Understanding Compressor Specifications



If you are looking to buy a new air compressor, being faced with the prospect of deciphering the myriad of product specification sheets can be daunting.  With so many makes and models available, all quoting different figures, it can be hard to make a true side by side comparison.  Getting to grips with the basic specifications can help to make the process of selecting a new air compressor a lot less confusing so here is a handy list of the main things to focus on.


Go with the Flow

The first two specifications to consider relate to the air volume and air pressure as it is these that determine whether or not your compressor has the right amount and pressure of air to feed your downstream air powered tools.  Different air powered tools require different air outputs in order to work effectively and so finding this information out (usually from the tool operators manual) is key, especially if you are relying on the compressor to run multiple tools simultaneously.


  1. Air volume -The volume of air a compressor generates that is available to power a downstream application is known as the Free Air delivery (FAD) and this is the figure you need to know.  Air volume or the amount of FAD can be quoted in different ways with the most common being litres per minute (LPM), cubic feet per minute (CFM – when the flow is measured under variable conditions) or Standard cubic feet per minute (SCFM – when the flow rate is measured under standard pressure and temperature conditions).  These figures all relate essentially to the volume of air the compressor can provide and by using a simple conversion website you can help to ensure that you are comparing apples with apples.


  1. Air Pressure – These are usually quoted in bar (metric) or PSI (Pounds per square inch, which is imperial) and is basically the amount of force/ pressure of air the compressor can deliver. Different air powered tools require different air pressures to run effectively.   If the compressor is unable to deliver the correct pressure for a particular tool then the tool will either not operate correctly or if the pressure is too high it can cause damage.


Up and running

  1. A third area for attention and one that is often misunderstood is Duty cycle. This essentially is a measure of how long the compressor can run without needing a period of downtime to cool.  Figures are often quoted as percentages and this is important to watch out for as a compressor with a low duty cycle rating for example 25% or 50% will need periods of time to cool down each hour, which isn’t ideal if you need air to be produced continuously.   If continuous running is important for your application, then look out for a 100% duty compressor.


Hear yourself think

  1. It is easy to overlook the importance of noise levels in a search for a compressor, however a day of working in close proximity to a noisy machine can focus the mind!  Noise levels or sound intensity are usually quoted in dB or decibels.  Although the noise level of the compressor does not affect its performance, it can have a bearing on the productivity of nearby workers leading to poor concentration and in the most extreme cases, long term health issues.  In essence, the higher the compressor decibel rating, the greater the sound output.  Sound levels often range from 90dBA (equivalent to the sound of a food blender or lawn mower down to 60dBA which is the level of casual conversation.  When identifying the right compressor for your business it is worth thinking where it will ultimately be positioned and how close it will be to employees.


The list of factors to consider when making a compressor selection can be endless, but a focus on the key areas above will help to ease the decision-making process.  Additional factors for consideration depending on the application, include air quality requirements, portability, availability of a power source (electric or diesel) and the overall energy efficiency, however information on these are not always readily available online.


For help with choosing the right compressor for your business, contact the team at Vert who will be happy to advise, sales@vertrotors.com