propane or acetylene ?

   / propane or acetylene ? #1  
R

Renze

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I have decided to bite the bullet and buy a torch set:

I could get a plasma from 350 euro onwards, but the dealer i regularly buy stuff from, offered me a small professional quality one for 1750 euro, he said he wont sell the cheap ones because he has to attach his good name to anything he sells.
With O/A or O/propane i can also heat, and weld if required.

Propane is cheaper, but cuts rougher ? Is the price difference that big between propane and acetylene consumables ? Can you cut both with one torch ?
 
   / propane or acetylene ? #2  
From Wikipedia

"
A propane torch is a tool for burning the flammable gas propane. The maximum adiabatic flame temperature a propane torch can achieve with air is 2268 Kelvin (1995 °C/3623 °F). Some propane torches are also used with a tank of pure oxygen to achieve a flame temperature nearing 3095 Kelvin (2820 °C/5110 °F).
The temperature in these flames is lower due to not total oxygen gain of combustion, heat loss in combustion, oxygen quantity etc.
Propane torches are frequently employed to solder copper water pipes. It can also be used for some low temperature welding applications, as well as for brazing dissimilar metals together.

"Acetylene when combined with oxygen burns at a temperature of 3200 °C to 3500 °C (5800 °F to 6300 °F), highest among commonly used gaseous fuels. As a fuel acetylene's primary disadvantage, in comparison to other fuels, is high cost.""

So as you can see acetylene burns considerably hotter which can be important in both cutting and welding.

Andy
 
   / propane or acetylene ?
  • Thread Starter
#3  
But will propane cut ?
Max. flame temperature isnt important when heating, only when cutting.
 
   / propane or acetylene ? #4  
Yes, propane will cut just fine. Some people prefer it to acetylene. It does take a little longer to start the cut, though.

When I was taking welding classes on the gas welder, we never even bothered with Oxy-Acetylene. We just used Oxy-Propane. I'm sure cost was an issue.

If you are trying to weld with propane as well, you may have to adjust your tip sizes. I've heard it isn't good to switch between propane and acetylene - bad for the hoses. That was long after I've been switching back and forth, though.
 
   / propane or acetylene ? #5  
First of all it isn't the propane, or acetylene that does the cutting, it is the high pressure oxygen. You can often turn off the burning gas once you are cutting and just use the oxygen (if you are steady). The purpose of the burning gas is get the burning process started just like using a match to start a campfire. Once you have the wood burning all you need is wood and oxygen, you don't need the match. Once you get the steel burning with the torch all you need to add is oxygen.

If you are going to get a torch for cutting I would get the oxy/act setup because of the higher burning temperature as previously mentioned.

I have seen cutting torch setups for propane, but due to the lower temperature you would limited as to what you could cut and it would take longer to raise the metal to the melting point. I am not sure if the propane torch could also be used for acetylene. Why would you want to use a propane setup in any event?

Plasma cutters are great, but much more expensive for a given depth of cut. I would have both if I did a lot of cutting, but I scrape by with a oxy/act setup and a guide holder.
 
   / propane or acetylene ? #6  
I have propane, my son who was working at Scrapping for a number of years soon switched to propane, as well.

the propane in fuel cost is less, it heats good, and one can braze with it, (just need the correct tip, (my son just went the cutting torch route, I bought him to industrial Smith cutting torches off of Ebay brand new, and did not go the interchangeable ends and body, but 98% of what I do is cutting,

YOU CAN NOT WELD with it, you need acetylene to weld with, (steel), but if you have a wire feed I doubt if you will ever miss that possibility,

I think Propane is safer to handle as it will not self ignite if over 15 pounds of pressure, you do not have to be concerned about the with draw rate out of the cylinder, or if the cylinder was on it side,

if you have a propane tank on your property one can add a wet leg and fill your own tanks, (using the bleed off method).
(90% of the propane my son used he never even had to pay for as the farmer would normally let him just refill his tanks out of his farm tank),

I like the Smith set up, yes the hose is different for propane "T" rated, but can be used for both propane or acetylene, where the hose that comes with most sets should only be used for acetylene. to switch from one gas to the other you just change the cutting tip, to the correct one for the fuel your using,

I have both fuels but have all the torches (we have 4 torch sets) on propane, (the tanks are much cheaper as well) a BBQ tank, you can get a special tank that is small diameter and taller but the BBQ tanks work just as well.
 
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   / propane or acetylene ? #7  
As far as the heat issue, yes the propane is cooler,

but one thing that throws people off is where the heat is in the flame.

On acetylene the heat is in the flame
On propane it is at the tip or just off the tip of the flame

And if your only experienced with acetylene and using propane you can be disappointed,

but if you hold the tip a little further away there is not that much difference in the actual heat (on propane I oxidize the flame a touch as well and that makes it hotter as well),

below is a very good read about the two flames and cutting with the gasses,

Andys Place, Propane vs Acetylene Cutting
 
   / propane or acetylene ? #8  
BHD said:
As far as the heat issue, yes the propane is cooler,

but one thing that throws people off is where the heat is in the flame.

On acetylene the heat is in the flame
On propane it is at the tip or just off the tip of the flame

And if your only experienced with acetylene and using propane you can be disappointed,

but if you hold the tip a little further away there is not that much difference in the actual heat (on propane I oxidize the flame a touch as well and that makes it hotter as well),

below is a very good read about the two flames and cutting with the gasses,

Andys Place, Propane vs Acetylene Cutting
Click to expand...

Interesting article. I use my torch for welding also, so I guess I will stick with what I have, but for anyone just cutting, propane looks like a good alternative.
 
   / propane or acetylene ? #9  
   / propane or acetylene ?
  • Thread Starter
#10  
interesting reading!
So the peak temperature of the propane is lower, but there is more energy in a cubic foot, or liter.

The propane doesnt create its own Co2 shield gas so you cant weld with it ? Co2 will occur when something is burning, and thats not the intention when welding...
So when you arent used to anything specific, one can learn torching practice with either gas... In welding class at technical school, they learned us that you have to weld with the tip of the white flame. But thats 10 years ago so i can easily change habits ;)

even if i cant weld with it, i could at least pre-heat heavier steel which are a bit much for my 210A mig.

used sets are more readily available for acetylene, propane i'd have to buy new. is the cost of combustion gas that much lower ?
 
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