Experience refilling argon or 75/25 cylinders yourself?

   / Experience refilling argon or 75/25 cylinders yourself? #31  
Apologize for not having read every post here, but for CO2, refilling from lge to small is quite feasible...paintballers do it all the time and if you check out one of their websites you can find all the valves, scale (it's a weight thing) instructions, etc. As for MIG welding on the go, the Miller Passport provides exactly that capability, from "paintball" tanks that are refillable (and, if you overfill, you can buy and easily install the blow-out plugs.) I have a Passport and it works just as advertised ...incidentally, I would like to sell it...
 
   / Experience refilling argon or 75/25 cylinders yourself? #32  
The metal pails are used to catch sparks.;) That's why welders need helpers. We had a newbie in yesterday. They sent him to get a couple black #10 lenses... a couple red #10 and a couple pink #10 lenses. I was going to send him back with a pink welding helmet(ladies) explaining that the lens doesn't come separate. It was a Miller helmet so it would have been in the $250+ range. The boss might have fell out of his chair when he got the invoice.

Back to the topic, How can CO2 be filled to 1800 PSI since it's filled as a liquid on a weigh scale?
 
   / Experience refilling argon or 75/25 cylinders yourself? #33  
The metal pails are used to catch sparks.;) That's why welders need helpers. We had a newbie in yesterday. They sent him to get a couple black #10 lenses... a couple red #10 and a couple pink #10 lenses. I was going to send him back with a pink welding helmet(ladies) explaining that the lens doesn't come separate. It was a Miller helmet so it would have been in the $250+ range. The boss might have fell out of his chair when he got the invoice.

Back to the topic, How can CO2 be filled to 1800 PSI since it's filled as a liquid on a weigh scale?

If you look at a 50# co2 tank it will say DOT 3AA 1800 + * stamped into the shoulder of the tank. 1800 is the gas pressure above the liquid in the bottom half of the tank. The + means that the cylinder is within hydrotest specs for 5 years from the date stamped on the tank. The Star means 10 years from date on tank.. They fill to weight but when you put the regulator on it, It will show + or - 1800 #. That will stay fairly consistant as the liquid is turned to gas and then suddenly fall off to an empty tank.. Am I the only one on here that has worked at a Welding Supply & Gas Distributer?... A 50# co2 will last 5X longer than a 300CF tank of 75/25 at 1/3 the price. Sooo if you just repair old farm equipment and don't sell what you weld..Co2 is your gas plus it is Hotter than 75/25. The draw back is a little more spatter unless you have an inductance control or a Digital HD welder like a couple of mine which run CO2 with no spatter at all on anything including rust grease and paint. .
 
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   / Experience refilling argon or 75/25 cylinders yourself? #34  
Does this qualify? I've worked at 3 gas distributors. One of them , the largest in the world where I toured a $150,000,000+ cogeneration power plant (80 MW) and air separation facility that produces 1000 tons of oxygen per day. The complex will also have a 300-ton-per-day carbon dioxide plant to recover, purify and liquefy raw byproduct CO2. The power plant is powered by a 25,000 HP natural gas turbine. Natural gas was used because they use the exhaust from the turbine to produce 200 tons of steam per day to supply a monoethylene glycol plant that they also supply the power and 700-900 tons of oxygen/day to. Excess power is sold on the Alberta power grid.

The 1800 PSI is the safety rating of the cylinder not the working pressure. At room temperature a CO2 cylinder is about 850 PSI but it can be lower depending on a couple factors. If CO2 goes to 1800 PSI, how come on a Victor SR311 CO2 regulator/flowmeter, the maximum inlet pressure is 1500 PSI? Even then, the cylinder would have to be sitting in the hot sun well over 100 deg. to reach that pressure. CO2 cylinders are the same as any other pressure vessel and have to have generous safety ratings. On top of that the regulators have burst discs to vent excess pressure.
 
   / Experience refilling argon or 75/25 cylinders yourself? #35  
First thing that I'd do is to have a chat with management at your LWS to see if you could get a price reduction on the 20cf cylinder of 75/25. If you're anticipating high enough usage, they might adjust your pricing for you. One of the highest costs of a cylinder of gas is labor, and there's not much difference in labor to fill a 20 vs. an 80, that could be why the price is proportionately high.

Forget turning cylinders upside down, it's not safe, and at that high of pressure the two gases are going to still be mixed. If there was a higher percentage of CO2, the mix might de-stabilize. Standard N2/CO2 mixes for draught systems are generally blended at no more than 75/25 (Guinness) or 70/30 ratio. Higher ratios of CO2 can be blended onsite, but we don't see them as a packaged (cylinder) blend. I would assume that an AR/CO2 mix might react about the same. As stated before, CO2 in a high pressure cylinder has a pressure of only 800-900 PSI full. I think there may a bit of fudge factor in the pressure at filling. If I didn't know exactly what I was doing, and couldn't do it safely, I'd pass on transferring between cylinders.
 
   / Experience refilling argon or 75/25 cylinders yourself?
  • Thread Starter
#36  
If you're anticipating high enough usage, they might adjust your pricing for you.

No volume. SIMPLY want to top off my portable cylinder (in my shop) before heading out with my portable welder. Not afraid to learn how to do it (safely).

I would like to try CO2 sometime, especially if it lasts longer on one small bottle. Do you think there are pics on the web on the same weld process with CO2 and 75/25?
 
   / Experience refilling argon or 75/25 cylinders yourself? #37  
I doubt a welding supply will give any kind of a deal on a 20 cu. ft. cylinder. In reality the tiny cylinders are a PIA! Mix cylinders are usually filled about 16 at a time. There is more labor involved in filling the tiny cylinders. If your usage is up, you wouldn't use a 20 cu. ft. anyway. Gasses are always the most economical, the larger the cylinder. Argon/Co2 mix gas can be up to 2200 PSI just like other high pressure cylinders because it is in gas form.
 
   / Experience refilling argon or 75/25 cylinders yourself? #38  
Sodo, here's yer sign :=)

Mig Welding Gases

Jody's been doing this a LONG time, this is one of the first sites I go to if I have a question... Steve
 
   / Experience refilling argon or 75/25 cylinders yourself?
  • Thread Starter
#39  
Mig Welding Gases
Jody's been doing this a LONG time, this is one of the first sites I go to if I have a question... Steve

Thanks Steve, great site!

He says that an inverter-welder can use CO2 better if the welder has an inductance setting favorable to CO2 gas. He says "it may have a sweet spot". That could be good news as my MultiMatic200 is an inverter,,,, but if it takes experience to find the sweet spot,,,,,, I will need luck then. I just fiddle with speed and voltage until it looks right.

As is my nature I'd like to save some $$ but truth-be-told?.. I need to just throw the thing in the truck and go do my work. I don't weld for pay ----- I weld because I like to build stuff.:cool:

Do you think a MIG (Hobart 140) would weld better on CO2 than fluxcore?
 
   / Experience refilling argon or 75/25 cylinders yourself? #40  
I'm probably not the guy to answer on gas type, or gas vs. fluxcore - haven't used anything but C25 and hardwire since I got my mm211, used it for about 6 months, then found a sweet deal on a complete mm252/dual running gear/2 bottles/30A spool gun for about $100 more than the basic 252 - I've since run about 40 pounds of s6 wire thru the 252. No fluxcore at all yet, considering c02/Lincoln outershield .045 for the heavier fab.

I don't do aluminum, I've set up the 30A for .035 hardwire and use it when the 15' gun won't reach. My LWS has 2 lb. spools of hardwire for $6, so it's not too painful to use compared to 44# spools in the machine.

This strictly from reading, no experience yet - fluxcore = most spatter, think "stick on a roll" - co2 medium, spatter (as you noted) somewhat controllable with a good machine - C25, least spatter, less penetration than co2, and colder. Push reportedly gets better penetration than pull, assuming you NEVER violate the "stay at the front of the puddle" rule.

All that is immaterial if you're gonna "throw it in the truck and go", because unless you also throw in a wind-proof tent, you only have ONE option out in the open unless it's a REALLY calm day. I solved this (temporarily, til next year when I'll get back to a 32x60 addition to the shop) by building a "tent room" in front of my overflowing garage - it's big enough to get either tractor or 3/4 of my backhoe inside, and tarps around the perimeter give me a quiet enough space during all but pretty stormy weather.

Only porosity I've had so far is a couple times when I should have turned the gas valve on BEFORE welding :rolleyes: I've built a heavy set of brush forks, a 6'x8'x2' brush bucket for the Case, beefed up the frame on a heavy duty (up to 1" material) 48" slip roll I found on CL, and a couple other medium sized projects in my "tent room" so far, with no problems doing it this way.

One secret I've found works for me - a toilet paper "wind sock" - I simply hang a 3 foot piece of TP (preferably un-used) :D from the ceiling over my weld bench or project, and if it's moving more than just a lazy wave, I go do something else til the wind's died down enough - with all the tarps around my "man tent", it can be fairly breezy outside and I can still weld - just to be safe, I usually turn up the gas to maybe 25 cfh if the TP is moving at all.

Kinda got off topic a bit maybe - guess the gist of it is "you should ask someone who's been there" :confused3: - I've only been welding since '74 (NOT professionally), and mig only about a year so most guys here are 'way ahead of me... Steve
 

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