Using gas other than air on a plasma..

[hotponyshoes]

Hi,
I have heard there are benifits to be gained from using gas other thasn air with a plasma cutter.
I belive using nitrogen as the cutting gas gives a cleaner cut, is this correct and if so is it enough emprovement to be worth the extra cost?

If so, how do you do it?

I opened up my plasma cutter and the air connection ion the back of the machine goes into a 't' piece. this then gives 2 feeds to the machine, i presume one is for cutting and one is for the shield.

If i remove this 't' I take it i could run 2 fittings to the rear of the machine, feed the cutting side with nitrogen and use argon on the shield side?

How do you work out what pressure to feed the gas at?
As it stands the machine has a regulator on the back but i think this is used more as a water trap. I put a 10bar air supply on it and it doesnt seem to make any diffrence if you adjust the regulator. If you turn it down too far the 'low air' light comes on and it wont fire up but thats it.

Is it worth trying?
I was thinking i could make up a simple 'y' piece from air hose to run the machine on compressed air when I didnt want to use other gas.
Thanks.

[massajamesb]

All you need is a nitrogen bottle, and a regulator that will allow for up to 75-80 psi output. Don't worry about tapping into the lines on the plasma, leave those alone, just hook up the bottle like you normally would shop air.

Nitrogen has no moisture or oils in it, so your tips will supposedly last longer. From what I understand, nitrogen is generally used mainly for High-definition plasmas, and really not needed on smaller mainstream plasma cutters.

I don't know how much you would pay for a bottle, but I pay about 25 bucks for a 220 bottle here. It might be worth it to rent a bottle and try. If it doesn't make a dramatic improvement, take the bottle and regulator back.

[ImanCarrot]

Doesn't nitrogen kill you in enclosed spaces without any warning due to lack of oxygen getting into your lungs? like if there's a leak or sometheing? I know we used to work in a research lab with huge lasers purged with Nitrogen and there were warning monitors and breathing aparatus everywhere.

Or are you only talking about a little bit of N2?

I know they use it to kill poultry cos it's more humane than CO2 cos they can't feel they're suffocating.. you can feel suffocation from CO2, but not N2.

Sorry if I am barking up the wrong tree here...

[massajamesb]

Hmmm. That would explain my dizziness......

Just kidding. I have a 2000+ square foot shop, and when I tried using it in my old Hypertherm 600, I never noticed any breathing problems,etc.
I have asthma, and it can be triggered by almost anything. I figure if it was going to kill me, it would have.

I guess if you wanted to go burn parts in your closet with nitrogen, that would be detrimental to your health. But in a large, open shop with ventilation, I can't see a problem.

NOTE: if you use nitrogen and die, you hereby agree not to sue me for merely tossing in my two cents.

[Torchhead]

Cutting steel with dry air will yield results close to using another gas. Spend you money on putting in a series of dryers or a Ref dryer unit. You will run through a bottle or two of NO2 a day at 70-80 PSI and at 25.00/bottle it would quickly become a primary cost of cutting.

Setting up a constant level water tank with the material sitting on the surface of the water will do more for cut quality than using inert gases for cutting. The HD torches use a dual gas mix but you are talking about a piece of equipment that costs 10X the cost of a regular plasma.

None of it will do you much good without a good Torch Height Controller and a good torch.

Tom Caudle
www.CandCNC.com

[ImanCarrot]

NOTE: if you use nitrogen and die, you hereby agree not to sue me for merely tossing in my two cents.

rofl

Nitrogen leaks are truly deadly in enclosed spaces.. heavier than air and the human senses can't detect it.. unlike CO2 (where you feel breathless).. it's even been proposed as a more humane form of capital punishment it's that effective.. sleepy death

You should be ok in a well ventilated area I spose... but the amount of results I got on google from "Nitrogen asphixiation" and "nitrogen welding hazard" were enormous... here's one:

http://en.wikipedia.org/wiki/Nitrogen_asphyxiation

Here's one about the other gases produced:

http://www.twi.co.uk/j32k/protected/...faq_ozone.html

As an aside.. some of the chaps working INSIDE our N2 purged laser system wore full "frogger" suits with a big long hose to supply air... I wondered what the axes all along the corridor were for... apparently if an evacuation was sounded due something else the procedure (and I kid you not) was to take a deep breath, cut the hose with an axe and run like fook! I swear I am not making this up.

Incidently, if you think I'm being over cautious about safety, the guy in this first picture proly thinks he's safe cos a boulder never fell on his head before and they guy under the car, in all probablility, hasn't ever slipped a wrench and skinned his knuckles and jumped backwards whilst working under a truck before hehehe

[Weldtutor]

Originally Posted by ImanCarrot rofl Nitrogen leaks are truly deadly in enclosed spaces.. You should be ok in a well ventilated area I spose... the guy working under a truck

The various welding & cutting gases used certainly can be hazardous.

Ventillation & respirators are often required for safety.

A friend recently collapsed (but survived) in his well insulated & tightly closed shop, after his propane heater reduced the oxygen to a dangerous level.

............... under the truck, I see an arc & a welding machine in front of it.
Hundreds of times I've been asked "do those sparks hurt?"
My usual answer, "yes, but not as much as smacking your head on the chassis!" " Best not to jump."

[blackhollowmfg]

Not to mention it looks like he is welding on or near the gas tank!!

[vladdy]

If you are thinking about the benefits of using different gases for various purposes with a plasma, yes it makes a difference...
You can tailor a specific gas or gas mix for each application such as light sheet, heavy straight cuts [say up to 6" thckness], or even engraving with a plasma..
If you have a healthy budget, look at the esab M3 series...very nice..
You can also get quite a bit of info there about the benefits of varying the gas or gas mix for each part of a cut process..
They sent me a thick folder on this system, [M3] a couple of months ago, looked at it for a while, and realized my application [and budget] doesn't support thier system..
kept the cap though, nice cap..

enjoy..

[x6xtyx9x]

The composition of AIR....
Component
Symbol
Volume
Nitrogen
N2
78.084% 99.998%
Oxygen
O2
20.947%
Argon
Ar
0.934%
Carbon Dioxide

CO2
0.033%
Neon
Ne
18.2 parts per million
Helium
He
5.2 parts per million
Krypton
Kr
1.1 parts per million
Sulfur dioxide
SO2
1.0 parts per million
Methane
CH4
2.0 parts per million
Hydrogen
H2
0.5 parts per million
Nitrous Oxide
N2O
0.5 parts per million
Xenon
Xe
0.09 parts per million
Ozone
O3
0.07 parts per million
Nitrogen dioxide
NO2
0.02 parts per million
Iodine
I2
0.01 parts per million
Carbon monoxide
CO
trace
Ammonia
NH3
trace


So heres a question how can nitrogen hurt you if it makes up that much of air... and be heavier than air?? Anyone have chemistry experience?

[Weldtutor]

Originally Posted by x6xtyx9x So heres a question

You would no doubt find your answer if we put you operating a plasma arc cutter, in the closet mentioned previously in the thread.

[massajamesb]

Nitrogen is not harmful to you while in the air you breathe, it is harmful when there is not enough oxygen present with it.

I am not a chemist by name, but more by trade. I treat water, not cases of asphyxiation. The only asphyxiation I am familiar with is that of Cl2 overdosage. It too is heavier than air, but is also extremely corrosive.
it will sit in your lungs, burn your lung tissue, and contaminate your bloodstream and deprive it of oxygen. But, that is not what this thread is about.

Here is a somewhat- helpful link for you.
http://www.csb.gov/completed_investi...en-6-11-03.pdf