What You Need to Know About CFM and Air Compressors

There are three things to consider when choosing an air compressor: size, power, and discharge pressure. Size refers to the air tank. Power is the horsepower of the motor. The discharge pressure is the pressure of air delivered.

The horsepower rating can easily draw attention, but HP is not always indicative of the true power of the compressor. Air delivery rate expressed in cubic feet per minute (CFM) and discharge pressure expressed in pounds per square inch (PSI) are more accurate values in demonstrating the capability of an air compressor.

Why is CFM important when Renting Air Compressors?

True air compressor power is based on two values: the volume of air delivered at a certain pressure level. These two ratings are inversely proportional – when one goes up, the other goes down.

The rate at which compressed air is delivered (CFM) works in conjunction with the rate of discharge pressure (PSI). If the CFM goes up, then the PSI may go down.

CFM may vary depending on air temperature, atmospheric pressure, and humidity levels. If you see a standard cubic foot per minute (SCFM) rating on the label, it means the CFM rating is measured at sea level, with 35% relative humidity, and at 68 degrees Fahrenheit. Each SCFM rating is given for a specific PSI value.

Why do you need an Air Compressor?

When renting an air compressor, determine what you need it for before picking a unit.

• Are you looking for an air compressor for a hobby or industrial use?
• How often do you need to use the air compressor?
• Do you need a mobile on-the-go machine or stationary equipment?
• What type of tools will you be using with the air compressor?
• How many people will be sharing the air compressor?

Each air compressor has a maximum CFM output. Check the tool that you will be using and make sure the CFM output of the air compressor is more than what is required by each tool to operate efficiently.

For example, pneumatic tools typically require around 5 CFM. Impact wrenches that are 1/2-inch in size will need about 5 CFM at 90 PSI. In both instances, choose an air compressor with above 5 CFM output. If you have two technicians operating two wrenches simultaneously, then the air Compressors rating should be a minimum of 10 CFM.

These types of tools usually run in 20- to 30-second intervals while heavy machines such as sanders and grinders operate for 20 to 30 minutes nonstop. For this type of prolonged usage, you need a higher CFM.

Need more information about the air compressor you need for your project? We offer a wide selection of air compressors for any job size – just look for the SCFM rating and PSI number when you order a rental. Contact us for more inquiries.