Nitrogen Use in a Plasma Cutter

Hey all,

Ive read that for cutting stainless Nitrogen is preferable to shop air for a plasma cutter. Supposed to be much better at eliminating the built up carbides, IIRC. Does anyone know if theres anything special that one must have/do before using nitrogen in a plasma cutter? Special machine?

Obvious a suitable regulator would be necessary. Would argon work as well?

NK

Most plasma torch tips and electrodes are designed to be used either with shop air or nitrogen. Think of it like shielding gas when mig or tig welding- you can change your gas mix without having to change to a different welding machine.
The key here is inert gas, the same as when tig welding stainless. Argon might work, but it is pretty pricey for this- I just filled 2 tanks of argon, 250cubic footers- 180 bucks for the pair. Nitrogen is used because it is the cheapest commonly available inert gas. But there could also be electrical conductivity or plasma generation reasons why nitrogen is chosen- not sure about that.

It would be a quick experiement, though- just grab a tank and flowmeter from a tig welder, its the same pipe threads as on the back of most plasma cutters, and try it out. I would guess that you might have to run at a higher rate than tig welding, however.
My plasma cutter likes 50 psi, but I dont know the cfm consumption of the plasma cutter, which is what argon flowmeters are rated at, but I would guess its more gas flow than you set your tig welder at, so gas consumption would be higher

Ries, thanks for the info,

I was just curious about nitrogen because it has the tendancy to form nitrides instead of carbides at the joint. I guess in a cutting process this is minimal. Ill try it as soon as I have time to fiddle with that!

NK

A small point: once you've got your nitrogen tank and regulator, you can recharge the A/B/C fire extinguishers via some country boy plumbing. My gas guy said it's simple to do.

Just a minor point. Argon is an inert gas. Nitrogen is not. At high temperatures it forms all sorts of compounds.

I looked at this a while back, would have used a LOT of nitrogen in a small shop. Enough nitrogen to have some issues with how much Oxygen was left in the room....

damonfg,

I plan on only having this rigged up for stainless (10% of what we do, maybe). Also, our building is a fairly large hangar. We should be ok...

NK

Not saying you will die trying - just check the math to be sure you will be safe.

My 60A plasma cutter keeps my 4kW compressor busy on about a 50% duty cycle. That's maybe 15 cu. ft/min. Guesswork only, but I reckon you'll empty a large size nitrogen bottle in well under an hour. You may run the risk of icing up the regulator.

Nick.

My understanding is that air is fine to run in a plasma setup as long as it is SUPER dry. Run a good desiccant system (maybe a multi-stage unit) and I'd think your plasma unit would run fine on air.