When you're buying an expensive piece of equipment, like an air compressor, you want to know exactly what you're getting and whether it will fulfil your needs which is why we've created this brief Air Compressor Buying Guide to help you make an informed decision.
Air Compressor Buying Guide
When you're buying an expensive piece of equipment, like an air compressor, you want to know exactly what you're getting and whether it will fulfil your needs, which is why we've compiled this brief Air Compressor Buying Guide.
In this guide we hope to answer all of your Air Compressor related questions but if we've missed something or you're still not sure please contact our customer service team who will be very happy to help.
What is CFM?
CFM stands for 'Cubic Feet per Minute' and is used to measure the air displacement or volume of air that an air compressor can supply. There is often two different CFM measurements given - 'Air Displacement' which is the theoretical value and 'Free Air Delivery (FAD)' which is the actual, real-world value. Most air compressors sold online will display the theoretical measurement in their name but we believe this is misleading so we have decided to list our products using the 'Free Air Delivery (FAD)' measurement since this is more informative but if you would like to know the theoretical value this can also be found in every air compressors description.
How much CFM do I need?
This varies depending on your tool but to find out what you need, you should first consult the manufacturers website or your tools manual to find the 'Required SCFM' (Standard Cubic Feet per Minute) or 'Air Consumption' (usually given in L/min) for each of your tools. Once you have found these measurements, you need to create a buffer between your tools thirst and the compressors output to avoid damaging your compressor and ensure a safe working environment.
We recommend multiplying the 'Required SCFM' / 'Air Consumption' by at-least 1.25 but if you would like to be extra safe or create a greater buffer for future tool purchases multiplying by 1.5 may be appropriate.
Example - This Mirka 150mm Random Orbital Sander with Dust Bag has an Air Consumption of 481 L/min (17 SCFM) and since 481 x 1.25 = 601.25 L/min (21.23 SCFM), we would recommend an Air Compressor with at-least 21.23 CFM Free Air Delivery.
Additionally, if your air compressor can power more than one tool at once (i.e. twin outlets) you should add both tools 'Required SCFM' figures and then perform the buffer multiplication.
What type of Air Compressor do I need?
The most common types of air compressors are 'Direct Drive Air Compressors' and 'Belt Drive Air Compressors' which are both great for DIY, trade usage and industrial applications.
Direct drive air compressors have the motor attached directly to the crankshaft which means they have very few moving parts - this makes them very hard-wearing and great for rougher applications but does mean they produce more noise. Belt drive air compressors use a belt to transfer energy to the pump from the motor - this means they make less noise and can run smoother than direct drive air compressors which will improve efficiency. However, belt drive air compressors will eventually need the belt replaced and are less rugged than direct drive compressors since they have more moving parts.
If you need a rugged air compressor which can cope with rougher applications or outdoor use and noise isn't an issue then we recommend a Direct Drive Air Compressor.
If you need an efficient and quiet air compressor that will remain sheltered in a workshop or garage then we recommend a Belt Drive Air Compressor.
However, this doesn't mean that a direct drive air compressor couldn't perform a belt drive air compressors work or vice versa but instead that they each have their own strength's and will perform best when used in a way that takes advantage of these strengths.
An often forgotten type of air compressors are 'Screw Air Compressors' which are great if you require a constant flow of air power for industrial applications since they are incredibly quiet and efficient but are designed to fulfil very specific professional needs.
What size of Air Compressor Tank do I need?
There are no specific rules when it comes to the tank size of your air compressor but it will determine how long you can use your air powered tools for before you need to refill your tank. Different tools will drain your tank at varying rates which is why we recommended that you choose an air compressor which will store at-least five times the SCFM rating of your tool (or you can divide the L/min rating by 5.66) since this will allow you ample operating time before regeneration of the air compressors tank is required.
Example - This Mirka 75x100mm Orbital Sander with Central Vacuum has an Air Consumption of 16 SCFM (453 L/min) and since 16 x 5 = 80 (or 453 / 5.66 = 80), we would recommend an Air Compressor with at-least an 80 litre air tank.
Please remember, your air compressor will need to cool down between each tank refill to ensure a safe working environment and to avoid damaging your air compressor.
Should I buy an Electric or Petrol Powered Air Compressor?
This again depends on how how and where you intend to use your air compressor. If you need an air compressor that can be refilled remotely (i.e. no mains power) then you should choose a petrol powered air compressor but if you'll be using your air compressor near an electricity source then an electric powered air compressor would make more sense since these can be refilled indoors unlike the petrol alternative which can only be refilled indoors if the area is well ventilated.
It is also important to note that some electric powered air compressors will require a power source with a specific voltage and/or ampage (i.e. 3-phase electric air compressors) which can improve their efficiency dramatically and will save on running costs in the long term but will require a higher up-front cost since they will need to be professionally installed.
Oil-free Air Compressor vs Oil Lubricated Air Compressor - whats the difference?
An oil-free air compressor doesn't require any lubricating oil which means it will require less maintenance and will have no messy clean-up but it may not last as long since over time the parts will experience more friction. Some applications will also specify that an oil-free air compressor should be used but these are not that common. An oil lubricated compressor will require regular oil top-ups but will often run more efficiently and have a longer life.