acetylene vs propane

[Doug Fattic]

I'm just going to add a few more details to what has already been written using propane with an oxygen concentrator for brazing. Now that I've had this setup for about a half year I can give some more refined observations. I've been amazed at how much longer and cheaper my BBQ bottle of propane lasts compared to acetylene. I have a fairly big acetylene tank that costs me $35 to refill. During those 6 months I've taught 3 classes with 3 students in each class (with Herbie as my assistant). 5 students have used propane and the other 4 acetylene to practice and build their frames. We gave our multiple demonstrations in propane. I've also done my own work between classes with propane. I've had to change acetylene tanks but my propane tank (which costs me $18 to refill) is only down less than half way.

I found that turning the propane line pressure down to 2 psi (instead of 4 or 5 previously) makes it easier to keep the flame attached to the tip when the propane is turned up before oxygen is added. I still seem to get plenty of oomph in the flame at that line pressure after the final adjustments with oxygen.

Ordinarily lighting a propane flame is a 2 step process to keep it from separating from the tip or blowing out. Only a small amount of propane can be initially turned on when lighting the flame. After it is lit, it can only be turned up so far before it separates. I start to add oxygen before the flame separates. I watch the end of the inner tip until the very end starts to turn a bit yellow/orange. That is about the right adjustment for propane and then I can turn up the oxygen to match. Usually the right gas balance is when the flame starts to turn from a greenish color to a more bluish. You can get a feel for where a neutral flame is by adjusting the oxygen back and forth and watching the flame color change a little from a greenish hue to a bluish one. You've got it right when it is in the middle of those colors.

As I learned from mattsummers post, it is not possible to tell how much propane is left in the tank by looking at the tank pressure gauge. I went to Lowe's to find a gauge that indicates how much propane is left in the tank (I tried at the local hardware store first). It cost me about $12. I attached this new gauge to the propane tank and my Victor regulator to the gauge mount. They both have 510 G fittings. It takes some seconds for the gas to get through the gauge before the regulator gauges pop open.

I will mention again that when I am using the oxygen concentrator, I have to turn it on a few minutes in advance so its internal bladder can fill and purge the line so only oxygen is coming out. I have to open the knob on the torch to let the oxygen pass through or the machine will beep saying Grandma isn't getting air.

Doug

[suhacycles]

Great stuff as usual, Doug!

Question(s): Would you be able to take photos of the flames, perhaps one that was just lit and the other of what it would ideally look like with O2?

[Will Neide]

Anybody using a rosebud with your set-up? I feel like I need more heat for the lugs. I'm just using a #2 tip right now, and I can make it work, but seems like I need more heat.

[Doug Fattic]

Anybody using a rosebud with your set-up? I feel like I need more heat for the lugs. I'm just using a #2 tip right now, and I can make it work, but seems like I need more heat.

You might want to try a 3-TEN or even 4-TEN tip if you feel like you need more heat. I use a #3 on lugs myself. The problem I'd have with a rosebud is that I couldn't get pinpoint heat control to clean just the shorelines of any extra silver peeking out beyond the lug.

Bigger/smaller tip choice is an interesting dilemma – especially for beginners (the group for which my comments are focused). The bigger the flame, the broader and more general the heat application is. The good news is that it takes less thought and effort to evenly cover the joint area. By the way the most common rookie mistake is not heating a joint evenly so a bigger tip helps with that. They tend to get into a flame pattern like in a groove where some areas are over heated and others under heated. But the bad news is that they have to react more quickly to prevent scorching. Most beginners tend to realize a joint is too hot too late. The middle ground of requiring a more precise and choreographed flame pattern with a smaller tip is balanced against the faster reactions required with a bigger tip is different for each person. The more experienced a builder, the bigger tip they will want to use so they an get in and out faster with a smaller HAZ (heat affected zone).

[Will Neide]

You might want to try a 3-TEN or even 4-TEN tip if you feel like you need more heat. I use a #3 on lugs myself. The problem I'd have with a rosebud is that I couldn't get pinpoint heat control to clean just the shorelines of any extra silver peeking out beyond the lug.

Bigger/smaller tip choice is an interesting dilemma – especially for beginners (the group for which my comments are focused). The bigger the flame, the broader and more general the heat application is. The good news is that it takes less thought and effort to evenly cover the joint area. By the way the most common rookie mistake is not heating a joint evenly so a bigger tip helps with that. They tend to get into a flame pattern like in a groove where some areas are over heated and others under heated. But the bad news is that they have to react more quickly to prevent scorching. Most beginners tend to realize a joint is too hot too late. The middle ground of requiring a more precise and choreographed flame pattern with a smaller tip is balanced against the faster reactions required with a bigger tip is different for each person. The more experienced a builder, the bigger tip they will want to use so they an get in and out faster with a smaller HAZ (heat affected zone).

Thanks Doug! I just received my 3-TEN and have only played with it a little bit, BUT it is a big difference. Even just doing little braze-ons and small fillets seemed to go easier. Things heated up much quicker and smoother and allowed me to get in and get out.

For some reason I received a 1-TEN as well, didn't think I ordered it, but I did try it and it was too weak for bronze. Just took too much time. Might be ok for silver though.

[Alistair]

Thanks Doug! I just received my 3-TEN and have only played with it a little bit, BUT it is a big difference.

I need to go back and re-read this thread from the beginning. I know that Doug listed sources for different torches and tips.

Before I do that can anyone tell me the preferred source for the UN-J mixer tube and the #-TEN tips at the moment? Seems like most welding supply houses don't carry these.

Thanks,

Alistair.

[dsaul]

I had a hard time finding the Victor UN-J mixer too. I ended up going with the Gentec mixer and tip from Torchtools. They have combos that have the mixer with the tip already attached. I think mine is the Gentec 17-3, which is the equivalent to the UN-J and a TEN3 tip. In fact, the tip on mine is marked TEN3. I've been happy with mine, but I don't have much to compare it to.

[Alistair]

I had a hard time finding the Victor UN-J mixer too. I ended up going with the Gentec mixer and tip from Torchtools. They have combos that have the mixer with the tip already attached. I think mine is the Gentec 17-3, which is the equivalent to the UN-J and a TEN3 tip. In fact, the tip on mine is marked TEN3. I've been happy with mine, but I don't have much to compare it to.

Cool, thanks. I was hoping to get Victor parts but I'll consider the Gentec stuff too if that's what's easier to find.

Alistair.

[Will Neide]

I had a hard time finding the Victor UN-J mixer too. I ended up going with the Gentec mixer and tip from Torchtools. They have combos that have the mixer with the tip already attached. I think mine is the Gentec 17-3, which is the equivalent to the UN-J and a TEN3 tip. In fact, the tip on mine is marked TEN3. I've been happy with mine, but I don't have much to compare it to.

Yep, I went with the Gentec mixer and tips from Torchtools. I would have prefered Victor, but I caved at the ease of purchasing from Torchtools. Overall seems to be quality stuff though. My LWS says they can order anything Victor, so maybe next time I'll just order the tips from them.

[Doug Fattic]

The one cautionary comment I'd make about the Gentec TEN tips from Torchtools is their difference from the Victor TEN tips (that screw onto the UN-J Mixer/elbow). The step down from the internal threads to the smaller orifice is a bit pointed like a drill point instead of being a square shoulder like the Victors. The problem is that I sometimes will get the flame leaking back towards the elbow (in other words coming out the back instead of the front like it is supposed to) which I find disconcerting. The square shouldered Victor TEN tips don't do this.

Torchtools sells a Gentec all-in-one screw-on tip/elbow/mixer unit. I haven't bought one so I don't know if the TEN tip unscrews or not. Do any of you know?

One of the things I noticed when shopping around for a Victor UN-J mixer and TEN tips is that sometimes the selling company takes your order but does not say whether it is in stock or not. Usually they aren't and then the company orders from Victor after you have placed your order with them (or wait longer until they have a big enough order to order from Victor). This can lead to long unexpected delays. Increasing the problem is that there often isn't a real person to talk to when ordering from some companies so you don't know if they have it in stock or not. Sometimes they email you back saying how long a delay is expected. The dilemma is that the places that have the cheapest prices can do so because they aren't stocking any inventory.

[dsaul]

Doug,

If you are referring to their G17 series, they consist of the 881W mixer/elbow and an 883TEN tip that unscrews from the elbow/mixer unit. It looks like they just have them pre-assembled for convenience. I haven't experienced the flame coming out the back of mine, but it may be that the Gentec tip and mixer work better together than using the Gentec tips on a Victor mixer.

[Pritchett]

I have an order in with Weldingsupply.com. I was excited to find a place that had EVERYTHING I needed, and they are located just a few miles from my home.

I ordered all the Doug Fattic approved Victor goodies, a smith Kevlar hose and flashback arrestors.

Soon after placing the order, I received an email stating that everything I ordered was not regularly stocked... Estimated wait is 10 days. I'm bummed, but hopeful that it all comes together soon.

I have a Devilbiss 525DS/Propane set up. I have been able to light an old harris torch with a welding tip, but not keep a good flame. I'm looking forward to having a working setup to begin practicing with.

[Doug Fattic]

The problem that I incurred with the flame coming out the back of the Gentec 883-TEN screw-on tip was caused – I think – by its different inside shape. The inside shoulder that transitions its size from threads that attach to the elbow to the tunnel of the orifice is tapered (like the shape of the end of a drill bit) instead of square. I believe this fault prevents the tip from sealing against the end of the elbow of the mixer. Propane is then able to leak around that connection and come out the back as a flame. I presume that the end of the mixer/elbow fits up tighter against a square shoulder (like the Victor) rather than a tapered shoulder (like the Gentec). I'm betting that the Gentec all-in-one-units (even though they can come apart) work better than buying the elbow/mixer and tips separately. I would not recommend buying the 881W mixer/elbow and several different sizes of 883TEN tips as separate items because of the problem I've had.

[Will Neide]

The problem that I incurred with the flame coming out the back of the Gentec 883-TEN screw-on tip was caused – I think – by its different inside shape. The inside shoulder that transitions its size from threads that attach to the elbow to the tunnel of the orifice is tapered (like the shape of the end of a drill bit) instead of square. I believe this fault prevents the tip from sealing against the end of the elbow of the mixer. Propane is then able to leak around that connection and come out the back as a flame. I presume that the end of the mixer/elbow fits up tighter against a square shoulder (like the Victor) rather than a tapered shoulder (like the Gentec). I'm betting that the Gentec all-in-one-units (even though they can come apart) work better than buying the elbow/mixer and tips separately. I would not recommend buying the 881W mixer/elbow and several different sizes of 883TEN tips as separate items because of the problem I've had.

I'm currently using the 881w with a TEN-3 tip. I ordered the combo 881w+TEN-2 (although they shipped me a TEN1), and I ordered an additional TEN-3 which I installed myself. I'll keep an eye on the back of the tip, but it really is a snug fit. I can't imagine any flame coming out the back.

[Jim Gourgoutis]

Great stuff as usual, Doug!

Question(s): Would you be able to take photos of the flames, perhaps one that was just lit and the other of what it would ideally look like with O2?

Hi All, first post here, but a longtime past participant in iBOB and lurker on the Framebuilders' List. I've talked about O2 concentrators at some depth with Alistair and Alex. I've read a lot in various glass and lampworkers forums about using O2 concentrators and propane to fuel a torch. This particular thread, in a general metalworking forum, has photos of an oxy/propane torch flame, as well as a good list of parts to use for a J-28-style torch: http://www.chaski.org/homemachinist/...p?f=12&t=87931

I've got an O2 concentrator on order from Unlimited Oxygen -- their M5/M10 unit. Following a tip I got from Legacy Frameworks in this Framebuilders' List thread, I bought a $40 Hoke Jeweler's torch from Ebay -- my main interest at this point is rack-building, and I think this torch will be great for that. I'll upgrade to a J-28-style torch at some later point if I need to. I'm planning to get this National regulator and hoses, check valves, and flashback arrestors there as well.

Cheers!
-Jim G

[veryredbike]

Is there any need for a reg with two gauges? The vapor pressure in the tank shouldn't swing much until it's just shy of empty.

[Doug Fattic]

Is there any need for a reg with two gauges? The vapor pressure in the tank shouldn't swing much until it's just shy of empty.

No there isn't. Unlike acetylene, tank pressure does not indicate how much is left. In our frame shop in Ukraine we use some kind of cheap propane regulator that only has one gauge. There is a gauge for BBQ units I bought at Lowe's that I stuck in between the tank and the regulator that tells me how much propane i have left.

[Alistair]

Hi All, first post here, but a longtime past participant in iBOB and lurker on the Framebuilders' List.

Hey there Jim, welcome. Good to see you here. Thanks for those links too, good info there.

Alistair.

[Jim Gourgoutis]

Is there any need for a reg with two gauges? The vapor pressure in the tank shouldn't swing much until it's just shy of empty.

Some of the lamp worker folks use a simple pancake-style regulator without any gauges.

[Jim Gourgoutis]

No there isn't. Unlike acetylene, tank pressure does not indicate how much is left. In our frame shop in Ukraine we use some kind of cheap propane regulator that only has one gauge. There is a gauge for BBQ units I bought at Lowe's that I stuck in between the tank and the regulator that tells me how much propane i have left.

Doug, is this the gauge you got?

http://www.lowes.com/pd_231786-66482-80064L_4294703218__?productId=3352972&Ns=p_product _qty_sales_dollar%7C1&pl=1&currentURL=%3FNs%3Dp_pr oduct_qty_sales_dollar%7C1&facetInfo=