First things first, be honest with yourself, what are you really going to use this compressor for? Is it going to be occasional use in your home garage just to fill the tires on your hot rod, or are you going to be running air tools as you sand down the entire body of your car? This is important because some of those tools can consume a lot of air. And the more air they consume, the larger tank you're going to need, the more horsepower you're going to need. And ultimately, the more input voltage, you're going to need to run that compressor. So let's talk about electricity. In most houses, your home garage, you have 120 volt outlets throughout, that's no problem. Those are the things powering the light bulbs in your garage. Very few of them have 230 or 240 volt outlets. Those are the kinds of things that power your clothes washer, got a washer in your garage, you can unplug it, you can plug in a larger compressor, you can also have a certified electrician come to your house and rewire outlets in your garage to add more power. Again, more power, bigger compressor better tools you can run.
What about Space & Noise?
The next thing you need to think about is how much space do you have in your garage. And how much noise can you make before you anger your neighbors. That's important because a lot of compressors make a lot of noise. And in general, an oil less compressor or a single stage compressor, that thing can make upwards of 90 or 100 decibels. And what is 90 or 100 decibels, that's a loud car going by. So if you plan to work late at night, you need to make sure you can position that compressor in your garage where it's going to be muffled a little bit, while still having a lot of free air around it to keep the thing cool. Does it need to be portable?
There are compressors out there you can buy that have wheels on them, they're very portable. You know, if you've got jobs at the front of the garage or outside of the house, or you're going to help out your neighbors, you might want to look at a compressor with wheels on it. The one thing you need to think about though is that in general, if a compressor has got wheels on it, it's portable, but it's not as large as one that's meant to be bolted on the ground. For example a 60 gallon air intake is perfect for running high volume tools like a dual action sander, or a grinder, that sort of thing, the kind of tool you'll use for long periods of time that eats up a lot of air, this type is not portable. You need to set it down and bolt it down, and make sure it's positioned properly to the proper input voltage.
How will you use it?
So let's talk about applications for an air compressor. There's two type of guys (or girls) we think of at home right now, the kind of person who's going to work all the time on cars. And you're going to use tools a six inch random orbit palm sander, which uses about 15 CFM of air.
A 3 inch cut off tool, at full song will eat up 31 CFM of air, which is a lot. And what does that tell you? You need as much reserve tank and as much compressor power as you can afford.
If you're a person who's at home, and you're probably only filling up tires, or your kids pool toys, or you have the patience of a monk, you don't need a ton of compressor. Because what will end up happening is when you use the tools mentioned above, you're going to stand a bit, and then you're going to stop because they are not going to run very efficiently. And you're going to wait for that compressor to fill up the air tank. And then you can keep going. If you're super patient, you don't need a monster compressor. But if you're going to hurry or you want to work efficiently, or you're going to use tools like sanders or cutting tools, buy as much tank and as much compressor as you can afford.
What do you know about specs?
If know what tools you're going to be running and you know how much air each tool consumes. To choose the right compressor, you should add up the CFM requirements of each tool. If you are going to work at the same time as a friend or co-worker in the garage, and then add 30% to that number. That'll tell you exactly how much compressor you need.
Do fittings & hoses make a difference?
It is very important! You've picked out the compressor, it's at home, it's ready to go to work, and you’ve got brand new air tools. Let's not screw this up by picking the wrong fittings for the wrong hose.
Two fittings can have the exact same thread size, but have radically different orifices. If you were to choose a small one, and you choose the small hose, your half inch drive impact on may not even take the lug nuts off your truck. And the reason for that is, the longer your hose and the smaller the diameter, the less air pressure you have coming into the tool.
Another example, if you have 90 psi coming out of your tank. If you feed it through a three inch hose and a tiny fitting. When you go and pull the trigger on your impact gun. You don't have 90 psi anymore, you’ll have about 75. But if you’d picked the bigger fitting and upgrade to a half inch hose. You can then adjust your regulator and get full air pressure to make that tool work the way the manufacturer intended.
Let's talk applications. Let's say you're at home and you're just going to put some air in the tires on your car, maybe do a home renovation project. You don't need a giant air compressor to do that. Three gallon air tank, a one horsepower engine, maybe a pancake style air compressor, it's perfect for you. If you want to do a little more than that…..If you're really serious about working on cars like we are, you may need a monster compressor.
When shopping for a compressor, there's two specs you want to focus on. The first one is psi, which stands for pounds per square inch. That's a measurement of the force of air coming out of the compressor. That's important, but not nearly as this next spec CFM. That stands for cubic feet per minute. That is a measurement of the volume of air coming out of your compressor. The higher the CFM, the more efficient your compressor is, and the better your air tools will operate. So get as much CFM as you possibly can. Whenever you shop for a compressor. Here's where you need to be careful, there is CFM and there's SCFM. SCFM is corrected to atmospheric conditions, that number will always be higher than CFM. So when you're looking at air tools, you want air tools that consume as little air as possible. So when you're comparing apples to apples, all the tools you look at when you're shopping need to have an SCFM rating. For instance, you look at two palms sanders from two different manufacturers, one may say only consumes four CFM sounds great, right? Wrong. If you look at the other tool, it says it consumes 30 SCFM. Well, when you correct the first one that only had four CFM air consumption, it may actually be more than the one that had 30. Everything has to be standard. Look for SCFM you'll know exactly what you're comparing.