Each year at Christmas time I expect there are lots of folks planning to buy their brother, hubby, wife, cousin… whomever, an air compressor for Christmas. How do you know what the air compressor you are planning to buy is good for?
Is it the right air compressor for the recipient?
Take the little Central Pneumatic air compressor shown in the photo, as an example, if you will.
This air compressor is designed to run on a 120 volt power supply, has a few gallons of compressed air storage, and might even be oil free in operation, meaning the owner will not have to worry about checking or adding oil.
But, what is this compressor good for?
Well, this type of air compressor will run for a minute or two, and build up 100-120 PSI worth of compressed air in the tank. And, when you connect your air line to the discharge coupler (the discharge coupler is the the chrome ringy thing shown on the right of the black housing in the image) the air in the tank will run any air tool that needs up to 100-120 PSI of air pressure to work properly.
But… 🙂 you knew a but was coming, didn’t you?
What size of air tool?
Depending on the air tool the user is attempting to run with this compressor, the tool may run for a few seconds to maybe a minute before the air pressure in the tank drops to below the cut in pressure setting and the compressor kicks on to build more air pressure in the tank.
This is good. This is what is supposed to happen.
The problem arrives when the air tool is using way more air than the air compressor can make. The compressor will keep running then, your air tool will be using more air than is available, the air supply will continue to fall, and eventually your air tool will stop – though the air compressor will keep running like mad, trying to build the tank pressure back up to the point where the pressure switch will trip off and shut down the compressor.
An air compressor with a couple of gallon tank size will not run an air ratchet, air drill, air sander, air grinder… or virtually any air tool that you run on a continual basis to do work. This size of air compressor is just too small.
Did you know that you will get around 90 PSI of air pressure at 4 CFM for each horsepower of electric motor?
Did you know that a high demand air tool will consume much more compressed air than one horsepower of air compressor motor can deliver?
So, what is a small, fractional horsepower up to a 1.5 HP sized air compressor good for?
Oh yes, it will run your ratchet for a few seconds, but you won’t be happy with that.
What this type of DIY air compressor is good for is air tools that use just a “shot” of air to run. You know, the air nailer, for example. You pull the trigger on the air nailer, it goes “kathunk” and then the air use stops, no more air flows, until you pull the trigger again.
This compressor is also good for airing up tires, filling up a beach ball, will eventually fill an air mattress (careful you don’t blow the air mattress up due to too high pressure), blowing dust off of things, and jobs like this.
If you want to do serious work with an air tool, you will want to get a serious air compressor. You would want at least a 3+ horsepower air compressor, one with a 30+ gallon tank as a minimum, and one with a motor that will run on 240 VAC power. There just isn’t enough oomph in a 120 volt power supply to drive a compressor motor big enough to compress a lot of air, and that’s a fact.
So Merry Christmas to you all. Buy lots of air compressors, won’t you?