How to Increase CFM on an Air Compressor
Tips & Tricks

How to Increase CFM on an Air Compressor

We use air compressors for various home and industrial applications. However, different tools require different CFM ratings to operate. Therefore, you will need to increase your small compressor’s CFM output that cannot run tools that demand high power levels.

Typically, an air compressor comes with a specific CFM rating for a particular pressure. This rating is critical because it shows the air output for the proper performance of any unit. Therefore, the best way to boost your air compressor’s CFM is to buy another compressor and hook them up together or buy one with a higher CFM. However, if you are not in a position to, another option is reducing pressure. Read the article further to understand how to make the most out of your air compressor.

What Determines the CFM of an Air Compressor?

Determining the CFM of any units depends on its PSI range; additionally, this rating tends to vary depending on factors such as humidity, temperature, and atmospheric pressure. Most user manuals offer information on the CFM calculated at 90 psi and some at 40 psi. However, you may want to determine the CFM at 30 psi; this is how you do it:

  1. Determine the compressor’s capacity, which is usually labeled on the tank by the manufacturer in gallons. Divide this figure by 7.48. (7.48 is the number of gallons in one cubic foot). The result is the tank’s volume in cubic feet.
  • Empty your tank and then refill it. Time this process and record the starting and ending pressures in PSI. Find the difference between the two pressures. Convert the differential pressure to standard pressure(ATM) by dividing by 14.7ATM

P2-P1= P3

P3 / 14.7= P4

  • Multiply the result with the tank’s volume from step1.

P4 × V= V2

  • Divide the result by the time in seconds it took to fill up the tank.

V2 / Time = Y

  • Multiply the result by 60

Y × 60 =CFM

Another alternative is to use an airflow meter to calculate CFM, which reads the volume of flow and pressure from a unit. We use an airflow meter on single units and complete systems. For a more precise reading, we install the airflow meter near the receiver tank.

How to Improve CFM on Your Air Compressor

Keep in mind that the CFM of your compressor is constant; however, below are the three main ways you can improve the CFM of your compressor for more output:

Connect two air compressors.

Since a compressor cannot exceed its maximum CFM, you can buy another compressor and connect them to produce additional output. Follow the steps below on how to connect two compressors:

  • Connect the tank of both compressors with two different hoses.
  • Connect the two hoses with a third hose.
  • The third hose should have three holes; two for the input and one for output.
  • Connect your air tool to the output.

It’s essential to ensure the hoses have check valves that prevent air from flowing back to the compressor. Also, ensure the combined CFM is adequate for your air tools; therefore, you can always get a well-sized compressor.

However, there are several drawbacks to this process;

  • It will take much longer to fill up the tanks with air.
  • The two units are likely to overheat.
  • The set-up may need more maintenance work to perform efficiently.

Reduce the pressure of your air compressor.

A cheaper and simpler alternative is reducing your compressor’s PSI. But first, you need to understand the relationship between pressure and CFM mathematically. We know that CFM= Volume/ Time, where, Volume/ Time represents pressure, meaning you have to reduce the pressure to increase the CFM.

You achieve this by gradually setting the regulator down to the lowest point. Reducing the pressure will make sure the compressor motor runs for a longer time (might not be good for lifespan), making the compressed air density higher. For instance, you’re working an air tool at 150 psi; it means the tool demands more air pressure to perform. Lowering the pressure to 90 psi will give the compressor time to keep the compressor’s pressure for longer. However, the CFM of your compressor remains the same.

A positive side to this method is that it will improve your compressor’s lifespan, and it also gives the compressor time to fill up while it’s used concurrently with the tool. However, it is not the most reliable method if you need double or triple the CFM to work your more powerful air tools.

Purchase a more powerful compressor

The best method of increasing your CFM to support all your demanding air tools is to buy a compressor with a higher power. If you use your air compressor with several tools simultaneously or continuously, purchase one with the CFM equal to the highest power you use. Though a pricey option, this method helps you cut down on maintenance costs associated with overworking your compressor beyond its maximum to run powerful air tools.

How big of a compressor do I need to run air tools.

Different tools require different CFM ratings to operate. For example, a general wrench needs about 5 CFM to run correctly, whereas a framing nailer requires about 2.2 CFM. Below is a table with standard tools and their corresponding average CFM rating.

TOOLPressure in CFM
Angle disc grinder5-8
Brad nailer0.3
Cut-off tool4-10
Drill3-6
Dual sander11-13
Grease gun4
Hammer3-11
Hydraulic Riveter4
Impact gun6.8
Impact Wrench – 1/2″4-5
Impact Wrench – 3/8″3
Impact Wrench (1″)10
Mini die grinder4-6
Needle scaler8-16
Orbital sander6-9
Paint spray gun4-8
Rotational sander8-12.5
Shears8-16
Speed saw5
Staple gun2
Tire inflator2

How to get the best out of your air compressor capabilities

Following these tips below will help you maximize your compressor capabilities.

  1. Create and sustain a regular maintenance schedule for your compressor. A well-maintained compressor will always perform at its maximum and also serve you longer. Regular maintenance should detect leakages, oil changes, lubrication needs, and see worn-out parts for replacement and repairs.
  2. Drain the moisture in your compressor’s tank periodically, mainly if you use your compressor daily or live in a humid region. The accumulation will corrode your tank and overwork your compressor over time.
  3. Avoid overloading the compressor with too many tools. Your compressor will work more efficiently when you use one tool and reduce maintenance costs caused by overheating.
  4. Ensure your air compressor’s proper lubrication and always use the one suggested by the manufacturer as the lubrication formulation should meet the compressor’s specific needs, such as preventing rust.
  5. Use hoses with a short length with your air compressor because the longer the air has to travel, the more the pressure drop is.
  6. Use thicker hoses of about 3/8 inches in diameter.

What is the best CFM rating for a home garage air compressor?

For a home garage use, an air compressor with 9-14 CFM for 90-100 psi is a good rating. However, compressors come in different types and have different CFM to suit their applications, meaning your compressor needs to be as powerful as the tools you use.

What is the difference between PSI and CFM?

The difference is PSI( Pounds per Square) measures pressure level while CFM(Cubic Feet per Minute) measures an air compressor’s volume. The pressure gives the compressed air its power.

If an air compressor is rated to produce 90 psi; therefore, we exert 90 pounds of pressure per square inch. CFM is the quantity of air a compressor can move in a minute. An air compressor with 30 CFM output means that 30 cubic feet of air are flowing per minute.

Both terms are not equivalent, but they indicate compressor performance.

Buying a powerful air compressor is the only way to avoid the stresses of increasing your air compressor. It would help if you always matched your compressor’s power with your tools accordingly. However, the above tips will help when increasing the CFM of your air compressor.

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