Thread: Converting to LPG and CO2

Not to sure about the LPG stuff, but I'm just about to convert over from Argoshield to CO2.

I've recently finished all my light panel work and just got the bill for Argoshield cylinder rental in the mail the other day ($159.39), which I won't renew. I previously did some testing with a mates home brew Co2 and the results are here, so I know what to expect.

When I was doing my testing, I did not find a need for a heater, so when I purchase my gear, I won't bother with one. I priced up a 6kg cylinder and a cheap reg and I can get them for about $330 delivered.

I work in the retail supplies sector of the industry and there is still a lot of guys out there that prefer LPG especially for large civil project work. (don't ask me why I haven't been in the industry very long.) But at a guess it would be mainly due to the ease of portabily. I do know that you need a different regulator, hose, torch and there is a variety of tips and nozz specifically for LPG.

Traps for young players there are ,

You might do the research on the BTU value of Acetylene against LPG and knowing that the rate Oxygen consumption when using Actylene.I recall doing this same exercise several years ago and the overall $ results aren't that different.

To cut through the tech speak you need to use more oxygen when using LPG to achieve the same (Heat) results when using Oxy Acetylene .

Volume against volume the acetylene is the most efficient heating (and therefore heating for cutting gas) on the planet.

You cannot ( fusion ) weld using a Oxy LPG set up as it takes (from memory OK!) about 3200C to melt M/steel to weld it. All you can achieve with LPG is around 2800C -close but no Kewpie doll (or welding for that matter)

However Oxy /LPG cutting the ignition temperature is 915C.It will cut but not as fast or with the quality of cut finish that acetylene provides.

Mapp gas is a touch better at heating than LPG ,I did look it up at one stage but have forgotten by how much.

For the Co2 VS Argosheild comment I won't make one.

Does this help?
Grahame

Originally Posted by Vernonv

... I priced up a 6kg cylinder and a cheap reg and I can get them for about $330 delivered.

not this cylinder is it???

New Steel 6Kg CO2 Bottle Cylinder Filled with CO2 gas (eBay item 200615131057 end time 02-Jul-11 11:50:54 AEST) : Home

I just found this the other day but was wondering if anyone has got one before I jump in.

I did the propane trip fifteen years ago and purchased harris torches,tips,gauge's etc and was quite happy with cutting and to some extent heating and the non existent rental from the boc thieves on my bottles of lpg.HOWEVER,the massive increase in oxygen consumption did not justify the conversion,by my estimate,i increased my oxy usage by up to 6 times.i would say for occasinal use at home it would be ok but i wont go back to it for industrial usage.hope its of some use,cheers danny

so the consensus is it's not worth it to swap to lpg i go through three d size acetylene and two e size oxygen cylinders in a year but it's getting to the point were i cannot afford the rental for three cylinders. all i do is cutting and heating.

Originally Posted by gallegos

not this cylinder is it???

New Steel 6Kg CO2 Bottle Cylinder Filled with CO2 gas (eBay item 200615131057 end time 02-Jul-11 11:50:54 AEST) : Home

I just found this the other day but was wondering if anyone has got one before I jump in.

Yep that's the one. Just waiting on approval from the finance minister before I purchase. The cylinder I borrowed from a friend when I did my testing was exactly like that one, although it wasn't purchased through that guy.

Wow, I didn't know about the extra oxygen usage. Lucky I asked, thanks. I have got quite a bit of money invested in acet gear. Heaps of regs, countless cutting and gouging tips, hoses etc. Maybe I'll just stick with it.

Oxy lpg excells at heavy plate cutting, its main industrial use and has advantages when preheating heavy sections for welding. For general handyman use you will not like it as it produces inferior cuts on thinner sections, (due to the less focussed flame compared to Acetylene) and as has already been posted, gobbles oxygen at an alarming rate.
As far as welding with CO2, two words.

DO IT

Argoshield is the most overated, overpriced and uneccesary gas for most people. Even panel work can be done by a skilled operator. Its penetration profile is superior, several of the welds properties are higher than that produced by argon mixes, it handles galvanised and dirty surfaces better and is far cheaper, all while producing less porosity.

Originally Posted by Karl Robbers

As far as welding with CO2,

I've been considering trying CO2 for MIG - I've been welding with flux-cored as it produces good quality welds with the material I work with - mostly 1.6 - 5mm section, a lot of it Duragal.

The catch seems to be the regulator - getting a CO2 bottle seems pretty straight forward, however the connections seem to be incompatiable to those on the regulator.

Argon/CO2 regulators have a male fitting, while beer gas type CO2 cylinders have a male fitting too - is there a readily available regulator to fit these cylinders, or is it a matter of doing a bit of plumbing?

Re LPG,

If my fading memory of chemistry serves me correctly then we can determine usage by the complete combustion equations for the two gasses. The problem with precision is that LPG is a mix of propane and butane and I dont know the quantities. Anyway, the complete combustion equations are:

Propane (C3H8). C3H8 + 5O2 = 3Co2 + 4H20
Butane (C4H10). 2C4H10 + 13O2 = 8C02 + 10H20
Acetylene (H2C2). 2H2C2 + 502 = 4 Co2 + 2 H20

So, to burn a molecule of propane you need 5 of oxygen and to burn a molecule of butane you need 5.5 molecules of oxygen. However to burn a molecule of Acetylene you only need 2.5 molecules of oxygen, half as much.

There are probably other factors at play but this gives you an indication.

Re Co2 for shielding....can this be used for TIG welding or only MIG?

I am not totally familiar with beergas cylinder fittings, but there are regulators available to fit welding grade CO2 bottles, what i have always done is to use an adaptor between an argon regulator and the CO2 bottle. Any good welding supply company should be able to source one of these and don't be tricked into believing that you need a gas heater- you don't.
While on the subject of CO2 for welding, remember that your flow rate needs to increase from 8lpm that you would run with Argon mix gas to around 10lpm and your wirefeed settings will be less at the same voltage setting. CO2 is suitable for carbon steel, not Stainless, (it will cause carbide precipitation). Actually on the subject of carbide precipitation, has anyone seen the HenRob welding torch demonstrated recently? I often used to see them at rural and trade shows where they would proclaim that their oxy acetylene welding torch could weld stainless steel with no flux, using a CARBURISING FLAME. Absolute nonsense, while it may weld, the weld would be of very poor quality and would suffer intergranular corrosion due to the excess carbon. I seem to remember that it was a husband and wife team doing the demonstrations, that particular lady had one of the steadiest hands I have ever seen.
Regarding CO2 for TIG welding, unfortunately, no go. Argon is the only real choice in Australia, as Helium is far too expensive.

Hmm...

If you have both TIG and MIG, you get clobbered for two bottles. Argon and Argon / Co2

Wonder if you could just get the Argon off the thieves for the TIG and buy a bottle of Co2... and somehow run a mixer valve to create your Argon Co2 mix for MIG?

Is this feasible or even possible?

Where theres a will theres a way!

Not sure how youd ensure even mixing but it wouldnt be hard to put a splitter in your line and feed C02 and Argon into your Mig.