# How much Shield Gas?



## Boswell (Apr 1, 2020)

I have decided that I can't live without learning to weld. I just purchased a Hobart 210MVP MIG welder and I need to purchase a bottle of Shield Gas. I am thinking that my first project will me stand/frame to hold my longer metal stock. I am thinking to use square tube. probably 1/16th wall. I now need to purchase a bottle of Shield Gas (Argon/CO2).  My question here is What size of bottle should I get?  #2, #3 and #4 bottles are easily available.  How many hours of welding can I expect to get from a #2( 40cu. ft) or from a #3?

Thanks for any suggestions


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## tazzat (Apr 1, 2020)

Gas flow depends on the size of the nozzle. For the smaller 1/2" size nozzles you want generally 15-20 cf/hr.
For the larger 3/4" size nozzles you run about 25-40 cf/hr.

#2 @ 20 CFH give you around 2 hours of welding.


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## Alexander McGilton (Apr 1, 2020)

Just going off my experience of ordering for the Concordia civil labs. If we were talking TIG, I would say the biggest tank you are comfortable moving. Maybe have a spare full tank in storage. The rental fee and deposit goes up linearly with the size of tank while volume goes up exponentially, the math is not exact but you get the idea that bigger is better. And especially for TIG welding of Al, you are just screaming out argon. 

For mig, the Tank never seams to run empty, manly because the productivity is so much higher for the gas consumed, we don't have enough steel to through at the welder to consume so much to notice. So you can get a way with a more portable tank. 

Though your greatest hurdle may be the delivery and return process. So what is the biggest cylinder you can pick up and put in your vehicle?


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## Janderso (Apr 1, 2020)

I bought my tanks,
I don't like to run out so I bought the 330Cft for the Mig =75%co2 25% argon and for Tig I have the 244Cft 100% argon.
I need help to load and unload them = way too heavy.


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## benmychree (Apr 1, 2020)

I have always used straight CO2 for mig; being as its a liquid charge in the cylinder, it lasts very much longer than gas mixtures and gets better penetration, the downside being that there is more spatter and the weld finish is a bit rougher.  I have been retired for about 9 years now, and have not done a lot of welding, but I am still on the same cylinder of CO2.


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## Janderso (Apr 1, 2020)

I had forgotten about that (gas seperation). The welding tips and tricks guy always "stirs" his tanks when he changes them.
So far, no issues.


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## ericc (Apr 1, 2020)

One hour of welding goes by pretty quickly.  You need to be decisive and move fast.  I got along for quite a while with a 20 cu ft tank, but you have to be on your toes.  And, you have to put up with running out on a weekend.  With a larger tank, like 40 cu ft, things are much more relaxed.  Even with two tanks, I am extremely sparing with TIG welding, using it mainly for tack welding before using the stick welder.  With garage sale rods, nothing beats a stick welder, but if you're "on the clock" the MIG keeps you moving.  Also, cost for gas is less per foot of weld.  I'm not on the clock, and a lot of people who think they are really aren't.


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## pontiac428 (Apr 1, 2020)

If I were a beginning welder, I'd want a 150 cu. ft. bottle as a minimum.  I'm not, so I have two each of the larger bottles in the range and can mix my own argon/CO2/helium (Smiths proportional mixers). I hate running out of gas, since it always happens on Saturday or Sunday (The Law of Murphy) and I can't get to the welding supply during the normal work week very easily.


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## Ken from ontario (Apr 1, 2020)

I recommend buying your own bottle,  a (Q-80CF) size Argon/co2 is only 30 inch high , a perfect size bottle to strap or chain to a small welding cart, not too heavy or too tall, holds enough gas to last a few training sessions and a few small projects. this is the smallest I would consider in a hobby setting.
Straight  co2 (as benmychree said)  gives great penetration but IMHO the Argon/co2 might be a better choice for  someone who is just starting to learn.


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## Cadillac (Apr 1, 2020)

I second the largest tank you can handle. And have a backup never fails you’ll run out in the middle of a project.


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## Aaron_W (Apr 1, 2020)

I bought a 20lb Co2 for MIG and a 60CF argon tank for TIG. These are relatively small cylinders, about 2-1/2 feet tall 40-ish pounds but I need to move my cart a fair distance to do any welding and didn't want to deal with large heavy cylinders. My local gas supply is easy to work with and only about 15 minutes away. Since they are small I could easily fit both cylinders in the car if for some reason the truck was unavailable.

A 20lb Co2 is approximately 175cuft, so with a small MIG welder 5 or 6 hours of continuous welding. Co2 is much cheaper than the Co2 argon blends. You do get a volume discount on larger cylinders, but will also have to make a larger purchase (less frequently) when you do fill up.


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## Janderso (Apr 1, 2020)

Have you ever forgot to turn on the gas?
 looks like a monkey's butt.


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## Boswell (Apr 1, 2020)

Thanks everyone for the input. I am thinking that the #3 is the right balance between size and convenience.  I expect that over time, I will get a second bottle and or a bigger one. 

I also expect I will be back here with other questions


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## Ulma Doctor (Apr 1, 2020)

you can never have a large enough tank as far as i'm concerned 
i get the largest trimix cylinders, i think they are 225 cuft, if i'm not mistaken
i get the next size smaller for Argon, and the next size down for 75/25


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## Aukai (Apr 1, 2020)

Maybe start with a small spool of flux core, so you don't burn up any gas. Figuring out heat range, and wire feed will take practice, there should be a decal on the machine that will get you close, and you will need to bump the settings to fine tune. The better the sizzle the less splatter, and try to get as clean a surface as possible.


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## 7milesup (Apr 1, 2020)

I only TIG weld but it seems like I am always running out of gas.  I believe that I have a 160-ish cu ft tank.

As far as gas vs nozzle sizes.... A number 5 nozzle you should run 10 CFH gas.  Number 7 nozzle would be 14 CFH.   I just figured this out a little bit ago by watching the Fabrication Series >>>Fabrication Series Linky Here<<<. Up until that point I had been wasting a ton of gas by running 20 to 25 CFH. Only time you would need to turn it up is if it is windy or something unusual like that.


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## Z2V (Apr 2, 2020)

Boswell said:


> Thanks everyone for the input. I am thinking that the #3 is the right balance between size and convenience.  I expect that over time, I will get a second bottle and or a bigger one.
> 
> I also expect I will be back here with other questions



@Boswell, if you don’t already have a welding shop to deal with, the guys at Round Rock Welding Supply are the best in the Austin area, and closest to us. Based on my experience, of course.


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## Boswell (Apr 2, 2020)

Z2V said:


> Round Rock Welding Supply are the best in the Austin area


Thanks. I will check them out.


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## Joeman77 (Apr 2, 2020)

All my tanks are Q(80cf), in my area they're the biggest I can own and they're small enough to haul in the car. Gives you about 4 hours of working.
 And given the earlier reference to Murphy's law of after hours empty tanks, I set all the welders up to hold a second tank, except the small portable mig. I'd highly recommend a second tank instead of one large one, regardless of how careful you are eventually you're going to leave the valve open & forget and no matter how tight your system, it'll be empty, a second tank will save your sanity (and your bacon)!


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## Boswell (Apr 2, 2020)

a second tank sounds like good advice

thx


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## gr8legs (Apr 3, 2020)

If you haven't yet made the investment let me chime in here extolling the virtues of using CO2 as as newbie welder.

Benefits: Cheap!

Tradeoffs: As noted above, there's a bit of spatter with CO2 and the weld may not look like a journeyman did it.

Regarding spatter: Easy enough to avoid - either use an anti-spatter spray before welding or get one of Freight Harbor's pneumatic needle scalers and remove the spater with it after welding. Use the spray if you're not going to paint the joint (the spray is oil based and takes extra cleaning). The scaler is the bee's knees for removing the scritchies.

Using CO2 the weld may not be as pretty. Um, yeah - you're a newbie. Your first welds will look like a dog crawled onto your metal and crapped regardless of CO2 or bi- or tr- or quad- mixtures. Learn to weld and get your experience on the cheap with CO2 - and when you acquire the technique advance to the $$$ mixed gases.

Who knows, your first 20# CO2 tank may last a lifetime and give great results after you have honed your skills.

YMMV, have fun!

Stu


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## Boswell (Apr 3, 2020)

Thanks Stu.  I should have everything I need for my first effort this weekend. I don't have a lot of steel scrap but enough to get some practice with.


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## Boswell (May 10, 2020)

Well I thought I should give an update. I went with a 80/20 Agron/CO2.  As predicted my joints looked terrible but I improved with practice. Here are a couple of pictures of the results. It is not a accident that I am too far away for you to see the actual weld joints  Thanks everyone for your advice.


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## westerner (May 10, 2020)

Janderso said:


> looks like a monkey's butt.


I always thought they looked like electrically popped metal popcorn. Complete with fluff, pockets and foamy texture. 
I have seen it more times than I care to admit.....


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## erikmannie (May 11, 2020)

I use 80 cubic feet (Q sized) cylinders of C25 and 25cfm, so that is over three hours of continuous welding.


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## General Zod (May 15, 2020)

erikmannie said:


> I use 80 cubic feet (Q sized) cylinders of C25 and 25cfm, so that is over three hours of continuous welding.



CFH.

Continuous, yes.  With lots of starts and stops?  Hell no.  Lots of starts waste shielding gas due to the volume that gets stored in the hose and then PUFFS out at a much higher rate than what the flowmeter is set for.  Listen carefully and you can hear the initial blast (and also feel it if you're careful enough) a lot stronger than the residual metered gas flow.  The more starts you do, the more is wasted.


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