Air compressor FAQs

We have listened to lots of compressor FAQs over the years and we’ve put together a guide to help you understand what you are buying and how it works. We hope it will help you make sense of the terms we use in our product descriptions and help you choose your new compressor.

Compressed air is a source of energy that can be stored in a vessel (tank) and in distribution pipe work. The air compressor draws air from the atmosphere and then compresses this air to between eight and ten times it’s normal pressure. During compression the molecules in the air speed up and this creates our energy source, which is then stored in the tank or pipe work ready for use. Our FAQ helps to explain this in more detail.

Q. What is pressure?

Q. Why are compressors sometimes fitted to a tank?

Q. How do I know which power supply to choose?

Q. What does the “capacity” of a compressor mean and how do I choose?

What is pressure?

Pressure is a measurement of force. We measure pressure by comparing it to our normal atmospheric pressure, which is 1 Bar or approximately 15psi. Most air tools etc. operate at a pressure between 2 Bar (30psi) and 6 Bar (90psi). Most car tyres are inflated to between 1.5 – 2 .5 Bar (22 – 35psi). Most air tools including drills, sanders, nailers and chisels etc. will operate at a pressure of 6 Bar (90psi) approximately.

Spray painting requires lower pressure than some air tools. If you forget to lower the pressure you will over-atomise the paint or material you are spraying. If that happens, the material gets lost to the atmosphere instead of landing on whatever you are painting.


Why are compressors sometimes fitted to a tank?

The air receiver or tank stores the compressed air and gives you more control over it. Most compressors include a device that keeps pressure at a pre-determined pressure range. This allows the compressor to operate automatically as the air is used, switching on and off accordingly. The air receiver will also be fitted with a safety device to prevent over pressurisation; a means of draining condensation; and various outlet sockets.

The size of the air receiver (usually measured in litres) will normally be proportional to the size or capacity of the air compressor that is fitted. Some air compressors (e.g. Compy O15) come without an air receiver and these must be switched on/off manually while you are using them.


How do I know which power supply to choose for my air compressor?

There are a few questions to ask yourself when you are deciding on the size of your air compressor. All the compressors we recommend for hobbyists, DIY and home run off a normal domestic electricity supply. In the Additional Information tab you will see phrases like “single phase”, “230v” or “13amp plug”.

ABAC sells compressors of all different sizes so can offer you three phase electric air compressors, as well as diesel and petrol driven compressors. These are generally too expensive for DIY and hobby use but please ask our LiveChat team if you’d like to find out more.


What does the “capacity” of a compressor mean and how do I choose?

The capacity of your air compressor is measured in Cubic Feet per Minute or CFM. This is generally the most important thing to look at because it tells you how fast your compressor can deliver air – and how much air you need each minute will depend on the tools you are running. So, it’s useful to think about the types of tools you want to run and check the recommended CFM for those tools when you choose your air compressor.

If your compressor is too “small” it won’t be able to keep up with your demand and you will need to stop work while it catches up. However, an air compressor with a big receiver can store compressed air. Basically, the machine keeps on compressing air even if you take a break from using your tools and then it stores this compressed air in the receiver. So you might find that a lower capacity compressor is up to the job if you have a big enough receiver.

All of the air tools or accessories that you use require both a certain pressure of air and a certain volume of air to be supplied. As well as CFM and receiver size, the amount of air your compressor produces will depend on the power of the electric motor and the type of compressor fitted. The motor size of our DIY (portable, small and entry level) compressors is big enough for all the normal home, hobby and garage uses. They are generally direct drive type compressors but you will need a Baseline belt driven compressor for spray painting.

Our DIY compressor range is aimed at situations where you only have one air tool running at a time. ABAC has a wide variety of pro compressors which can run several tools at a time so please ask our LiveChat team if you think you need a higher capacity compressor. If you need a larger compressor, a simple guide is to take the tools that require the most volume of air and multiply these by the number of people who could be using these tools at the same time. The frequency of use is an important factor. When air tools are used continuously you need a larger compressor but if you run tools intermittently the air receiver will provide a valuable buffer of stored compressed air. We can help you choose the right compressor for you, whether you need something big or small. Just ask the LiveChat experts!