[magma-joe]

Anybody ever use nitrogen for cutting gas on a conventional plasma? I have a Hypertherm 1250 on a Dynatorch 5 x 10 table and cut some aluminum parts. When using shop air the edge of the cut is oxidized which requires alot of grinding and prep work before I can Tig weld the joint. I know using nitrogen could be costly however I only cut a couple of these parts a month and could easily add the cost into the job. Anybody ever try it? Maybe Jim Colt could chime in? Here is some food for thought, http://www.praxair.com/praxair.nsf/AllContent/641292709A218CFC85256E7C006B9A69/$File/P-8236.pdf
http://www.centricut.com/New_Lessons/lessons_9.html

[jimcolt]

When cutting with nitrogen plasma on aluminum and stainless you may see slightly less oxidation....(although some will still be present from ambient air that surrounds the cut) however expect a higher chance of dross formation. If you have the ability to submerge these materials 1/2" or more under water when cutting....the oxidation will likely be eliminated as the water shields the hot cut face from oxygen that is present in ambient air.

High end plasma systems such as Hypertherm HyPerformance plasma use a separate shield and plasma gas.....you can use F5 (5% hydrogen,95% nitrogen) as the plasma gas and nitrogen as the shield.....effectively eliminating oxidation and dross on the cut edge.

On most air plasma systems....only use either air or nitrogen as other gases can cause torch failure or combustion that could cause injury.

Jim colt