How Big Of An Air Compressor Do I Need For A Plasma Cutter?

When choosing an air compressor to use with your plasma cutter you need to consider the compressor’s CFM rating (cubic feet per minute) and the amount of CFM your plasma cutter consumes. Any compressor can work for small short cuts, but in order to keep your long cuts uninterrupted by a lack of air pressure you need to have a compressor big enough to keep up with your machine’s air consumption.

The general rule for buying a compressor is the bigger the better. Manufactures recommend you buy a compressor that is rated for about 1.5 times the CFM (cubic feet per minute) of your plasma cutter. For example, the Hypertherm Powermax30 XP requires 4 CFM at 80 PSI. Ideally you would want a compressor rated around 6 CFM to use your machine without the chance of having a low pressure interruption during heavy usage.

Note: Manufactures usually rate their compressors CFM at 90PSI as well as the max PSI the compressor can produce. This is the standard across multiple brands. Most CFM ratings are inflated (no pun intended) by manufactures. So a machine that says it produces 5 CFM is realistically probably around 4 CFM.

With all of this said, you can get away with using a smaller compressor as long as you are not making super long cuts with your plasma cutter (longer than a minute). A majority of users are only making small to medium sized cuts, so they can use a compressor that is under the recommended manufacture rating. A small 30 gallon compressor rated at 5 CFM will work without any problems for most users.

Keep in mind, if you use a smaller compressor and start to make long cuts your compressor will not be able to keep up. This will cause your machine to throw a low pressure light and stop working temporarily while the compressor takes time to build more air.

Plasma cutters operate on a wide range of different PSI settings and you must refer to your machines manual to find the correct setting for your machine. In general, larger machines require a higher PSI and smaller machines require a lower PSI. For example take a look at the different machines below offered by Hypertherm:

• Hypertherm Powermax30 XP (30 amp): Runs at 80 PSI using 4 standard cubic feet of air per minute.
• Hypertherm Powermax45 XP (45 amp): Runs at 90 PSI using 6.7 standard cubic feet of air per minute.
• Hyperterm Powermax65 (65 amp): Runs at 85 PSI using 6.7 standard cubic feet of air per minute.

Some plasma cutters have a built in air regulator in the machine that will choke the air down to the correct pressure needed. If your machine does not have this, you can purchase an external air regulator to mount on your plasma cutter or your compressor. This will allow you to adjust the PSI of your air supply line.

Air filters will remove particulates and moisture from the air sent to your plasma cutter. This will help increase cut quality and torch consumable life. You can check out our article about air dryers for plasma cutters here.