C02 is often used as a shield gas....it simply does not work well as a plasma gas....I believe that it causes difficulty with arc starting due to it's ionization properties. Typical plasma gas combinations in order of their popularity: 1. Air (because low cost air plasma systems are designed for use with this gas....and users think that air is free) 2. Oxygen (by far the best way....and usually the least expensive way to cut steel due to it's ability to cut faster, cleaner...resulting in more parts and less secondary grinding...in recent years technology with high end systems such as high definition plasma...has further improved consumable life, cut quality and speed for this process gas) 3. Nitrogen (usually used with a shield gas of C02....or water, or water injection for best cut quality on stainless steel) 4. Argon/hydrogen in a 35% hydrogen mix (used for excellent cut quality on stainless and aluminum thicker than 3/8") 5. Nitrogen/Hydrogen in a 5% hydrogen mix (used with high definition class cutting of thin stainless for a metalurgically superior cut edge suitable for weldability).
Most air plasma torches are only compatible with either air or nitrogen....it is dangerous to use other gases if the system is not designed for their use. Most air plasma torches also are a single gas torch.....so a shield gas cannot be utilized as in high end industrial torches.
Apollo 1....as a kid I was infatuated with the space program....when Grissom, Chaffee and White were killed on the launch pad (oxygen supported fire) I was devastated...
Jim  |