Dumb question about gas

[notenuftoys]

I've always wanted to learn to weld and few months back my wife found a Hobart 175 for sale locally for a good price so I grabbed it. My youngest, a junior in high school, just started a 2 year dual credit welding program.

Now we're starting to plan out how we're going to weld at home and I have a question about gas. How long does a bottle usually last?

Sure, this might be a tough question to answer based on usuage, but I was a little surprised at the cost. Could I expect an average size tank would last a few years for a hobbyist? Any suggestions, recommendations?

We don't have a lot of money laying around so I'm trying to be smart about how it's spent. I can use flux-core, but from what I've read it's not quite as clean.

 

[J.C.]

I have always looked at it this way... Take a look at your flow rate (I use litres/minute here) and look at how much the bottle contains and then you'll have how many minutes of welding you'll get out of it. Approximately. I don’t time my welding, though, so I have never actually tested how accurate it is.

 

[jchev53]

I use my welder maybe once a month for all different odd jobs around the shop. The bottle is about four feet tall and I haven’t re filled it in about 5 years. If your son is learning to weld I would expect your usage rate to be higher. Also remember to turn the bottle off when you are not using it.


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[Old Man Roger]

It's worth it. Just keep the regulator turned only as high as you need it and turn the bottle off when you're not welding. A quick google search got me this.

Your flow rate is usually set from 10-20 cfh which on average if you had a 250 cf bottle would last for 10-20 hours of welding non stop. That would work out to about 2-4 days of serious welding.Dec 8, 2012

That would be welding 24 hours a day.

 

[The Tool Tyrant]

Tough question is right! Prices vary (sometimes drastically) between distributors. As you stated, longevity is solely dependent upon usage. I'd suggest running C-25, although more costly than straight CO2, you'll get much less spatter.

Ideally, if you know anyone (hence good friend) that uses a lot of welding gases
in their business, they will get a much better price break, so buy through them.
I have an employee that has a TIG machine at home and brings his empty cylinder in that I exchange for a full and just charge him our rate.

 

[koditten]

I can build 20 trailers like in my avitar pic. That takes me close to 15 months to go thru a a big can.

A small can will last you a long time. Don't sweat the cost of the gas...everything else is gonna add up. Lol.

 

[DieselNut88]

It will probably last you a few years if your only doing small projects.

 

[dr_clyde]

A small cylinder of gas (125 cf) should last a hobby shop for several projects. At least a month of regular practice and use. I run the big 330 CF cylinders in my shop and we swap a couple out a month, and that’s with a couple guys running a welder 8hrs a day.

 

[ClappedOutBport]

Usually you lose most of it when you leave the tank on, at least for me. It's worthwhile to make sure your welder has 0 leaks. I found a small one, and now it will hold the pressure in the line for a month. I wish I could say the same for the other welder...

 

[Downwindtracker 2]

There has never been a dumb question. There have been dumb answers though.

 

[snyder]

I have a 4 foot bottle. I paid 250 and 60 to have it exchanged when empty. A bottle will normally last me two small rolls of wire. I don't know if this is typical.

 

[BigMike782]

I would suspect the manual for your machine will say 25 CFH but they are not paying for your gas. The gas does two things, shields the weld pool and cools the mig gun(not whip or stinger). With a 175 amp machine I would suspect you will be welding 20 gauge to 1/4" material. At the lower end of the range you could have someone turn the flow rate down as you weld and when you start to notice porosity, turn it up until it goes away and add a little for good measure. You may find 10 CFH is enough. At the the higher end you will likely need some gun cooling and may need 15 or 20 CFH.
Buy the largest cylinder you can as the price per cubic foot drops as the volume goes up.

 

[koditten]

I have a 4 foot bottle. I paid 250 and 60 to have it exchanged when empty. A bottle will normally last me two small rolls of wire. I don't know if this is typical.

That is a terrible consumption of gas. I usually get 2/3 of a 44 lbs roll of wire.

 

[MoonRise]

'last a few years'?

Only if you have the cylinder shut off and don't use it!

The gas will last until it is used up. Usually that is when you are in the middle of a welding project and the store is closed.

The time until the cylinder is empty depends on the cylinder capacity (how much gas is in the cylinder) and the gas flow rate and how long the gas is actually being used.

Example time.

If you have an 80 ft3 cylinder and your gas flow rate is 20 cfh (cubic feet per hour), then you can have the gas flowing (being used) for 4 hours.

80 ft3 / 20 cfh = 4 hours

That's 4 hours of actual gas flow time available from that 80 ft3 cylinder, at a flow rate of 20 cfh.

And yes, it is generally worth it to have shielding gas. You can't do MIG (aka GMAW) without it.

 

[Bretny]

Buy the biggest bottle your local welding supply house will let you own. Gas is cheaper the more you buy but you dont want to lease a tank. As for how long you can weld on one thank that can be figured out but why? Your going to weld mabe 30sec at the most at a time so unless you have a stop watch close by just watch the high pressure gauge.

 

[bdbecker]

If you don't want to be tied to your local weld supply house's banker hours of operation, an alternative source is Thoroughbred weld gas cylinders distributed through Tractor Supply and Northern Tool, if you have one of those stores nearby. It works the same as when you buy/exchange propane tanks for your grill - you buy the cylinder full of gas, and then when you exchange it, you only pay for the gas itself.

The nice thing with this option is that you can upgrade to a larger bottle as your budget allows, getting full credit for the purchase price of your smaller bottles. Say you spend spend $200 on a small bottle and wanted to upgrade to a larger one that costs $300, you'd only have to give them another $100 to cover the difference in cost. These are made-up numbers for the sake of example - you'll have to see what the actual costs in your area are.

I think the bottles may be a touch more expensive, but the gas price is competitive. Its actually $5 cheaper for me to exchange a bottle at Tractor Supply than Airgas right now. I'm happy to pay a little more upfront to be able to get gas at night and on weekends and not have to rent a bottle.

 

[Downwindtracker 2]

From other posts, there is a wide variation of prices and experiences about bottles. The small industrial ones I use at home are lot nicer to take in than the big ones we used at work.

 

[LeeG]

Just some back of the envelope calculations for how long gas/wire lasts
Welding 1/8" steel will have a wire speed of about 250 inches/minute
A 2 pound spool of .030 wire will have about 850'
So the amount of trigger time to use a full spool is about 40 minutes.
At a full 20cfh, you would use just under 13 cubic ft of shielding gas per spool.
So an 80ft^3 tank will last about 6 full 2 pound spools.

This should give you a ball park number for how much gas you will need. This seems to fit in with my experience, as I seem to use most of a 10 pound spool before I need to fill my tank.

 

[rsanter]

Depends on what gas you are using.
Also depends on the flow rate. Keep the flow as low as is needed for proper shielding and no more. Too high a flow rate can work against you.
If you are welding in an area where there is some wind or breeze, then use shielding panels or blankets to block that wind and you not only won’t have to turn the gas up but you will get a more consistent weld quality

 

[NUTTSGT]

I also have a Hobart 175 and use CR25. I bought/rented/leased a 80 cu/ft tank from the local place.

The 80cu/ft tank is probably going to be plenty for you and your son. However, he may go through more in the beginning. Your initial layout in cash with be paying for the deposit/tank rental, after that you swap out cylinders and only pay for the filled argon/CO2.

If you have a decent supplier, they may not question where the tank came from if you find one used....as long as it's "their" tank. This may save you some initial cash layout. OE Meyer, my local place doesn't ask my name when I come in, just what I need, we swap cash and bottles.

My oxy/acetylene tank come from a different supplier and they were hand me downs from family. When I asked about swapping as they were not in my name, the local distributor was like, " I don't care where they came from as long as they are (our) bottles. I guess that is the benefit of rural living.

 

[Robby321]

When done, tanks shut off, regulators (screw handle) loosened and drain the hoses at the torch. Don't leave regulator diaphragms under pressure........

 

[readhead]

I ran out of gas on a Sunday afternoon about four years ago so I switched to some flux core and finished up. I have been burning flux core ever since. Okay, I know, gas is a lot cleaner but since I am going to probably sand and clean the weld I don't care how much spatter there is. The irony here is that up to a year ago I had a full on commercial welding shop with probably 15-20 cylinders in the shop at all times and I could have swapped that cylinder anytime. We used a lot of flux core for structural and guardrails out on jobs. For what I am doing at home I don't miss gas at all.

 

[gte718p]

My oxy/acetylene tank come from a different supplier and they were hand me downs from family. When I asked about swapping as they were not in my name, the local distributor was like, " I don't care where they came from as long as they are (our) bottles. I guess that is the benefit of rural living.

It not like bottles have titles. Who ever has them owns them. You might have a rental agreement with your gas supplier, but actually tracking that to a specific bottle is impossible.

I've lived in 9 different places in the last 16 years. My exchanges always go something along the lines of, walk in tell the counter I want to exchange a bottle. They ask the size and the gas. I pay them and they tell me to drive around back and drop the empty at the loading dock and that Argon is is the third groups of bottles.

I have never has anyone check what I dropped of or what I picked up for that matter. The bottle I bought in Atlanta is probably still floating around in Atlanta. Currently I have an empty AirGas bottle, but I have had several different companies bottles over the years.

 

[Monza Harry]

Depends on what gas you are using.
Also depends on the flow rate. Keep the flow as low as is needed for proper shielding and no more. Too high a flow rate can work against you.
If you are welding in an area where there is some wind or breeze, then use shielding panels or blankets to block that wind and you not only won’t have to turn the gas up but you will get a more consistent weld quality

This is good advise, the more stable your air mass the less gas required I get away with down around 12-13 on my Regulator. Also gas bottles are "Dual Seat" that means there is a seat at the wide open position the same as shutting it off. This is important as you can loose a surprising amount out of the stem, odourless so how would you know? When a new to you bottle goes empty in 4 hours with only 1 hour of welding! [Many four letter words used in imaginative combinations that day] Always open wide and close tight. If your machine has settings for pre-flow and post flow you can try and optimise these, post flow will usually use more than pre-flow' Post-flow is to stop the surrounding air from coming rushing over your weld while the material cools to a less oxidable temperature Post weld marked off in seconds. So hoover when finished on the Important things (all of them). Pre-flow is for initial purge of "Air" from gun and puddle area marked in fractional/decimal seconds.
The good news is most hobbyist machines give no choices, so you will be as good as you can be. Mine are pre-set MIG and TIG the welder at work is full of choices. Harry

 

[NUTTSGT]

It not like bottles have titles. Who ever has them owns them. You might have a rental agreement with your gas supplier, but actually tracking that to a specific bottle is impossible.

I've lived in 9 different places in the last 16 years. My exchanges always go something along the lines of, walk in tell the counter I want to exchange a bottle. They ask the size and the gas. I pay them and they tell me to drive around back and drop the empty at the loading dock and that Argon is is the third groups of bottles.

I have never has anyone check what I dropped of or what I picked up for that matter. The bottle I bought in Atlanta is probably still floating around in Atlanta. Currently I have an empty AirGas bottle, but I have had several different companies bottles over the years.

The local guys want "their" bottle exchanged, that's all they care about. I think it might be more a hydrostatic test issues more than anything. . . . liability issue and tracking the bottles.

I know some guys here at GJ have mentioned having issues trading empty for full bottles if they we not "their" bottles. I'm glad to see another member not having issues when getting a bottle swapped out.

 

[Downwindtracker 2]

Here, each bottle has serial# . My son got a large green oxygen bottle given to him. When he moved out, in a clean up I took it down to the LWS , hoping to exchange the bottle with a tri-mix bottle. He looked it up. "Sorry, that's a leased one." " OK can you give it back to the company." "Sure"

In Canada, bottles have to tested every 10 years, even your propane ones. Besides leasing bottles, you can purchase them, out right or from a company. Mine are LA. With the company ones, the company has the responsibility for the test. It's just an exchange then instead of a fill.

 

[dr_clyde]

It’s such an odd thing to care about. I really don’t know why the welding supply houses care.

The money is in the gas. The cylinder isn’t worth **** compared to the gas you use. Wire, tips and other consumables are where the LWS makes their money. There’s no money in welding machines and chasing cylinders all over creation.