What size air compressor do I need for air tools?

When a friend of mine was installing his garage he had to ask himself the following question: What size air compressor do I need for air tools? He already had some of the best air tools but I still needed the element that would power that equipment: the air compressor.

He didn’t know which to choose; he had been told to only buy the biggest one his budget could get. But making a decision based only on the money available did not seem to be the best idea, so I helped him to research and we realized that there was a whole set of important factors to analyze and several questions to answer to make the right choice.

First of all, in what kind of projects are you going to work?

Air compressors are devices which you can give a very large variety of uses, so you should be clear if you will perform domestic works, occasional maintenance, construction projects or major automotive repairs. The type of tools you are going to use and the air consumption of each of them will ultimately determine the capacity of the necessary compressor.

What size air compressor do i need for air tools

What size air compressor do i need for air tools

What type of pneumatic tools will I use and what are your requirements? 

There are tools like sandblasters that require a constant supply of air. In this case, you will

Have to buy equipment with a bigger tank and enough air􀃓flow, in the other hand, a tool like a brad nailer could work with a small portable compressor without a tank. For an automotive repairing shop surely you will need a piston compressor with tank. If you choose the wrong size compressor and it is not enough big you’ll have to be filling the tank frequently; which will decrease the productivity of your work.

Known automotive air tools

Known automotive air tools

How much air pressure do you need for air tools?

There are several key technical aspects that must be considered to select a compressor:

  1. Necessary air pressure: it is the pressure at which the compressor is required to work and is expressed mostly in units such as PSI (Pound Per Square Inch), or BAR (1 BAR = 14.5 PSI).
  2. Air flow: is the volume of air that the machine can compress per unit of time. It is measured in CFM (Cubic Feet per Minute), in l / min (liters per minute) or in m3 / min.
  3. Power: It is the capacity of work that has the compressor and is measured in HP (Horse Power), in CV (Steam Horses), or even in KW (Kilowatts).

Each compressor model can provide a certain flow and pressure at a different power, therefore, knowing the needs of air flow and pressure you can set the power that the compressor should have. As for the pressure, most of the tools work at a standard value of 90 PSI, although there are some that require 100 PSI or even 120 PSI. The flow can be obtained by adding the individual flow required for each of the tools that will be connected to the system.

These values can be obtained by reading the technical specifications plates that each device must have with them or their respective user manuals. As an example, let’s assume that the sum of the CFM required by all our tools totals about 18 CFM. To this value, we must apply a factor that is given by the duty cycle of the compressor. It means how long the unit will be running during working hours.

For example, if we estimate that 60% of the working time the compressor will be supplying air to the air tools and we do the math: 0.6 x 18 CFM = 10,8 CFM we obtain the amount of air flow needed.

Besides, it is recommended that you consider an additional clearance that allows you to cover the variations that exist in the total value of CFM required, especially when there are several hoses and pneumatic tools connected and working simultaneously. It will also allow you to add new tools to the system in the future. Usually, a clearance of 30% to 50% additional is added to the calculated CFM.

Therefore, if we add a 30% to the calculations of our example, we will have a requirement of 14 CFM at 90 PSI, with these values we can determine the power (HP) that our compressor should have. It will also be very important to know the voltage and the current intensity supplied by the electricity network of the place where the compressor will be located.

You should also consider other elements such as the capacity of the compressor tank. The capacity of the tank will depend on the time in which the pneumatic tools will be operative until the motor of the compressor must be turned on again to compress more air.

Some pneumatic tools need a continuous flow of air. This merit a larger tank than those that work in short cycles. The longer the time between turning the compressor motor on and off, the longer its life will be.

What is the best air compressors for car restoration air tools?

One of the best air compressors for car restoration air tools you can find in the market is Powermate Vx PLA4708065 80-Gallon Electric Air Compressor, which fits the requirements of our example and features a 240-volt the motor with 4.7 HP and offers 14 CFM at 90 PSI and has an 80-gallon capacity tank.

  

Last but not least, you should consider factors such as a correct location for the compressor in which it can have sufficient ventilation and be preserved from the elements of the weather, the location of the tools with respect to the compressor in a way that minimizes falls of pressure in the lines. Don’t forget that there may be regulations imposed by local authorities regarding noise levels and that some models of compressors may generate fewer noise levels than others, especially if they are lubricated by oil.

Finally, you already know how to calculate what size of air compressor you need to remove lug nuts, to inflate tires, to run an impact wrench or any other task you want to get done, so you can go to the store and buy the best air compressor available to elevate the productivity of your work to the maximum level.

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