Before any flames start, here's my delema. I got an 80cf tank full of the co2/argon mix for <U>free</U>, as in I own the gas and tank. I originally started with a mig and a 20cf bottle of co2/argon mix - which is empty for the 2nd time.

I got a harbor freight TIG welder (because I have no money), and want to play around with sch10 SS tubing, as well as play with backpurging. I want to fill the small tank w/argon, but can't spare money for diverter valve as well as trading in a big, full tank of co2/argon mix. I mig to much to make it sensable.


My question amounts to this: is backpurging an SS sch10 manifold with co2/argon better than not backpurging at all? What pros/cons over argon as well as no backpurge?

 

NO you can NOT use any amount of co2 to purge with.You can only use pure nitrogen or pure helium or pure argon .Nitrogen is not inert so you can't weld with it.But you can purge with it.Nitrogen is one electron shy from being inert.
By using any co2 at all is the same as not using anything.

 

If you can afford it, get a nitrogen/hydrogen mix for backpurging on 304.

90/10 will provide superior welds to straight argon or straight nitrogen.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by need longer days &raquo;</TD></TR><TR><TD CLASS="quote">NO you can NOT use any amount of co2 to purge with.You can only use pure nitrogen or pure helium or pure argon .Nitrogen is not inert so you can't weld with it.But you can purge with it.Nitrogen is one electron shy from being inert.
By using any co2 at all is the same as not using anything.</TD></TR></TABLE>

Thats basicly what I was looking for.

The nitrogen info is great too, as I'd assume its a lot cheaper than argon (noble gas vs gas making up most of our breathing air). I guess my biggest issue is cost of the tank, vs cost of the gas. I'll still have to buy a tank or waste gas.

 

if you set your tubing correctly you can eliminate using filler rod when purging and get good welds, this can save you money of filler rod.... just my 2 cents

 

its so there wont be oxidation and there's obviously oxygen in there, lol

 

what

 

CO2.
there's oxygen in that compound. the point of purging is so there is no oxidation.

-derek

 

CO2 is already at its greatest reduction state. How is it going to oxidize the metal? It is not going to spontaneously turn into monoxide.

 

the presence of oxygen would oxidize the metal, hence the name.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beepy &raquo;</TD></TR><TR><TD CLASS="quote">CO2 is already at its greatest reduction state. How is it going to oxidize the metal? It is not going to spontaneously turn into monoxide.</TD></TR></TABLE>
Dioxide you mean.And i'm pretty sure that the O in CO2 stands for oxygen.Anyway the bottom line is NO don't use 75/25 to purge with.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dfoxengr &raquo;</TD></TR><TR><TD CLASS="quote">the presence of oxygen would oxidize the metal, hence the name.</TD></TR></TABLE>


What he is trying to tell you is that the outer electron shell of a CO2 molecule has every spot filled. Thus the oxygen atoms are not going to break off and bond with the steel.

 

http://www.arcraftplasma.com/w...s.htm

read under "argon makes an impact"

there is a lot of heat there, and CO2 can be ruduced with heat as well.