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I was thinking to buy an air compressor and place it in my garage. I hate to look for change when i am at the gas station and i usually end up spending more than usual as some idiot has parked his car right in front of the air pump. I have no idea if this is actually doable or not. What kind of brand or qualities i should look for.
Can someone please throw some light on this? What kind of air compressor should i look for?
Also it will be great if the compressor runs on Electric.
You don't really need an "air compressor" in the sense that you don't need something that has a tank and is designed for use with tools. All you really need is sometimes called a "tire inflator", obviously it is actually an air compressor but it is very different from those listed by Jeff's answer.
I have seen two basic types.
There are 12V versions that are designed to simply plug into the cigarette lighter outlet in your car. This is nice because you can refill the tires anywhere. When I had a slow leak in my tire I put this thing in the trunk and drove to work, then before leaving work I would top off the tire again. It worked fine for the day or two until I could get to the shop for a new tire. Usually these are pretty cheap.
The other version is designed to plug into a household receptacle. These seem to be a little more expensive than the 12V versions.
Sometimes you can find these types of tire inflators with standalone battery jumpers attached so you can also use it to jump your car. I would skip that feature unless you think you would actually use it.
The answer is a semi-useless "It depends." Tank size, oil vs. oil-free, CFM, etc. Most compressors will come with a little kit (usually sells for ~$20) that has a length of hose, an air chuck, and some air tool fittings.
I think the most important thing to pay attention to is CFM. This tells you how much total flow the compressor can provide on a constant basis, and also how fast it will fill the tank. Horsepower is often loosely related to CFM. Remember that 1HP = 746 watts, and thus you can't run more than 2 HP on a 15 amp circuit (1800 watts - line loss).
Larger tanks allow a larger reserve and sometimes running tools that take higher flow for short periods than the compressor can provide. With smaller tools, they allow the compressor to spend less time running. Most consumer compressors have a limited duty cycle (50% is common) and aren't meant to run constantly. Don't expect full duty cycles until you get something with greater than 5 CFM. Tank size usually corresponds somewhat to compressor power.
Oil free is usually regarded as louder. Belt driven compressors run at lower motor speeds and are usually quieter than direct drive. Don't worry unless you're painting or some other specialist application.
Who knows the PSI / CFM? I keep one with my motorcycle for dealing with low tire pressure. These things take a while, but they work. I find myself using a real air compressor is worth it if I'm doing anything more than just topping up tires once a month. Noisy and slow, but portable and cheap. ~$20
DO NOT BUY THIS
It has a 3 gallon tank like next air compressor, costs about the same, and has 1/5 of the flow. That means it takes five times as long to come to pressure and 5 times as long to do anything useful. Further, the cutoff pressure is very close to the operating pressure. $75 - $130.
The smallest I would buy is this:
It's great for inflating tires and has been good enough for me to use when seating the bead on motorcycle tires (I change my own off the rim). It's damn near useless for tools. Anything that runs for more than a moment is going to make you want something bigger. Air ratchets and die grinders just won't work on this machine. Tank pressure is only 125 psi.
About $80 on sale, $140 normally.
Might be acceptable for a 50% duty cycle on many air tools. Tank pressure is 150 psi, and it's a big reserve. Useful for more minor tools and probably the deep end of the "cheap" spectrum. $250 - $300.
Starting to get really useful. Will run most things, and possibly even allow painting with an air sprayer. This is the most you can put on a 120 volt 15 amp circuit. That circuit should be dedicated to just running the compressor. This is a belt drive instead of a direct drive. $420 - $530
After this, you start looking at dedicated 220 volt installed devices or engine-driven, $500+ (quickly several thousand) price tags, and a lot of things that only the most dedicated garage junkies would consider installing. Useful if you're going to use an air-driven paint gun or are running a shop.
you don't need a compressor to inflate car tires a simple bicycle pump that fits on mountain bikes will work (they use the same valves) take one with a long stroke and/or large piston diameter and a pressure gauge and you will be set
a car tire typically needs around 30 PSI (check the markings/manual) while a city bike needs around 50-75 (so don't worry about whether it can handle it)
there is more air to move into the tire with a car before you get up to pressure (hence the suggestion for a larger piston), but when you are only topping up it should be sufficient, if a bit tiring on the arms/legs (depending on whether you have a foot or hand pump)
At my work, we have one of these for basic blowing/dusting/inflation-type tasks:DeWalt 1-Gallon 135PSI Trim Compressor
It's not big or fancy, and it doesn't have a great reserve, but it'll work just fine to inflate your tires, and it should be serviceable for driving a medium-duty nailer/stapler.
My father-in-law has this one: Campbell-Hausfield .33HP 2-Gallon 100PSI Compressor
We used it with the included nailer to nail up some crown molding in my kitchen. Worked just fine driving 2" pins. Compressor was a little loud in an interior space, and it took a while to get up to pressure.
Neither of the above two are going to drive an impact wrench, so if you're planning on doing anything more serious in your garage or job site than inflating tires and blowing dust out of crevices, you'll want something more substantial, and you'll probably have to plan for it in the electrical system of your garage (like adding a dedicated 220V 20A breaker for the "shop air").
This is probably the very least you'd want as a portable setup for serious air tools: DeWalt 1.8HP 4.5-gallon 200PSI Compressor. It will inflate your tires no problem, and will drive pretty much any nailer you want to use. It has the bare minimum airflow for your average impact wrench, and MAYBE your smaller air hammers/chisels, like for lifting floor tile. I wouldn't be trying to break up my sidewalk or slab foundation with a setup like this.
This one would be typical for an installed garage compressor with one or two guys drawing from it for pneumatic wrenches, and is almost certainly more than you need: Kobalt 3.7HP 60-Gal 155PSI Air Compressor/Tank
As others have pointed out, compressors are available with a huge range of capabilities, from a basic tool to pump up tires (expect the really small/cheap ones to be slow) to far more.
I'll try to point out that a compressor has many other uses, in fact, I'll wager mine is one of the most useful tools in my shop, certainly the first thing I turn on in the shop after the lights go on. It can drive an impact wrench, pump up tires, blow out water lines to winterize plumbing. Air nailers are great tools, making some repetitive nailing tasks go amazingly fast.
I use it to blow the sawdust from my hair/clothes after a long time in the shop. We get leaves stuck in a difficult to reach crack between the deck and our house. If you leave them there, they rot and invite ants in, so I must blow them out several times per year. A leaf blower simply won't cut it, but the stream of air from my air hose works nicely. When I must do some light milling on my mini-mill, a continuous stream of air across the bit both keeps it cool and blows the chips out of the way. This fall I used an air hammer to break up a large amount of cement into small enough pieces to move.
All of these things and more are doable with a compressor. I've plumbed my garage for air, my shop, even run a line down to the basement, ball valves shutting any section of line off when not needed. When 200 feet of hose won't reach, I disconnect the temporary tank I have hooked inline with a quick disconnect fitting, and I've got 10 gallons of air available for use anywhere I want to carry the tank.
My point is, you may find other uses for a compressor once you look around. Some tools may not work on small compressors, so look at the air requirements for any tool. For example, some tools are marginal on my compressor except in short spurts, which is only rated to provide 5.8 CFM. Other tools would not run at all.
(For anyone who decides to add plumbing for air, copper lines are a very good choice. Hard plastic lines are dangerous, as they can shatter. Flexible air lines are cheap enough and easy to run anyway.)
