Nearly all plasma cutting systems fall under two categories: Conventional and Precision plasma systems. Conventional Plasma Systems – Typically use shop air as the plasma gas, and the shape of the arc is determined by the nozzle on the torch.
Nitrogen is often used for higher current plasma systems and for cutting materials up to 3 inches thick. It produces excellent quality cuts on most materials. Oxygen is used when the highest quality mechanized cuts are desired on carbon steel up to 1 -1/4 inch thick. The cut face is smooth, and dross is easy to remove.