what pressure needed for mig welding

[Powermandan]

What do the regulators on mig welders generally operate co2 at (PSI after regulation)?

thanks

Dan

 

[Justme]

Its rated in flow. Liters per min. Start at about 10 & see how you get on.

justme

 

[Powermandan]

I suppose i better explain, im totally new to welding so i may have got my wires crossed somewhere .

I want to use some old paintball kit that i have lying around to make a gas feed as i think it will work out cheaper than buying the disposable type bottles as i can use old 20oz pb co2 bottles which cost £1.00 per a fill and can be bought really cheap £5.

The thing is the lowest the regs tend to go is about 50 psi which may possibly blow the solonoid in the welder when im not actually welding.

the flow rate of the regs are usually really good but could be decreased if necessary.

 

[Drains]

Blowing the solenoid isn't the issue. Too much co2 and the gas will get way too cold for welding (that ice on the outside of the bottle means your welds will be bad) . Get a regulator from Weldequip and keep the flow as low as you can get away with

 

[Justme]

I guess a flow meter would do but ask Weldequip.

justme

 

[Powermandan]

Thank you for your help but i dont think you are quite getting what i am saying.

if you were to take the tube from the regulator that feeds the welder and stuck a gauge in the end of it what would the gauge read?


Thanks again

Dan

 

[Justme]

Thats the problem. Its not relievent to welders. Welders need a volume / flow of gas not a presure. So for the welder as long as the presure is reduced from the 2-300 bar to what the feed pipe can take the welder wont be fused. You then set the valve to FLOW a fixed amount per min. If I had to guess i would say that the presure is quite low (two or three atmospheres). Propane / butan is reged down to about 7-14 psi if I remember right & I guess that welding shield gas would be about the same.

The flow meter here can take 2 bar inlet presure. The argon reg on the same page has a max 7 bar output.

Justme

 

[Powermandan]

Thanks they much

 

[Justme]

2 bar = 29psi
7 bar = just over 100psi

Gas output at the torch seems much lower than this.

Justme

 

[cobminor]

Pressure is imaterial, you need a flow rate of about 12 liters a minute.

 

[Drains]

I'd use 12 lpm if I was outside. But with co2, no way. Too cold, too cold.

 

[Masked Marauder]

I never use a flow rate of over 8 lpm with CO2 and my welds are fine. Sometimes I am as low as 4 lpm if it is a very calm day.

 

[peter9763@tiscali.co.uk]

just a little note. unless you are using a siphon cylinder when Co2 welding you are likely to get porosity in the weld due to moisture in the gas. syphon cylinders take liquid co2 from the bottom of the cylinder, you then need a 250watt heater in the line to vaporize it to gas. I do'nt know if pub cylinders are the syphon type.