new disposable welding gas cylinders - nearly empty?

Summary: Two new Argon/CO2 disposable cylinders seem to be nearly empty. Are they?

Details: I purchased (online) two of the small disposable cylinders of welding gas (boron/co2 mix 110l) and put one in my old Clarke 100E Mk 2 mig welder the day they arrived. I turned the regulator up to about 3 which is usually not far out and tried to weld - no gas. I had to turn the regulator up to the maximum (6) to get a low hiss.

A part used pure CO2 cylinder I've had for several years works fine at position 3 on the regulator.

By way of investigation, I weighed both new cylinders and they were a good bit lighter than the part used CO2 one. I screwed the regulator onto the other new one and also had to turn it up to almost 6 to get an audible hiss (direct from regulator - ie not connected to plastic tube).

I told the retailer that I suspected they'd been leaking or not filled properly and they promptly sent me two replacements FOC. Those two are both exactly the same - ie lighter in weight than the old CO2 cylinder and much lower pressure - would require the regulator at max to weld.

Weights:

Old part used cylinder of CO2:

1518 grams

New Argon/CO2 cylinders:

1) 1393 grams 2) 1367 grams 3) 1364 grams 4) 1388 grams

Can I expect CO2/Argon mix to be at a similar pressure to pure CO2 and am I right in assuming faulty goods or is there another explanation I haven't thought of?

Reply to
Andrew19231
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Does the manufacturer / seller provide a description of the product, including the weight of gas? If not, why did you buy from them?

Reply to
Graham J

Perhaps they've put helium in 'em. ;-)

Reply to
Cursitor Doom

Move on to a real cylinder, with a real regulator, you can buy them online or at many car shops. These are filled to a real pressure (2,ooo psi) and you can see on the regulator that pressure.

Reply to
MrCheerful

Max pressure for pure CO2 is 800 psi (it liquifies), you can get 2000 psi for Argon with a few percent CO2 of course.

Reply to
newshound

My Argoshield 'light' bottle is showing 2000 psi, it came filled to

230bar which is about 3400
Reply to
MrCheerful

I was just flagging the point in case the OP looked at some real bottles and wondered if a (pure) CO2 bottle showing 800 was another fault. IIRC Argon welding mix is 5% or less CO2, sometimes 1% or so oxygen. So no problem supplying it at 3400 psi.

Reply to
newshound

Sounds like he intends to move up to a mix in any case. Oddly enough I have never had CO2, so I had not realised the pressure limitation (or kept it in memory if I ever knew it). I used it at night school, but the gas bottles were in a completely separate area, off limits, to the students.

Reply to
MrCheerful

Density and state.

Argon gas 1.661 kg/m3 at 1bar 20°C won't become fluid under pressure

CO2 gas 1.815 Kg/m3 at 1bar 20°C CO2 fluid 780.84 Kg/m3 at 58 bar 20°C

Reply to
Peter Hill

The point being you get more mass of gas in a bottle if it liquefies? Those argon disposables are very expensive for the mig but the monthly cost of argoshield size Y is too much for my hobby use and I gave up the portapac oxyacetylene ten years ago.

On a related note, can CO2 be used for TIG on mild steel sheet or is argon necessary to protect the electrode?

AJH

Reply to
news

You can get rental free cylinders nowadays, just pay a deposit and the cost of the gas plus delivery if needed.such as this (first google):

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You must have pure argon for tig.

Reply to
MrCheerful

Cheers for that.

AJH

Reply to
news

For both disposables and refillables, the pressure they are filled to is determined by the strength of the bottle.

This is true, that is why propane and butane cylinders are very efficient ways of storing energy for heating, and why quite small CO2 cylinders are useful as fire extinguishers (and for pumping large volumes of beer).

But with Argon + 5% CO2 in a 200 bar cylinder, the partial pressure of CO2 is only 10 bar, at which pressure it is a gas at normal temperatures.

Reply to
newshound

These disposables say 110 bar on them which is not far short of 2K psi and much higher than CO2. They are slightly more expensive for ~ double quantity of gas (said to have 110L in them instead of 60L) so I thought I'd give them a go.

The regulator - which came with the welder many years ago has been a good one, but it turns out that although still fine for CO2, it was the problem and not the cylinders. At max setting it was not opening up quite enough to allow a decent flow. Conversely to what I thought I remembered, a higher pressure gas needs a higher setting on the dial, not a lower one so I was wrong in assuming that low flow at max dial setting meant lower pressure. I should have looked up a diagram of how they work. I find it is easy to feel the difference in pressure, by manually depressing the valve centre of each cylinder - that takes much more force on the argon/co2 mix than the pure CO2.

I don't use the welder much but the "real" cylinders your suggest - are a possibility so thanks for that info. I didn't know they were available without annual rental.

Reply to
Andrew19231

The big cylinders are actually 230 bar when refilled.

It is usual to use a flow meter when using tig, that would have shown up the problem straight away.

There are several independent, non rental, gas suppliers, but afaik only BOC sell acetylene.

I dropped my BOC contracts years ago, I had a portapak, big oxy acetylenes, a big argoshield, and a small argon, the costs did not spiral upwards, they exploded!

Reply to
MrCheerful

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