PSI? CFM? Horsepower? Choosing the Right Compressor

Horsepower? PSI? CFM? There is a lot to consider when purchasing a new air compressor. It is important to understand what you actually need and how to find out.

Choosing an air compressor solely based on horsepower could negatively impact overall operating expenses.

One of your primary concerns when choosing an air compressor should be “how can I get the most amount of compressed air for the lowest overall cost?” Many consumers only consider the initial investment in the machine – not realizing they will likely spend more in electricity the first year to run the machine than the purchasing price.

So, the first step in choosing a compressor is determining the Cubic Feet per Minute or CFM demand your plant requires. CFM describes the volume flow rate of compressed air. Improperly sizing your compressor can cost thousands of dollars in wasted electricity.

It is important to know in this situation, that more horsepower is not always better. It goes without saying that a higher HP machine uses more electricity than a smaller one. For two air compressors with the same horsepower the CFM output could vary by as much as 25% between companies and models.

In order to make an informed decision, it is critical to understand that all compressors are not designed equally and that you may be able to use a smaller HP, more efficient compressor that produces the same amount of CFM, allowing you to keep profit in your pocket.

We have already stated that not all compressors are made equally, so how is a consumer to know CFM ratings, HP ratings and total package energy usage? Well, a group of compressor manufacturers realized this dilemma and created a group called CAGI (the Compressed Air and Gas Institute). Each compressed air manufacturer agreed to have their compressors independently tested and verified. Once verified, certified data sheets, similar to a car’s window sticker when car shopping, are published publicly on each company’s website with key information to make your decision easier.

On each CAGI sheet, the amount of CFM the compressor produces at a given pressure, the maximum PSI (Pounds per Square Inch) that can be produced, and the efficiency of the compressor in KW/100Cfm (similar to an automobile’s miles per gallon) rating can be found.

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Who we are and how Ash Air can help your business!

Ash Air has been around in New Zealand since 1979, and we’ve grown into a nationwide company with international support and a reputation for quality and reliability.We look after all things compressed air for your business!

  • Reciprocating, Screw, air compressors
  • Vacuum pumps
  • Nitrogen
  • An extensive line of air treatment components

Ash Air's range of Chicago Pneumatic, Alup, Pneumatech, and Quincy compressors are used extensively around the world in industries ranging from oil and gas to food, automotive and farming, and we bring you these world class compressors here in the land of the long white cloud.Our technicians are compressed air equipment experts and are dedicated to addressing customer needs. Supported by a 13 locations nationwide, Ash Air offers one of the widest selections of compressed air equipment and parts available today in New Zealand.

Reliability and Efficiency

With Ash Air compressors, you can count on reliability and high performance for even the most demanding applications. We focus our efforts on the following:

  • Increasing uptime
  • Reducing unexpected repairs
  • Reducing energy consumption
  • Improving the cleanliness of compressed air


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