How to Increase CFM on An Air Compressor?

Sometimes you need a little higher CFM than the air compressor you have now can deliver to your tools. Right? Yes, it often happens. For example, your compressor has a flow rate of 5.7 CFM at 70 PSI but you want to operate a paint sprayer requiring 7 CFM rating. Then you are looking for an effective way of increasing CFM of your current air compressor. Don’t panic. I understand your problem and it’s possible to make your compressor higher CFM one. Here are the possible solutions for your problem.

To increase the CFM of your air compressor, you can apply either of following two techniques.

Method One: Increase CFM by decreasing PSI

Before applying this technique, you need to know the relation between pressure and CFM mathematically. We know that power = volume/Time, where volume/time indicates pressure here. That means you need to lower down the pressure if you want to increase the CFM.

Every air tool has a lowest limit of pressure to work. By setting the dial lower down to that lowest point, it’s possible to maximize the CFM. Let me tell you how it happens.

Setting the regulator down keeps slowing the air flow in the tank down and allows the compressor to to keep filling the tank for a long time. This is because the higher the pressure, the higher flow rate the air tool demands, and the harder it is for the compressor to fulfill the the demand of air tool. When the pressure is kept at the possible lowest point, the compressor can keep up with this amount of pressure.

Let’s consider a situation for a clear explanation. You have an air tool working at 150 PSI, and you are going to lower down it to 90 PSI. When the air tool operates at 150 PSI, it demands more air compared to 90 PSI. As a result the pressure in the tank drops very quickly and the compressor cannot pump air into the tank as much as the tool requires.

On the other hand, when you lower down the pressure to 90 PSI from 150 PSI, there is already enough pressure in the tank and it will take long time for the pressure to drop. This gives more time for the compressor to keep the air pressure up in the tank. Yes, this is an effective way to solve your problem. But in reality, CFM of your compressor is still same however you set the regulator.

Method Two: Combining two compressors for higher CFM

However, if you need a CFM higher than your compressor can provide you maximum, the former method may not work. In this case, connecting two small compressors will deliver the desired flow rating. For an example, if you have two small compressors having 4 CFM each, and your air tool requires 8 CFM which is beyond the maximum capacity for one then it’s possible to obtain 8 CFM by connecting two together.

To do so, all you need is three hoses, two of which are used for connecting both compressors and the third one is for connecting that two. The third one should have three holes, two for inputs and another for output. To complete the process, you need to connect the output with your air tool.

You are done but here two important factors you need to consider while following this strategy.

Two things to consider when you need  to increase CFM of compressor 

Check Valves

There must be installed check valves in the line connecting from each compressor so that air cannot flow back to the compressor but can flow away from the compressor.

Pressure Adjustment

Both compressors should have similar amount of kick in and kick out pressure. This will ensure the same amount of work done by each one to meet the air demand of the air tool. If there is too much difference between two pressure switches of both compressors, one compressor may have to do almost all the works. This will cause much more frequent stops and starts of that one. So it’s crucial to adjust the pressure of both compressors.

Furthermore, before connecting two compressors, you must ensure if the increased CFM is sufficient for your air tools. If still not enough, it’s better to buy a larger one.

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Olivia Archer
 

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