Shielding gas

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HiI recentely purchased a mixture of Argon and Co2 shielding gas tankAfter a few hours of use, in a span of maybe three weeks time, the Co2 has run out (or at least, that's what the gauges indicate...)The Argon level is no where near the empty mark, I haven't noticed any difference in the quality or behaviour of the welding. I admit I'm not an experienced welder, before this I had never used shielding gas.My question is, do I keep on using the tank until the Argon runs out, or do I stop using it, and get it refilled with the carbon dioxide mixture.Should there be a noticeable difference in welding with just Argon as suppose to Argon/Co2. Is it a normal occurence that the Co2 runs out before the Argon?                                                                                      Than you all for your help!AldoLast edited by abarone300; 07-09-2008 at 10:47 AM.
Reply:When you said you purchased a mixture of Argon and CO2, do you mean that they were in the same tank?  Or did you purchase seperate tanks, one with Argon, the other with CO2?What type of welding are you doing?Are you welding on mild steel?Have you checked for leaks at all of your fittings using soapy water?
Reply:Yes, one tank. At least that's what the store said. Initially the gauges did indicate That!Autobody sheetmetal (1/32" to 3/32") I'm in the process of restoring my '79 PontiacYes, I did the soapy water test, after I connected the the gauges and supply hose. And checked OKLast edited by abarone300; 07-09-2008 at 11:10 AM.
Reply:weldrwomnAre you saying that there is no possible way that Co2 could have been used up, and that only a leak could have caused that?Come to think of it... I did leave both valves open on one occasion. Could the gas have escaped from the gun?Is Co2 lighter than Argon?Last edited by abarone300; 07-09-2008 at 11:26 AM.
Reply:since the gasses were mixed in one tank, you are not going to lose just one of the gasses.  How did you arrive at the conclusion that just the co2 was out?
Reply:Woa, hold on there abarone300,you are not correctly understanding what the gauges are telling you, as weldrwomn says, the gases are mixed and you can't flow one without the other.So, let's assume you have pressure regulator/flow meter that consists of two gauges.  One gauge should read the pressure in the bottle in pounds per square inch (psi), this shows how much gas mix is in the bottle.  The other gauge should read flow rate in cubic feet per hour (CFH).  Is this what you have?
Reply:Is it April 1st?Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Aldo,You have one tank of gas.  In this case, you have one tank of gas which is a mixed gas of argon and carbon dioxide (which I'll guess is most likely the common MIG gas for steel short-circuit transfer welding, C25, which is 75% argon and 25% CO2).The tank either has some gas in it, or it does not.  Without some fancy-scmancy-expensive temperature-and-pressure manipulations, there is no way for you to lose/use one of the mixed gases without the other at the same time.  Because they are mixed in the tank.Picture a cup of coffee.  You put some milk in it and mix it.  Can you get the milk out of the mix now and just have black coffee?  Not really.If you have a reasonably sized homeowner tank (somewhere between 40 and 80 cubic feet of volume) and you used a reasonable gas flow rate while welding (around 20 CFH or so), you will only get somewhere between 2-4 hours of arc time with the tank of gas.  Example: you have a 40 CF tank and your gas flow rate is 20 CFH.  You will get approximately 40 CF / 20 CFH = 2 Hours of arc/welding time with that tank at that flow rate.If you have a leak somewhere, then you will lose gas and the tank will be empty sooner than you think or expected.
Reply:I guess I'm miss reading the gauges, I was under the impression that one of the two gauges indicated the pressure from the Argon gas, and the other gauge indicated the Co2 pressure...my mistake When I first connected the tank, both gauges indicated pressure, including the one I thought was the Co2, it's "pressure" gradually diminished and  went to empty, in a three week time spanI suppose the two gauges don't do the work I thought. Please set me straight, and tell me what those two gauges are there for...                                                                     Thanks
Reply:Ok, guys I get it!One measures PSI, and the other measures CFH. Why do you think the CFH is at 0, and the PSI gauge is indicating over 100 psi?Sorry about the confusion, I should have familiazed myself with the gauges a little better, before asking questions!
Reply:Hey BroccoliIt's not April 1. Stick around, I got a lot more dumb questions coming!Aldo
Reply:Yep, that stuff goes pretty quick esp is the small consumer bottles. Make sure to shut the valves off when not in use, and also open the valves up to the end stop when using them, sometimes a valve can leak through the packing if not fully opened. Gases tend to disolve, proof is the air we breath, nice blend of Nitrogen, Oxygen, Argon, CO2... all stays nice and mixed.When your gas gets low you will notice the bead bubble up and get ugly. Always seam to run out 5 min after the store closes saturday afternoon with some jobs I want to do.
Reply:There should be a set screw which is how you set the chf.  If your wire feeder has a purge button, press it and the needle or little ball (depending on which type of gauge you have) should go up to where you have the cfh set.  If you don't have a purge button, pull the trigger on your gun (make sure that the drive rolls are disconnected and that the tip of the gun is not resting on your table) and you should get the needle or little ball to move where the cfh is set.  When the gas is not on demand, you might not get a cfh reading.  Again, it all depends on what type of flowmeter you have.
Reply:Originally Posted by abarone300Hey BroccoliIt's not April 1. Stick around, I got a lot more dumb questions coming!Aldo
Reply:Are you planning on sharing the beer?
Reply:Originally Posted by weldrwomnAre you planning on sharing the beer?
Reply:All this talk about beer is making me thirsty...I might have to take a trip to the fridge before too long  To bad I am nowhere near L.A. or I might have to look you up Mr. Broccoli
Reply:I'm a little unclear about the CFH  purging. I'll check the welder when I go back to the garageI do have a better understanding of the regulator gauges now...Thanks again guys!
Reply:Originally Posted by abarone300I'm a little unclear about the CFH  purging. I'll check the welder when I go back to the garageI do have a better understanding of the regulator gauges now...Thanks again guys!
Reply:Originally Posted by weldrwomnAll this talk about beer is making me thirsty...I might have to take a trip to the fridge before too long  To bad I am nowhere near L.A. or I might have to look you up Mr. Broccoli
Reply:I'll drink to that - Happy Birthday!
Reply:Happy Birthday, Ed!Welcome back, welderwomn!  You haven't posted or been around in a while.Aldo, Even if your machine doesn't have a "Purge" setting, you can just turn the wire feed speed all the way down and then pull the trigger on the torch/gun.  You might waste a few inches of wire that way, but it's quick and easy to do and works just fine.  Note, the wire will be electrically 'hot' when you pull the trigger, just like when welding.  So take the appropriate safety precautions.Another way to "Purge" the gas line is to open the drive-roll arm/toggle/whatever and then pull the trigger.  That takes a few more seconds than just turning the feed speed all the way down.And all this talk about purge and CFH has to do with the fact that the flow gauge/regulator -may- show a different flow number (depending on the gauge type, etc) when gas is actually flowing through everything as opposed to when the gas is just pressurizing the system but not flowing.  Usually the flow-rate number on the dial gauge will drop a bit from the pressurized state to the flowing state.  An actual floating-ball flowmeter needs the gas to flow to measure the flow rate, the dial-gauge flowmeters will usually show a number even when there is no flow.You need to measure or adjust the flow rate while the gas is flowing, hence one reason for the 'purge' setting.  The other reason is to actually purge the air out of the torch and have shielding gas 'ready to go' when you actually weld.  If you try to weld with air coming at the weld instead of actual shielding gas, those first few seconds or so of weld will be crap.  YMMV.What kind of beer are we drinking btw?