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Old 10-04-2006, 07:41 PM
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welding gas question

I am a relative new welder. I bought some 75/25 gas this week. I was wandering what pressure I should set the gas on. Does it matter what I am welding as to what it needs to be set on. Right now just sheetmetal. Please help.

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Old 10-04-2006, 08:03 PM
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I usually set my gas at 15 - 20 depending on where I'm at welding. If there's any chance of the wind blowing I'll turn it up more.
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Old 10-04-2006, 08:26 PM
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First you have to check on what your regulator reads, is it CFH (Cubic Feet per Hour)or is it PSI (Pounds per Square Inch).

This is right out of the American Welding Society guide.

25-30 CFH or 3-4 PSI. I have never seen a PSI guage on a MIG but I guess they must exist or they wouldn't tell us.

Brian
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Old 10-04-2006, 08:43 PM
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To answer your other question, the flow rate of your gas does not typically need to be adjusted up or down with your metal thickness. The real requirement is that you're just just fully blanketing the arc and molten weld. Big block's comment about breeze is right- a little extra air movement may require you to increase your gas flow. If you start seeing some ugly welds, increasing you gas flow would be the first thing to look into.
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Old 10-05-2006, 07:12 AM
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Actually turning up the gas flow does next to nothing to help if you are in a breeze. The misconception that the gas is blown away leading to porosity makes one want to correct the problem with more gas flow but in reality this helps very little or not at all. The problem is not the breeze blowing away the gas shield it is that the gas becomes contaminated with atmospheric gases and unfortunately turning up the flow does little to correct this, the breeze will still contaminate the shield even with higher flow. The best solution is to shield the weld from the breeze.

Last edited by oldred; 10-05-2006 at 09:15 AM.
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Old 10-05-2006, 01:03 PM
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Not adjustable

I've never seen an adjustable regulator on a MIG - the gauge only gives you an indication of how much gas is left in the bottle by PSIG. My Harris regulator instructions say do not adjust - and this is the same regulator all Lincolns use (at least the smaller units). When I took a night course to "learn" how to MIG, their mega size units had a non-adjustable regulator as well. You turn the valve all the way on. Period.

Dave

Yeah, I know - someone has an adjustable regulator and will prove me wrong. Again !!
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Old 10-05-2006, 01:56 PM
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Most MIG regulators (more correctly called flow meters) are adjustable and use a tube graduated in CFH. The small regulator type units are commonly used on the smaller MIGs and are ok for light welding with smaller leads and nozzles but for larger welders and longer hoses you really should use a good adjustable flow meter. These small units usually, as pointed out, read only tank pressure and are pre-set and non-adjustable. A lot of shops use non-adjustable or lockable flow meters because of the need to control the amount of gas wasted which can be substantial if you have several welders running with too much flow. I know from experience that it seems the first thing the welder wants to do is to twist up that flow when something goes wrong (it almost never solves the problem) but when things are going good they never seem to think to turn down excess flow which is in all probability why those industrial welders in that class had non-adjustable regulators.

Last edited by oldred; 10-05-2006 at 02:04 PM.
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Old 10-05-2006, 02:44 PM
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My 110 Lincoln was adjustable but didn't have a flow meter on it. I bought a flow meter at a welding shop and added it to make sure that I wasn't wasting any gas.

Danny
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Old 10-05-2006, 03:08 PM
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I have never seen a MIG without an adjustable reg. Mine at home has a flow meter along with the reg. But here at work the Miller 130s and 135s of which we have about eight of also have adjustable regs. Now, the newer 130s originally had a reg without a knob on it, you adjusted it with a screw driver as it had a screw to turn.

Brian
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Old 10-05-2006, 05:51 PM
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MartinSr, Even the "non-adjustable" units can usually be adjusted with a screw driver, most of them anyway. Since most don't have a flow meter or even a secondary gauge to read regulated pressure it would be guess work without a meter of some type to set it by. These things are just the bottom end of the scale low cost to go with a low cost welder but for most small machines they will work just fine and probably save the operator a bunch of gas that would be wasted by setting the flow too high which is a common mistake. Setting the flow on 30 when 15 would work just fine will cut your welding time per bottle in half.
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Old 10-06-2006, 08:06 AM
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I posted that my Lincoln is adjustable but it is with a screw with a cap over it. I kinda like it that way because I can adjust it and don't have to worry about anybody changing it on me (I have four grandchildren).

Should the gas be adjusted while not in use or when the gas is flowing? I haven't looked but I'm assuming the flow rate would go down when the welder is in use compared to just sitting idle.

Danny
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Old 10-06-2006, 12:07 PM
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When the welder is idle it should not flow at all
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Old 10-06-2006, 12:13 PM
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Mine is adjustable. 12 year old Lincoln 125 Mine has 2 gauges one before and one after the regulator just like the torches. No flow tube. Same goes for my Tig Lincoln 175.
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Old 10-06-2006, 12:15 PM
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Red-
I think he's talking about setting the pressure. It wont flow until the trigger is hit, but the DIAL gauge reads XX #s whether its flowing or not. It will drop when you hit the trigger.
Flow guages need to be set while flowing. The flow gauge is a clear tube with a ball inside. The dial gauges look like a torch gauge set.
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Old 10-06-2006, 04:26 PM
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The dial guage marked with CFH is what I have. Shouldn't it read the same as a flow meter?

I was talking about the guage reading sitting still vs while in use.

Danny
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