General Specification Terms of an Air Compressor: CFM, Tank Size, and Power

An air compressor is a big and a very practical investment for a business or for a home. It is necessary that before you buy one you understand the basics about the equipment because you want to be absolutely sure you buy the right one. You need to make a comprehensive list of all the tools that you will be operating with the help of the compressor. With the list you can easily work out the cubic feet compressed air consumption frequency (CFM) and the volume of compressed air will pull from the storage tank. Do not worry if this sounds very technical it will be revealed to you in this article.

A compressor is like a mechanical lung which pulls in large amounts of air, stores it in the lung capillaries for a while and the body uses the energy as and when required. Also imagine how one inhales a large quantity of air to blow a balloon. Being familiar with the technological terms such as given below will help you immensely to have a basic understanding while choosing an air compressor:

Cubic Feet per Minute Consumption (CFM)

Cubic feet per minute is a unit of volume capacity, it measures the amount of gas independent of its density (in the case of compressors, the compressed air) that is required to power a tool and is also referred to as inlet cubic feet per minute (ICFM). The standard CFM consumption of air tools varies from tool to tool. If you plan to operate various tools at a given time, then it is necessary that you calculate the cumulative CFM consumption. The CFM for each tool is generally known and is specified on the tool more often than not. Add the cumulative CFM for the equipment that you will be operating simultaneously to arrive at the lowest CFM rate and add a buffer of additional thirty to fifty percent.

For example the CFM of tool 1 is 2 units and that of tool 2 is 1 unit then you require a total of 3 CFM and add to it a buffer of 50% and your air compressor requirement is 4.5 CFM.

Tank Size

Tank size refers to the air pressure storage tank which occupies all the potential energy in the form of air and supplies it as and when required. Different types of compressors come with a different sizes of storage tanks but the principle “bigger the better” applies. Think of all the tools and the amount of time each tool will be operated while selecting the tank size. For electrically powered machine you might go for a smaller tank as you can charge the machine whenever required however when it comes to mobile air compressors operated on petrol or diesel a big tank is a must have.


Electrically operated compressors can be generally powered by a typical 110-120 V power supply switch. However air compressors with a more than 2 Horsepower motor unit will require a 220-240 V power supply. While working in closed spaces electrically powered compressors are the best deal.

Petrol and diesel operated air compressors are completely independent of electric energy and are therefore mobile in the real sense. But these produce harmful gases and are not ideal to be used in closed spaces. However natural gas compressors can come to your rescue in case you do not want an electrical compressor. You have to understand how much per liter of gas CFM can be achieved to power your tools. This data will mostly be available with each independent type of machine and CFM requirements.

To conclude, these are the basics of an air compressor that you must understand in order to choose the best suited machine for your needs. When these factors are actively considered it is possible to reduce further expenditure on the air compressor in the form of repairs and maintenance as your machine won’t be over-or-under-utilized and you would not have to consider further investment in other machines if you get these factors right along with the basic calculations of CFM required by the tools that you intend to operate.

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