How much air pressure do I need for a plasma cutter?

Typical plasma cutting machine air pressure ranges from 4-8 SCFM with a pressure of 90-120 PSI. this article details the air pressure requirements for plasma cutting machines and some of the conditions necessary to keep the system stable.

 

What is the air pressure for a plasma cutter?

A plasma cutter is really the best tool for your shop. It helps in cutting different metals of various shapes quickly. The basic requirement of a plasma cutter is compressed air. The plasma cutter air pressure gauge provides you with an accurate reading to set the air pressure. Plasma cutters are very similar to electric welding. 

A superheated arc heats the compressed air of the system to a point where it transforms into plasma. Usually, a starting arc is required to create the plasma. To be precise, the air pressure required for a plasma cutter is about 4-8 SCFM at 90-120 PSI. This plasma cutter air pressure is a generalization for cutting steel between 3/8" and 7/8" thick. 

 

Some other requirements of a plasma cutter

A central unit provides compressed air to the system. In addition to the central unit, the plasma cutter requires two gear pieces, an air drying/filtration system and an air compressor. Moisture may prevent the proper operation of the instrument. The air compressor provides the necessary air for the plasma cutter. The drying/filtering system ensures that the plasma cutter stays dry.

 

Impact of air quality on plasma cutting

Air quality is critical to plasma cutting. If any type of oil or water particles are present in the compressed air, they can affect the quality of the cut. The system's consumables may also burn quickly. The system should also be protected from dust ingress. A plasma system that is susceptible to dust can be damaged quickly, and wearable parts such as electrodes can wear out quickly. 

 

How to match the air compressor to the plasma cutter

Do not pair a plasma cutter that requires 4 CFM with a compressor that produces 4 SCFM. The compressor is unlikely to keep up. There are several reasons for this.

One is that this is the maximum rating of the compressor. That's like saying your car has a top speed of 160 MPH and then expecting it to maintain that speed on a long road trip across the country. That's not a good idea. You will definitely burn out your compressor. Good compressors aren't cheap either.

Another problem is that the output rating is calibrated to a specific altitude, temperature and humidity level. You will notice that the CFM rating has an S in front of it. this means standard cubic feet per minute. This is calibrated to 68ºF, 0% humidity and sea level. If either of these numbers goes up, your compressor output will go down.

If you do not want to spec your compressor for ambient conditions, simply add a 50% fudge factor. For example, if your plasma cutter requires 4 CFM at 100 PSI, you should have a compressor rated at least 6 CFM.