Talk to me about oxy LPG.

[soundman]

Now that I have MIG and a plasma cutter I can see the oxy getting less work.

It will probaly only end up doing brazing, a little cutting and maybe some welding.

AND in the interests of cutting bottle rental out of the deal I'm thinking abount shifting the rig across to LPG.

I understand that LPG simply wont produce the heat that acetlene will, the fuel consumption will be a bit higher as will the oxygen consumption.

but do tell.....what are the ins and outs of oxy/LPG and how do you find it compares.

cheers

[steran50]

HI Soundman,
I switched to LPG years ago for that reason of Bottle rental and having a Mig I didn't need to Oxy/Acet weld so much any more. What you heard is correct OXY/LPG doesn't produce the same heat temp as OXY/ACET. According to Wikipedia a common Flame temperature in LPG is 2000 degrees Celcius, OXY/LPG is 2500 degrees celcius and OXY/ACET is 3500 degrees celcius. I didn't think that there was 1000 degrees difference, I thought from memory it was about 650 degrees.

I have been told that you can Weld with OXY/LPG I have tried even with a number 20 tip and no luck at all. I have though Cut, Heated, Brazed and Silver Soldered without any issues. I believe that the Oxygen consumption is higher, but I'm pretty sure that you don't use any more LPG than you would Acetylene. OXY/LPG is a lot harder to light more so outdoors and you need a Flint lighter to light it with the other lighters don't seem to work. I find it harder to get the Flame mixture right, although I haven't searched recently I couldn't find much on the flame mixture in the past. I have had a Heating Tip get a bit hot on me due to not having the flame mixture right, but it didn't cause any problems.

It is good for Heating but it's slower and you have to buy the Heating Tips for OXY/LPG. It's great for Cutting and it actually cuts cleaner. I'm not sure whether or not it can cut the same thickness as OXY/ACET though - I'm sure some googling would find the answer. Setting it up initialy does come at a cost. You will need to Buy a LPG Regulator, Cutting Tips, Heating Tips, Welding tips for brazing and silver soldering ( the oxy/acet welding tips can be modified by using a small drill bit sharpened more to a point to give the tip an inverted cone shape). You can use the same handpiece along with with the same hoses and flashback arrestors.

I hope this give you some insight into what your looking at changing to.

[Karl Robbers]

Oxy LPG is actually better for heavy thicknesses than oxy acetylene. It will easily outperform oxy acetylene for heating as you can run far larger superheating tips due to not being restricted in gas draw off rate as you are with acetylene.
Under $40 for a cylinder of lpg versus over $300 for the equivalent amount of acetylene is a fair motivation too.

[soundman]

I wish I could find my old CIG welding guide from 30 years ago...I'm sure it had all sorts of info in it.

I have heard that people have just used their oxy gear as is unaltered on LPG, with moderate sucess.

From what i understand the regulator output has to be higher for LPG...or "handigas" as CIG used to call it....but an LPG reg is about $40 from "bob the welder" or his competitors.

I'm interested is the difference in the tips.

cheers

[bruce w]

I just cant see why anyone who has a mig would bother with actylene. I have used oxy with lpg for over 30 years and apart from the fact that it has trouble welding sheet and you have to get lpg cutting tips and is a bit harder to light from there on it is all on the plus side. I have been told that you cant get quite as much heat into what you are working on but it has never really been a problem in anything I have done and over the years, seperated masterlinks using heat in dozer track chains, heated bolts nuts bearings that refused to budge and I cant think of anything that would have been better using actylene. I cringe everytime I have to pay the lease on my oxy cyl but at least I know I dont have the same worry with the lpg as I own the cylinder. The other thing is the lpg cylinder seems to last for such a long time as well. Also if you know what you are doing you will generally be able to do a neater thinner cut on steel and brazing solerdering is pretty much the same.

[Legion]

Piggybacking on soundman's thread, I would occasionally like to have heat, mostly for straightening (and maybe for intentional bending one day). At the moment I do dumb things like run a welding bead down an opposite side but this is time consuming, messy, probably less accurate, requires clean up and generally sucks.

Instead of oxy/LPG I'm interested in compressed air/LPG and cut out rental costs altogether. This has been discussed before here but no real-world results compared. If I were to get the Harris 89-3 (knowing nothing about oxy/acetylene or heating in general), would the nominal 130,000 BTU be enough for fixing my warped mistakes?

[Legion]

Well, it looks like I'll answer my own question in time. I just bought a Harris 89-3 that I found secondhand for $100. Now to get a shop compressor.

[TheNutter]

Hi Legion

That looks really interesting, I would be interested to hear how you get on.

Regards

Ian

[soundman]

I think Oxy/LPG is a viable thing, bit LPG/ compressed air is a step too far.

For heating and brazing I doubt that there will be any advantage over a straight LPG air mixing burner.

For cutting I expect it would be far less effective than oxygen, because the steel cutting process relies on rapid oxidisation of the metal.

as far as getting out of the rental thing...speedgas arecurrently offering oxygen in "D" size bottles and moving into "E" size bottles in the new year...on a purchase/ swap basis.

cheers

[Legion]

Yeah, I have no idea. There was next to nothing about them on the internet. But I only want it for straightening and for $100 it's a gamble I was willing to take.

[Karl Robbers]

Cutting is out of the question as you realise, but as a light duty heating torch it may not be too bad other than not being as portable as oxy/fuel gas.
A quick comparison of specs between Oxy Acetylene, Oxy LPG and Compressed air/LPG torches heating capabilities.
In the heating performance stakes, we have in third place, the Harris 89-3 with an output of 130,000 BTU, next comes Oxy Acetylene with a respectable 204,000 BTU from a 12X12 heating tip and in first place, the clear winner, Oxy LPG with a massive 900,000 BTU from an H5 super heating barrel.
I would estimate the heating performance of the 89-3 as somewhere around that of a number 15 oxy acetylene cutting tip, but not as focused in its flame.

[soundman]

I'mmm realy looking at compressed air / LPG in the "OH why bother catagory".

for general purpose light heating, just plain LPG and a standard air mixing tip will probably do nearly as well as running a mixing blowpipe and compressed air......I may give it a go for $@#!ts & giggles though.

Outright heating volume is one issue and on LPG its a matter of how big your burner is and if your reg will support it.

BUT, in the temperature stakes and temperatures that may be required for brazing and silver soldering......I'd expect adding oxygen will have to lift the game considerably.

Anyway the die is cast...the acettelene cylinder is nearly empty......I'll find a reason to use it and It'll be on its way.......the rented oxygen cylinder wont be far behind it.

I think I'll cough up a massive $40 for a 9Kg LPG and $130 ish for a trade flame kit for the light heating & I'll have a big think as to which way to go with the oxygen.

cheers

[Karl Robbers]

I'mmm realy looking at compressed air / LPG in the "OH why bother catagory".

for general purpose light heating, just plain LPG and a standard air mixing tip will probably do nearly as well as running a mixing blowpipe and compressed air......I may give it a go for $@#!ts & giggles though.

Outright heating volume is one issue and on LPG its a matter of how big your burner is and if your reg will support it.

BUT, in the temperature stakes and temperatures that may be required for brazing and silver soldering......I'd expect adding oxygen will have to lift the game considerably.

Anyway the die is cast...the acettelene cylinder is nearly empty......I'll find a reason to use it and It'll be on its way.......the rented oxygen cylinder wont be far behind it.

I think I'll cough up a massive $40 for a 9Kg LPG and $130 ish for a trade flame kit for the light heating & I'll have a big think as to which way to go with the oxygen.

cheers

I tend to agree with you. Compressed air/LPG strikes me as a strange process. While it most likely provides higher temperatures than Air/LPG, the gains wouldn't be that great. I would think its forte would be soft soldering large components and possibly light duty pre heating.
It may be an interesting option for a furnace though.
I ditched acetylene some time ago and run oxy/LPG and haven't looked back. There will always be a place for acetylene in industry because there are some environments where LPG is not allowed due to being heavier than air, but few who swap to Oxy/LPG go back to acetylene from what I've seen.
I'll be interested to see how Legion's compressed air/LPG setup works.

[soundman]

another thing that I have come across that is apparntly good for cutting is OXY/ PETROL...but the rig aint cheap like $700 for a rig, pluss the oxy cylinder & reg.

But I supose it still cheaper than the cost of either owning or rebting an aceteyene cylinder and the fuel is a hell of a lot cheaper.

cheers

[Grahame Collins]

Guys,

Just be aware that if you commit to Oxy LPG that you cannot weld steel .

The steel melting point is well over the 2500°C provided by the Oxy/LPG flame.

I have looked at the local Mackay swap and go cylinder thing but its only available for oxy /acetylene so far ,no sheilding gases as yet.

Grahame