contaminated argon ?

[FABMAN]

guys,

in the past i have come across a bad, contaminated bottle of 75/25 argon/helium while tig welding aluminum. i would swap the bottle out and everything would be fine.

the past few days i have been having intermittent problems with the cylinder i am currently using. i could weld for a few hours with no problems, then all of a sudden i begin to have problems, like erratic arc, my tungsten turning blue/black after the post flow has stopped, etc, sometimes lasting for 30 minutes..
i do not have any fans pointed in my area, and am far away from the open garage door and have curtains on each side of me, so i know its not any wind blowing away my shielding gas. i have been welding in this booth for 4 years.
then within time it will start to weld good again...

so my question is, if its a contaminated bottle of gas, is it possible to get good and bad spots within the cylinder, or once a tank is contaminated will it be all mixed with no good areas ? this is the first time i have had a bottle that acted good at times, then bad at other times..

just curious.... its driving me crazy....

thanks

[Jigantor]

Do you have a leak in the hose or torch area?

Ji

[Sefro521]

Your gas was not properly mixed by your supplier!

[FABMAN]

Do you have a leak in the hose or torch area?

Ji

thanks.... i do not believe so....
how can i check for a leak ? can i hit the pedal, put my finger over the cup, to seal, and see if the flow ball drops to the bottom ?

[Jigantor]

Check from bottle to torch first with soapy water.
See if any bubbles.

Ji

[FABMAN]

Check from bottle to torch first with soapy water.
See if any bubbles.

Ji

thanks... will do tomorrow..

[Jigantor]

Like I don't know if that is it but check the basics first.
Grab the torch and see if the electrode is not tight, I have had problems with that before. Bits of copper flakes clog jet holes.
Again just strip the torch and see what you find starting at the hose to torch connection.

Ji

[MMW]

I have never had a bottle be intermittantly bad. When it was bad it was bad. I have had a tungsten become contaminated that seemed like a gas issue. After regrinding it & assuming that wasn't it I moved on to other causes but in the end I replaced the tungsten & all was well. Reground the original & put it back in, same problem so it got tossed.

I've also had a weak gas hose that would kink when holding the torch a certain way. This was very intermittant. I've also pinched the gas hose with my chair, the pedal, pulled it to tight trying to reach around something.

Crushed collet can also block the flow of gas.

Just trying to give you some other ideas if the obvious doesn't fix it.

[FABMAN]

wow guys, thanks for the tips....

when checking the hose connections for leaks, should i hit the pedal and purge the gas and cover the cup with my finger, to cause pressure, or just let it purge normally ?
and are you saying to squirt soapy water on the torch connection with the handle cover removed ? will it cause a short ?

thanks again..

[griff01]

guys,

in the past i have come across a bad, contaminated bottle of 75/25 argon/helium while tig welding aluminum. i would swap the bottle out and everything would be fine.

the past few days i have been having intermittent problems with the cylinder i am currently using. i could weld for a few hours with no problems, then all of a sudden i begin to have problems, like erratic arc, my tungsten turning blue/black after the post flow has stopped, etc, sometimes lasting for 30 minutes..
i do not have any fans pointed in my area, and am far away from the open garage door and have curtains on each side of me, so i know its not any wind blowing away my shielding gas. i have been welding in this booth for 4 years.
then within time it will start to weld good again...

so my question is, if its a contaminated bottle of gas, is it possible to get good and bad spots within the cylinder, or once a tank is contaminated will it be all mixed with no good areas ? this is the first time i have had a bottle that acted good at times, then bad at other times..

just curious.... its driving me crazy....

thanks

For starters, you are using the wrong gas. You should be using 100% Argon on aluminum.

Next, I have had 4 or 5 contaminated bottles of Argon. Once bad, the rest was bad.

Griff

Correction; I saw 75/25 and immediately read "argon/CO2" instead of argon/helium.
My bad. Sorry.

Griff