How to choose an air compressor

A compressed guide

Basically, air compressors work by mechanically squeezing sucked-in air through internal components to create a force that can power air tools. When the maximum air pressure has been reached, and has had time to cool down, one duty cycle has been completed.

A reasonable guide to prevent overuse, and potential deterioration of your air compressor, is to ensure it's only in operation for 60 per cent of any timeframe, and is therefore turned off, and cooling down, for 40 per cent of the time.

All compressors need to generate enough air flow, at the right pressure, to power the air tool or tools they're connected to. The volume of air that compressors produce is measured in litres per minute (l/pm) and is known as the “Free Air Delivery” or FAD.

If your air tool consumes 100 l/pm, your compressor would need a FAD rating of, at least,100 l/pm. And, if you want to simultaneously power multiple air tools, you'll need a minimum FAD rating of the total of all the tools' FAD ratings.

Tools of the trade

There are various types of air tool that you can power using a compressor. There are nailers and staplers, sanders and grinders, spray guns and tyre inflators, just to name a few.

Ask yourself, how many different air tools could you possibly need to simultaneously power with your compressor?

By knowing the type and size of tools you want to use, and the length of time you want to continually use them, you can make a far more measured assessment of which air compressor will work best for you.

Another consideration will be the volume of the reservoir or tank. The larger the capacity the longer you'll be able to leave your compressor between charges. Certain air tools will require a much higher volume of continuous compressed air – the larger tank sizes are best in these situations.

Air tools that you use more intermittently should operate with the smaller sized reservoirs. 

Narrow your options

There are many different types of air compressor available to buy, which means there are multiple factors to weigh up in your decision making.

For a start, do you want a petrol or an electrical compressor? Petrol compressors are only suited to outdoor work, whereas electrical machines can be powered anywhere, as long as you have enough amps to operate them. This can be more complicated, than you'd first imagine, as they can run off 15amp, 10amp and even 3-stage electricity.

Then there's the question of capacity vs portability. A smaller tank size will obviously run out of air earlier, but it'll be less bulky and easier to move around. Larger air tanks will last longer, allowing you to operate multiple tools simultaneously, but what you might gain in operating power you may lose in manoeuvrability.

You'll also have to choose between a belt or direct drive machine. Belt-driven compressors are often more flexible, cheaper and easier to maintain, but are not suited to harsh conditions. Direct drive compressors, however, are more energy efficient and robust.

There's also a decision to be made around silent versus non-silent (or regular) air compressors. Silent air compressors come with added noise-damping properties which can decrease, and sometimes eliminate, all mechanical noise. Silent air compressors are best suited to smaller or open planned work set-ups.

Finally, you'll have to work out whether you want to go down the oil or oil-free route. Oil air compressors use a piston to draw in air, which is then compressed in a storage tank. To work well the piston chamber needs to be lubricated and maintained with oil. Oil-free air compressors don't require the same maintenance because they are sold pre-lubricated. 

Quality and quantity

Air quality is another important consideration. Because a compressor's air flow can be compromised by moisture, dust and oil particles, the quality of air will differ from machine to machine. If you require “clean” air for a specific task, consider using compressors that have been fitted with moisture and particle filters and/or oil-free pumps.

The following chart lists common air tools and gives a guide of their typical air consumption and the total pressure they operate at:

(n.b. this is a guide only and you should check the operator's manual or website)

Find the right air compressor for you

If you need more help deciding on the best air compressor for your tasks, take a look at our wide range of compressors or speak with one of our helpful team.