Thinking about Oxy-Propane

[JHCC]

Thanks! I'm planning to get a 0-3-GPN and maybe a 2-3-GPN as well; Cyberweld has them for $14.50 each.

I asked them what flashback arrestor they'd recommend to go with the Medalist, since the included torch has already has built-in check valves. I'll let you know when/if they answer.

[JHCC]

Another (probably basic) question: which is better for spot heating -- the rosebud or a cutting torch without the oxygen boost? I'm thinking of things like rivets and localized bends.

[Frosty]

Brazing tip for rivets under say 3/8. Rosebud for bending say 1/2" and larger. Cutting torch is for cutting, they're not mini rosebuds. The oxy jet orifice doesn't make a flame, it makes a cold spot in the center of the ring shape preheat flame. They WILL work, just not the better tool.

Frosty The Lucky.

[JHCC]

I hear you, Frosty, but I'm trying to follow up on what teenylittlemetalguy said above:

On 3/4/2021 at 1:54 PM, teenylittlemetalguy said:

I am completely sold on it for rivets, worth the money just for that alone.  I have been using the cutting head for brazing and while it works fine, it is heavy and clunky. 

Since the Medalist doesn't have brazing tips as such.

[teenylittlemetalguy]

On 3/10/2021 at 10:32 AM, JHCC said:

Thanks! I'm planning to get a 0-3-GPN and maybe a 2-3-GPN as well; Cyberweld has them for $14.50 each.

I asked them what flashback arrestor they'd recommend to go with the Medalist, since the included torch has already has built-in check valves. I'll let you know when/if they answer.

I would really appreciate that JHCC. 

I think the real answer for what head to use is going to depend on the size of your work. The heat area is pretty small with a cutting torch. I used the 1-3-GPN for 3/8 rivet and it was plenty fast enough for me, I wouldn't pay for a tiny rosebud to do something like that.  If you are looking to isolate heat on a bend then a rosebud is going to do much better for you. There is one in the kit I have not even used yet. Let me try it in the morning and let you know how good it is on larger stock. 

[JHCC]

Thank you! 

3/8" is about the size of rivet I had in mind (give or take a bit), so that's good to know.

I was doing some further research on the Cyberweld website and discovered that the WH411C handle that comes with the Medalist accepts W-series welding tips. Don't know if you can burn propane in one, though, and not sure I want to spend the extra $50 to find out.

[JHCC]

30 minutes ago, teenylittlemetalguy said:

On 3/10/2021 at 2:32 PM, JHCC said:

I asked them what flashback arrestor they'd recommend to go with the Medalist, since the included torch has already has built-in check valves. I'll let you know when/if they answer.

I would really appreciate that JHCC. 

Just spoke with Cyberweld, and they said any flashback arrestor will work fine. Just pick whether you want torch-mounted or regulator-mounted, and you're good to go.

Interestingly, there was an IFI thread back in 2019 that had the following interesting observation about flashback arrestors and propane from member Brian D:

Quote

I would not worry about it much with Propane (LPG). From what I have learned, propane has a pretty small mixture percentage band where it can burn. (from about 2% to 10% gas percentage to oxygen) This small mixture percentage means that the flame can and will not burn straight from the hose or follow the gas up the hose. It must be mixed with air at the right percentage to burn at all, if it is too rich or lean, it will extinguish itself.

However, I don't know how accurate this is or whether it's just a reasonable-sounding justification for doing something stupid. I await the input of those with more knowledge and experience!

[ThomasPowers]

The big problem is with Acetylene which can "exothermically disassociate" WITHOUT the presence of Oxygen and so can actually explode in the tank if their isn't an arrestor at the tank/regulator.  Running over an acetylene hose with a forklift was the example we were given. 

Now in odd situations you might leak high pressure O2 into the propane line but extremely unlikely you could ever get enough in the tank to go boom.

Acetylene just doesn't want to be on the earth with us!

[JHCC]

1 hour ago, ThomasPowers said:

you might leak high pressure O2 into the propane line

Wouldn’t the check valve prevent that?

[ThomasPowers]

That's why it's unlikely.

[Frosty]

You've never tried my torch Tristan? My #2 brazing tip will melt a 3/8" rivet in a few seconds and it weighs a fraction what the cutting head weighs.

Next time you're out we'll have to fire it up. The downside is the set cost me more than $700 in the early 80s when you could buy a compete Victor oxy acet set W/ regulators and hoses for under $150.

Frosty The Lucky.

[JHCC]

Frosty, is that a brazing tip made specifically for propane?

[Frosty]

The whole torch is, the: regulators, handle, and tips. The propane "regulator" is a meter and delivers propane according to the oxygen flow, not by pressure. The propane pressure is set and can't be changed without taking the regulator apart. There is a mixing tube between handle and interchangeable brazing tips. I haven't looked in quite a while but I believe I have 3 tips, #1,#2 and #3 I don't think I've ever used the #3. I hardly ever braze. 

They get more than hot enough to weld, unfortunately the flame velocity is so high it literally blows the melted steel out of the puddle so it's pretty useless for gas welding. I don't care what the maker says. That's okay, I have a wire feed and stick welders.

Frosty The Lucky.

[JHCC]

I'm not particularly concerned about welding either, since I have the borrowed wire welder and am looking forward to learning how to use the stick welder once I get the 230v outlet rewired.  I'm just thinking about the best way to use the oxy-propane for spot heating for rivets and the like.

[Frosty]

The only oxy propane torches I have any experience with are conversion tips, say 1985 and earlier, that were pretty poor performers and serious oxy hogs. I can't say anything about new conversion tips.

I know my All States oxy propane torch well. I use it for spot heating and occasionally cutting with the rare spot of brazing and silver soldering. I have welded aluminum with it with my tiniest tip. That was kind of weird but went well and was as strong as the parent metal but I was just trying out the sample rods the welding store guy gave me.

A LOT of people use the cutting head as a heater. Just because my rig has that covered without using the cutter doesn't mean it isn't a good option for others.

Frosty The Lucky.

[JHCC]

Well, we shall see. 

[teenylittlemetalguy]

19 hours ago, Frosty said:

You've never tried my torch Tristan? My #2 brazing tip will melt a 3/8" rivet in a few seconds and it weighs a fraction what the cutting head weighs.

Never had the chance. I am sure a brazing tip would be better. If I had a big brazing tip I would use it. 

For the price I'm pretty happy with the performance I have. 

On 3/11/2021 at 2:50 PM, ThomasPowers said:

That's why it's unlikely.

Thank you! I feel a lot better about it all.

On 3/11/2021 at 11:56 AM, JHCC said:

 

3/8" is about the size of rivet I had in mind (give or take a bit), so that's good to know.

Sorry it took me all day. The torch comes with a. N8 rosebud tip. Really surprised me with the speed. It took a cold 5/8" round bar up to a nice bending range in about 30 seconds.  And the heated area was only about 1-1/4" wide. It's going to be super handy for me.

I would be really careful about triple checking any accessories before  buying them. It's all a giant cluster of misinformation out there. 

Thanks the info on the flashback arrestors. I will read up some more on that.

[Leather Bill]

2 hours ago, teenylittlemetalguy said:

I would be really careful about triple checking any accessories before  buying them. It's all a giant cluster of misinformation out there. 

Thanks the info on the flashback arrestors. I will read up some more on that.

Giant cluster is right,a point I attempted to make earlier but I see it didn't gel.  Just any old flash arrester isn't suitable for propane.  It must say''FUEL'' on it w'hich means all fuels.  If it says ''acetylene'' that is the ONLY gas it's rated for.  There is no such thing as propane welding tips but heating tips that look like acetylene welding tips( but have recess same as cutting tips) are available and are exellent for brazing and pinpoint spot heating. Scarace but can be found.  Another system look's similar to rosebud and has interchangable heads.  AFIK neither is offered by OEM mgrs but can be had for most brands.  Another system replaces handle with an air/propane handle.   Now you know why so many folks braze and heat with cutting torches. 

[teenylittlemetalguy]

4 minutes ago, Leather Bill said:

heating tips that look like acetylene welding tips( but have recess same as cutting tips) are available and are exellent for brazing and pinpoint spot heating. 

Yeah, victor makes one with different tip sizes you can change out and it fits my torch, they are pretty spendy though so I will likely outfit my other small torch for brazing. 

[Leather Bill]

15 minutes ago, teenylittlemetalguy said:

Yeah, victor makes one with different tip sizes you can change out and it fits my torch, they are pretty spendy though so I will likely outfit my other small torch for brazing. 

For occasional small jobs,a B tank and acetylene tip is quick and cost effective.  Some claim you shouldnt bonce back and forth but never explain why so I've done it for years.

[teenylittlemetalguy]

11 hours ago, Leather Bill said:

For occasional small jobs,a B tank and acetylene tip is quick and cost effective. 

I have a little B tank of acetylene that I have used as sparingly as possible over the years. I think it will probably go away now that I see the power of oxy/propane. 

[Frosty]

You don't switch between propane and other fuel gasses because propane is very chemically reactive and attacks rubbers and plastics not formulated to be resistant. It also leaves residue that can form unfortunate compounds on contact with other reactive chemicals like flammable gasses. Acetylene is C2H2 and is extremely unstable both physically and chemically, it's extremely unwise to mix acet components with other fuel gasses, especially propane. 

Flash back arrestors are much more necessary with acetylene than other fuel gasses as it will disassociate into C2 and H2 exothermically with shock or pressure, with secondary fuel air explosion when the super heated gas mix escapes into ambient atmosphere. The red line at 15psig on acet regulators isn't there by accident, there's a little margin but it's dangerous territory. You hear the stories about maxed or over pressured acetylene hoses exploding when dropped from a height or slapped on the ground, run over or just too close to heat. Acetylene was the single most covered safety issue in metal shop classes and trade school classes next to PPE.

Frosty The Lucky.

[Irondragon Forge ClayWorks]

Funny I have used A/O for over 50 years with nary an issue. Of course one has to be cautious when using any flame producing equipment. Most accidents I have been aware of were due to carelessness.

[Frosty]

The closest to an accident I've seen personally in about the same length of time, was when some idjit left the torch burning and was turning off the tank valves after opening the regulators all the way. Happily all that happened was a back fire that didn't quite melt the cutting torch. The welding supplier replaced it, said it wasn't worth rebuilding. The guy KNEW you were supposed to bleed the hoses off and thought of a shortcut. 

You are right though, OA torch isn't too dangerous unless abused or something unforeseen happens and that can happen to anything. In many ways, oxy prop is more dangerous, an acetylene leak will rise and dissipate where a propane leak will settle into low points and can become an explosion or fire hazard. Everything we do and use is inherently dangerous and so long as a person isn't so preoccupied with safety s/he misses something else, safety is a good thing. Knowing the potential hazards is a pretty important part of knowing what to watch for, no?

Frosty The Lucky.

 

[Irondragon Forge ClayWorks]

My wife has a nifty small acetylene/air torch set that she uses with jewelry work and soldering/brazing. It will get up to 4770°F. I've used it to set hot rivets when I didn't feel like firing up the A/O setup.