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Demystifying Common Air Compressor Myths

According to the Merriam-Webster dictionary, a myth is defined as “an idea or story that is believed by many people but that is not true.” A myth’s origin is usually unknown, but is almost always the product of a lack of factual information. In the tool and equipment world, these misconceptions can lead to improper operation or regrettable purchasing decisions.

We encounter a lot of these misunderstandings when working with customers to find the right air compressor for their application. We get it. With all the industry jargon, technical terms and units of measurement that get thrown around, it’s easy to confuse the details.


When preparing for this blog post, I asked our sales and service staff to think about their interactions with customers and come up with a list of recurring misconceptions that they have helped to clarify. Within minutes I had more than I could possibly fit into one post, so I narrowed it down to the following five air compressor myths:

1. Focus on displaced CFM.

Displaced CFM is calculated by multiplying the pump’s bore and stroke by its RPM. The result might look good in marketing collateral, but it won’t give you an accurate idea of how much air you’re actually getting out of your air compressor. Delivered CFM (or free air delivery) is what really matters, as it factors in the regulated pressure setting (PSI). It’s a measure of the actual air you have at your disposal.

2. It’s all about tank size.

Tank size is an important factor, but it won’t make up for an improperly sized pump. If the pump doesn’t deliver enough CFM, the reserve air will get used up very quickly and you’ll have to stop what you’re doing and wait while the tank refills.

Determine the amount of delivered CFM you need and then think about how your pneumatic tools operate. If they operate in quick bursts like nailers and staplers, you’ll be fine with a tank that holds 10 gallons or less. If they run for longer stretches, like grinders, sanders, or spray equipment, go with a larger tank. We offer models ranging from 30 to 120 gallons.

3. Single-phase vs. single-stage. Same thing, right?

The terms single-phase and single-stage have a similar ring to them, and, for someone who doesn’t have a lot of air compressor experience, it’s easy to confuse them. When buying a new air compressor, however, it’s important to understand the difference.

Single-phase refers to the power supply in most homes and small businesses throughout the U.S. The alternative is three-phase power, which is commonly found in industrial and manufacturing settings.

Single-stage refers to the number of times air is compressed in a reciprocating pump. Single-stage pumps compress air one time. The alternative is a two-stage pump, which compresses the air twice. In general, two-stage pumps produce more CFM and operate more efficiently.

4. Overvaluing PSI.

Some people focus solely on the maximum PSI rating of an air compressor. They know the pressure at which their tools operate and assume that, as long as the air compressor can meet those requirements, they’re good to go. The problem with this scenario is that a key factor is being overlooked – flow. You can’t have pressure (PSI) without flow (delivered CFM). As your pressure increases, the flow will decrease.

All pneumatic tools use up a certain amount of CFM while in use. If your air compressor doesn’t produce enough air for a particular tool, that tool won’t function properly, regardless of the pressure setting.

5. Hung up on horsepower.

In a past blog post, one of our distributors compared sizing an air compressor based on horsepower to asking your pharmacist for any medicine available in 250mg pills. Clearly that’s not a very effective way of getting the treatment you need.

Now imagine walking into your local construction supply store and asking for a 2 horsepower air compressor. Not all 2 horsepower air compressors are created equal, so you’d likely receive a flurry of questions like, “Portable or stationary? Direct drive or belt drive? How many and what types of tools are you using?

In the end, you may or may not end up with a 2 horsepower compressor.


These are just a few of the misunderstandings that we encounter every day. A simple line of questioning is usually enough to clear things up. The best thing you can do is to be prepared with information. Know what tools you’ll be using. Know their CFM requirements. Know what type of power is available at the facility or job site. Knowing the answers to these questions will help ensure that you end up with the right air compressor for the job.