Nitrogen purge to prevent flame ups?

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#1

Would it be possible to purge the chamber with an inert gas to prevent flame ups and charring? Maybe have a port on the chamber to connect a tank of compressed nitrogen or argon? No oxygen, no flame, no charring.


#2

Not sure how feasible this would be, but I like the idea.


#3

I buy the no flame, but you will still char.

“Burning” wood with no oxygen is actually how they make charcoal.

But I like the idea. You could shield your cut area with a bath of inert gas. Much like welders do. I would be interested in the results.


#4

I had the same thought, I have a CO2 tank for pushing kegs that is unused.
Considering the cost of extinguishers, it costs $8.00 to fill it.
Placed by the air intake of the laser, a crack of the valve should purge the interior of oxygen enough to kill flame.

Perhaps even a manifold of sorts to connect the tank and regulated to bathe the laser interior so that even material that has a propensity to ignite could be used.


#5

Good point about charring occuring even in low/no oxygen.


#6

I used to operate my laser without air assist…would often have flareups.
Now that I use air assist…I have not had any…so if it works like its supposed to, you shouldn’t have to worry that much to prevent them.
I will say that I use a higher pressure than a small aquarium pump. At least 15 psi
Not sure what psi the GF will have.


#7

I know that CO2 in air is not going to behave the same as CO2 in a tube, but I do wonder whether there would be any absorption issues. Only one way to find out…


#8

Seems like the idea of an inert gas purge came up here maybe 6 months ago so there might be some good discussion in past threads. The idea sounds intriguing but I’d want to do some due diligence first and figure out the cost of running a purge gas at flow rates that are effective for preventing flames or combustion.

As of a few years ago, a standard size 200 cylinder of high purity CO2 was about $100 and contained 65 lbs of CO2, which translates to about 530 cubic feet of CO2 gas. Lower purity CO2 would work as well and probably be quite a bit cheaper, but you might still find that you are going through an awful lot of gas if you use the laser much.


#9

In my opinion this would be a fairly moot point. After cutting with and without air assist, I can tell you there is a large difference in flare ups. As in there aren’t any. Charring, however, will depend on the material you are using and I don’t think any amount of gas will prevent that from happening. You are removing material via heat from neighboring material. As the laser cuts in deeper it’s creating the channel between the two pieces of material which is amplifying the heat and the beam will be making proximal contact with the material outside of the kerf.

The only possible concept I could see for keeping a clean edge would be to start at a larger perimeter and slowly remove all of the material in an inwards pattern. Maybe even a multiple pass external engrave, but you will more than likely still get discoloration from the kerf heat and off-gassing from the material.

Ultimately, a CNC router could be a better option if clean edges are a requirement.


#10

Made exactly the same suggestion mid December, thinking about photographs being cut into jigsaw puzzles. Spike pointed out the charcoal inconvenient fact.


#11

Be careful with using nitrogen and especially argon. Even with a vent to the outside, argon will often settle to the floor and can suffocate small children or pets that are down at that lower level. This is no joke. I work with a glovebox that is repetively purged with nitrogen and argon and without purging the argon that has accumulated on the floor, I have nearly passed out when picking something up from the floor. Argon is somewhat difficult to purge from your lungs without bending over to let it flow out of your lungs.


#12

Thats good to know…:scream::grimacing:


#13

a dear friend of mine suggested pulling a hard vaccum inside the glowforge as a solution to a whole host of problems.

Needless to say she’s a physicist, not an engineer. :slight_smile:


#14

That would also make the Glowforge virtually silent. Two birds, one laser.


#15

Abounding the ultra pro model starting at $20,000. It doubles as a chamber vacuum for you sous vide fans!


#16

there goes the pass-thru slot


#17

nah, force field. Ive seen em in movies like star wars and star trek. Im sure a tiny one over the pass through wont use much energy


#18

The books DUNE have my favorite force fields. And in my opinion the most useful.


#19

It better be a hard vacuum, as a partial vacuum is going to be chaos with corona discharges throughout the machine. :slight_smile:


#20

I do know at least a couple of large companies are using laser cutters for this or something very similar - so it is possible to produce a product like you’re speaking of that is commercial quality.