There are many terms you'll come across including air compressor CFM, PSI, and BAR when investing in new equipment. In this guide, you'll better understand how CFM impacts what size equipment is most relevant for your needs, and its relationship to PSI.
Cubic feet per minute (CFM) measures flow rate. When discussing force, you'll encounter pounds per square inch (PSI), and BAR. This terminology is important regarding the pressure and speed needed to complete an application.
Flow or CFM is useful as it shows a compressor's ability to perform a task over a minute of operation. To put it into context, equipment like HVAC systems typically need 200 CFM. On the other hand, pneumatic power tools require 2 CFM to get a job done.
It's also worth mentioning that CFM directly correlates with an air compressor's horsepower. A 60-horsepower machine will generate approximately 150 CFM, while a 150-horsepower machine produces roughly 2000 CFM.
How much air compressor CFM is necessary?
All equipment using compressed air will list how much CFM is required for operations. If you're using compressed air for more than one machine, add up the total CFM for everything and multiply it by 1.5. This number will provide a good baseline for what you need. It's also important to note that this number is just a rough guide.
What is PSI?
As mentioned in the introduction, PSI is pounds per square inch. This quite literally means how many pounds of force is exerted per square inch / the amount of force that's applied to a given area.
Each pneumatically powered device has a stated range in which it properly functions. Too much pressure damages the equipment, while too little pressure won't get the job done. It's important to pay attention to ratings of both your air compressor and equipment operated.
How PSI relates to CFM
The relationship between pressure and volume in gasses can be explained by Boyle's Law, which states: P1 x V1 = P2 x V2. P1 is the initial pressure, V1 is the initial volume, and P2 and V2 are the final pressure and volume, respectively.
If you need to figure out the horsepower needed for a desired volume, enter your compressor's PSI and CFM, along with the desired CFM. The above equation will dictate how much horsepower is needed to make up the volume difference.
The risk of over and under pressurization
Don't overcompensate for pressure by unnecessarily increasing the PSI of your machine. Doing so results in increased energy costs. As an example, an industrial application might need 75 PSI, but the operator may turn up the machine to 100 or 125 PSI. Many times when this is done, it's because the person running the air compressor is uncertain about the amount of necessary pressure.
Pay attention to pressure regulators to lower pressure. Adding such demand is quite wasteful considering that up to 80% of an air compressor's operational costs relate to energy expenses. Generally, most operators run at 25 PSI more than necessary. This increase also impacts dryers and filtration systems.
On the flip side, running equipment without enough pressure for your application leads to issues like air leaks and other quality control concerns. These problems occur because of overworking your machine, past the point at which it was designed. Avoid costly problems associated with over and under pressurization.
Purchasing the right equipment
Throughout this guide, the importance of investing in the right equipment for your application is stressed. We've indicated how to generate a baseline assessment for your needs.
With fluctuating energy costs, you'll want the most efficient setup. In addition to air compressor size, it's worth looking for cost-saving features like energy recovery and variable speed drive (VSD).
If you need further insight, our team is happy to help. Feel free to contact us today. We offer air compressors with various pressure and flow ratings to meet your application.
