[exnailpounder]

At what pressure does everyone else change their bottle at? I was welding aluminum yesterday and my bottle was getting down to about 200 psi and my welds started to get a little funky. Started getting pepper flakes and instead of shiny bright beads, they were a little grainy. I switched bottles and all that went away. I like to squeeze all I can out of my gas but I never had that happen before. I always keep my flow at around 15 cfh and that never dropped so I am wondering if the last little bit of gas gets contaminated somehow. I ran a little bead on some mild steel and it welded just fine before I switched bottles. It's no big deal, but I am scratching my head.

[Poland308]

I've noticed the same thing. I change bottles if i start to notice anything like you described. My tungsten seems to crap up extra fast when I get down to the end of a bottle even if the flow rate doesn't drop. As soon as I get down around 500 I watch it pretty close. Since I'm often on site for customers I'll change out at anything below the 500psi depending on where I'm at in a project or if it's close to the end of a day.

[Otto Nobedder]

What's happening here is usually moisture in the gas... The filler skipped evacuating the bottle to remove moisture for who knows how many fills... it's a common shortcut at the filler. I don't fully understand the physics behind it, but as bottle pressure drops, the saturation point (how much moisture it will hold) of the gas increases, so you get more water vapor in the gas coming out of the bottle, and this craps up your weld.

Steve S

[Fe3c]

Is there a filter you can run to get rid of the moisture?

[Otto Nobedder]

Is there a filter you can run to get rid of the moisture?

Yes.

Any dessicant type air dryer (Harbor Freight has them) can be placed inline between your flowmeter and machine.
They are inexpensive; Replace them when the color changes (purple, if I recall), or bake them at 250*F until they are clear again.

Steve S

[exnailpounder]

What's happening here is usually moisture in the gas... The filler skipped evacuating the bottle to remove moisture for who knows how many fills... it's a common shortcut at the filler. I don't fully understand the physics behind it, but as bottle pressure drops, the saturation point (how much moisture it will hold) of the gas increases, so you get more water vapor in the gas coming out of the bottle, and this craps up your weld.

Steve S

200 psi from a 300 cf bottle is, to me, a good amount of gas. Those bastards!

[motox]

same problem at 500
welding up an aluminum subframe and the weld was sh#t
replaced with new nice welds..
i will look into filters.
i use them for plasma cutter, prob the same thing
craig

[TamJeff]

I'll run it until the CFH starts to drop and then adjust the flow back up one more time until it drops again. If you think there is moisture in your cylinders, complain about it until they either give you a free fill or take extra care with your particular order. We had a gas salesman promise us the world and I made it clear from the start that questionable gas is not acceptable. If I have an issue, I remind him of that initial, and agreed upon promise and he has actually delivered a replacement instantly, and personally.

[xryan]

I don't change bottles until I can't get the flow I want, usually when it drops below 15cfh . You guys are definitely getting screwed if you're tossing out tanks with 200 psi in them. I'd be expecting a free fill.

[Poland308]

It doesn't happen often but when it does it's usually below 500 psi. Besides it only costs the shop $9. To fill my 125cf.

[rick9345]

when it is MT

[exnailpounder]

I don't change bottles until I can't get the flow I want, usually when it drops below 15cfh . You guys are definitely getting screwed if you're tossing out tanks with 200 psi in them. I'd be expecting a free fill.

How are we getting screwed when the moisture in them is ruining welds? I talked to my LWS about the problem and got a free fill on my 300cf bottle. Sounds like a win to me. You don't get very many repeat customers when you hand them a piece that has a goose-shit weld on it from moisture contamination. It costs me $6 dollars to change a bottle at 200psi. I have a minimum charge of $50 on any repair.

[xryan]

I'm not saying to weld with crap gas. I'm saying crap gas is unacceptable when it's no dry. Throwing out $6 of gas in the bottle is unacceptable. Do you throw out wire spools when there is 4lbs left? I'd expect a free bottle, that was filled properly.

Espically for those guys who aren't making money welding, supplies are expensive enough. No need to be theowing them out.

[exnailpounder]

I'm not saying to weld with crap gas. I'm saying crap gas is unacceptable when it's no dry. Throwing out $6 of gas in the bottle is unacceptable. Do you throw out wire spools when there is 4lbs left? I'd expect a free bottle, that was filled properly.

Espically for those guys who aren't making money welding, supplies are expensive enough. No need to be theowing them out.

I reported that I got a free 300cf fill. I haven't "thrown out" spools with 4lbs of wire on them because I use premium wire, not the crap like you get from Harbor Freight. Before I found my new LWS, who sell only high quality supplies, I have removed rolls of wire that I thought were inferior. There is a BIG difference in the quality of welding supplies for those that know the difference so I don't have to waste money buying junk. My new LWS is awesome and when I told the manager about the moisture problem, he gave me a free fill. Try that with Airgas. A 300cf bottle last me a lllooonnnggg time because I usually Mig weld(this is the Tig forum) and by the time I have used up all but 6 bucks worth of gas in that big of a bottle, I have made so much money off it that it 6 bucks doesn't matter. I like to weld as a hobby but found out I can get paid to do my hobby. It doesn't get any more fun than that. Nothing better than getting someone else to pay for your toys.

[rick9345]

Opinions and style everyone has one
Wide range of experience.
These forums are great.
agree,disagree always some thing to think about.
Thanks administrators for your time,truly a respectful forum.

[WJH]

My 125 CF Tank is down to 700 psi, is it time to switch it out?


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[Poland308]

Not unless your getting bad gas out of it. If your welds still look good then run it till you can't get any more out of it. If I change out my bottle early it's only in a production setting for a customer or if I'm getting shielding problems.