of some torque plus the hassle of charging. While none of these will replace your leaf blower or impact hammer, they could very well save the day when you pull a deflated spare tire from your trunk.