Mixing Argon & Carbon Dioxide

[awemawson]

I rent a large pure argon bottle from BOC for my TIG and also use pub type carbon dioxide cylinders with my MIG. Would it be feasible to bring the outputs of both regulators together to form a CO2 / Argon mix for mig welding to give a better shielding gas at a better price than the Argon?

AWEM

 

[dai]

flow meter on each bottle,then T them together
75/25 argon/co2
eg,7.5liters/min argon,2.5 litres co2

 

[shenion]

Yes, T them together. Best to have a a check valve on each as if one regulator is a higher pressure, the other will vent as it sees too much output pressure. Adjust both regs to about the same pressure and use two real flowmeters.

I mix mine here using a Smith gas mixer. Nice as I have gone through 3 bootles of argon and still have not had to refill the CO2. I will probably change to two flowmeters and T together as it will be simpler (mixer has slow leaks.)

 

[gordon stephenson]

Further to this post, even using good flowmeters would it be difficult to mix argon and Co2 at the percentages of Argon 97.5% to 2.5% Co2 for mig welding on stainless steel.Or would some mix that was in the ballpark be OK.

 

[TechnicAl]

You can buy very expensive mixers and even then you need very expensive analysers to ensure the correct mix.
I suspect that youre not doing coded work so the suggestions may work but remember its mostly Argon with a little bit of CO2........if its stainless a little bit too much and you will get a black weld.
Mild steel will be more forgiving probably 12 - 25 (maybe30) percent CO2 should be OK

 

[gordon stephenson]

Hello Al.
thanks for the reply, Every thing just for home hobby use, I have a BOC bottle for my mig and and a pure argon for the tig, I can get some Co2 for free and just wondered if I could make a set up to bleed a little into the argon to weld stainless with the mig,

 

[Paul.]

Some years ago we experimented with a diy type mixer with some success, Ar and C02 were piped via flow meters from the regulators into a small mixing tank, It was actually an old disposable gas cylinder with some fittings welded on, and another flow meter on the outlet to the welder, the simple logic was that the flowmeters on the inlet side could be used to regulate the mixture, It was never really meant to be a serious attempt, more a wonder if it would work kind of thing, as I recall it worked best with the outlet at the top, we had no method of testing the results other than trying to weld with it, and there may be some gas chemistry involved that a proper mixer deals with.
There was a marked improvement over pure argon, but not reliable enough for serious welding, probably ok for scabbing cars back together though.

 

[gordon stephenson]

Thanks again for your information guys. May just give the mixing tank idea a try one of these days,

 

[dannyp]

i have a mixing bottel, is actualy on old 10 ltr oxygen bottel. an my pikey pipe

the pipkey pipe is a pice of hydralic hose with the male bottel fitting of a reg on one end and at the other end it has a T piece with another male boand a pressure gauge on it.

i just mix gas of th pressures, onnect it up to the CO2 put a few bar in, add a bot of oxygen then top off with argon.

don't normaly fill it to a high pressure as i can easly refill it at any time and it's more for the portablity of small bottel and been abel to mix up a gas for heavy or light work as i please