Air Compressor Buyer Guide

The selection of air compressors available is huge, all sorts of different shapes, sizes, powers weights and noise levels; so trying to choose the right one for you can often be a daunting task and you can often buy the wrong one if you do not know what you need.

My first compressor I bought as an impulse buy when I saw it on sale in a store thinking I could use it for all sorts of things. I hooked it up in my garage and only used it to make sure my tires were the right pressure for about 3 months before I decided to buy some tools like the ones that they used where I worked. I was planning to do some work on my car so I bought an impact driver and a ratchet hooked them up to my compressor and set to work - well it had enough power to open a can of corned beef if you started the key by hand first! I learned from this mistake and went off to read up on and educate myself about air compressors!

The following sections will go through the important features that you have to consider when buying.

The purpose of a compressor is to provide volumes of air under pressure, pressure being measured in pounds per square inch or PSI. The higher the pressure the more power a compressor has. However that being said most tools that you are likely to operate will require between 40PSI and 90PSI to operate so almost all available compressors are going to provide the right pressure (I am not talking 12V tire inflators here I hasten to add!)

Most compressors will pressurize the tank to about 125PSI or thereabouts before the compressor turns itself off. Your tools then use the pressure from the tank which reduces that pressure, when the tank pressure reaches a predefined point (100PSI) the compressor will switch back on to pressurize the tank back to 125PSI. The pressure in the tank therefore staying above what you need to operate your tools (but see the next section about tank volume.)

Some compressors will pressurize the tank to 200PSI which means that there is a much larger volume of air in the tank allowing you to use a smaller tank to achieve the volumes you require. There are also some tools such as some of the framing nailers that will operate on these higher pressure to drive nails into even concrete.

CFM or Cubic Feet per Minute is a measure of the volume of air that can be supplied at a given pressure, it is also known as SCFM or standard cubic feet per minute.

For most compressors the available CFM is quoted at 40PSI and at 90PSI and you can then compare these figures against the requirements for your air tools. Each air tool with have an optimum pressure and requirement for CFM to operate efficiently. Failure to meet these requirements will result in a tool that either does not operate or operates for a short period of time at a lesser efficiency.

The following are some examples of CFM requirements;

• Nailer 1CFM
• 3/8 Ratchet 3CFM
• Air Hammer/Chisel 4CFM
• Air Drill 4CFM
• 1/2 Impact Wrench 5CFM
• Angle Grinder 6CFM
• Spray Gun 6CFM

These are typical requirements, you should check the actual requirements of the tools that you wish to use before purchasing your air compressor.

The power of the motor is measured in horse power (HP) and this will be the deciding factor in how quickly the compressor can fill the tank. A 2 HP motor on a 4 gallon tank will have filled in a matter of a few seconds, whereas a 1HP compressor motor on a 15gallon tank will take some time to refill it!

If you are going to be making constant use of your compressor then you will want as powerful a motor as possible to ensure that you do not have periods where you are waiting for your tank to be filled before you can use your tools again which sometimes happens with smaller compressors.

However if you want to use a compressor at home you are unlikely to want one that has more than 1.5HP to 2HP without having to provide dedicated circuits and breakers to power them. Smaller units with 1HP or smaller motors can be safely run even on a standard extension lead.

Most compressors require larger amounts of power when they start up so you may find that your breaker will trip when you use some of the larger compressors so investigate the power requirements and read the reviews before you buy; not all require 120V also, some require 240v or even three phase etc..

If you are going to want to move your unit around then you are going to need to make some trade offs with regards to size and power. If you want a portable air compressor that is small and easily carried then you will not be able to take a 15gallon tank up a flight of steps tucked under your arm!

There are many lightweight small air compressors out there on the market but their power and ability is going to be limited by their size.

You can however buy compressors that are arranged like a wheel barrow with wheels that make them easily maneuverable around a site. Try to choose ones with pneumatic tires however as these are tougher over a site and reduce the vibration and noise of the compressor in use!

A gas powered air compressor is going to be more expensive and heavier than its electric equivalent. However they generally have more powerful compressors for quickly refilling tanks and you can use them anywhere without having to worry about a power supply.

Obviously you cannot use a gas compressor inside due to its exhaust and a gas powered compressor is going to generate more noise and be more expensive to run than its electrical partners.

If you are going to use a compressor in the home or use it as a garage air compressor then you need to consider the amount of noise that it makes. Compressors are generally noisy beasts, most being a 100dB or more (use this article about decibel levels to understand noise), this means that you should use hearing protection when using them, especially in a confined space where the sound is amplified. You also need to consider your family and neighbors and try to choose a quiet air compressor!

smaller compressors are generally quieter than the larger models and some manufacturers are now making compressors that are very quiet, almost silent compressors! There are some that provide reasonable power but only create 60dB of sound which is less than a normal conversation!

Reliability is a big issue with anything that you buy and an air compressor is no different. With the high price of many compressors it is worth doing that little bit of extra homework and checking the air compressor reviews for your proposed purchase.

But remember to actually read the reviews not just look at the stars, many portable air compressor reviews are negative, not because the compressor is defective buy because the user is expecting the performance of a bigger more expensive model!

Remember that cheap is probably exactly that, if it is not an established brand and it is much lower price than comparable models then it is likely not to be as reliable as its competition. That being said it may be perfectly adequate for your uses and can save you some big bucks (but for how long!)

I hope that this air compressor buying guide has answered your questions and helped to educate you about what you need to look for when buying an Air compressor, if you have any questions or comments please leave them below.