acetylene vs propane

[Andrew R Stewart]

Jim- I began to reply to your earlier post but lost it to the electronic winds.

Which is a good slide into my answer to your outside brazing question. Any wind/breeze control is good. A big fence close to where you're working is better then nothing. But the wind does shift and flow around things so having more then one side protected is best. Watching your flame curl away from the joint as well as the frame cool off in the breeze is not good. I also started to plug the tubes (loosely to allow for gas expansion) to reduce the chimney effect that happens when brazing. With the cold air the cooling effect is greater. An aspect not mentioned much is the lighting. Depending of the sunshine and your set up the brightness factor can be challenging. My event tent (white nylon) with the three sides produced a lighting that made discerning the metal's color changes hard. I had to get back to the basic of watching the flux fot temp guide lines. I never found any gas line pressure issues or regulator problems down to the mid 20s i worked in. Andy.

[veryredbike]

Hmm... Ok... so I should work on a way to do it inside, since I'm new and don't need extra challenge (thanks!). That's harder. If I can use the 1lb propane cans for camp stoves (not have to store real quantities, as I don't have any access to outdoor areas there), I have a space I can use. It's pretty big, 20 foot ceilings and some good floorspace, but the ventilation might not be ideal.

There's a small area at one end of the ceiling that seems to be open to the outside. There's a big fan unit, but it just circulates air, doesn't get it out of the building. There's a front door that I could open a bit, but it's not ideal since there's foot-traffic outside and I think that people would try to come in, or might freak out about brazing smell.

In such a large space, is a fan at the door enough? Can I leave the door closed if I use a fan with a dryer vent hose running up to that open area at the top, or do I have to rout it all the way outside (seal the hose around the whole vent area)? This is assuming that I use a respirator while the torch is actually going.

Thanks,
Jim

[Greensabbath]

Thanks again for starting this thread and filling it up with very useful information. Santa was very kind this Christmas and I got most of what I need for my Oxy/Propane rig. The one thing that I am still trying to decide on is the Oxygen. I was originally going to purchase either an 80 cf or 120 cf tank and get it refilled down the road but that seems like an expensive option given that a decent concentrator like this one DEVILBISS 525DS Oxygen Concentrator For Sale - DOTmed Listing #1270819: will only cost around 200 bucks and won't require refilling. Is buying the concentrator the best way to go? ie will it provide good results or does the oxygen cylinder provide a better flame? I noticed the purity on the concentrator says its about 90% but I do not know if that means anything to me. Thanks again.

[Doug Fattic]

I started this thread because for some using propane with a concentrator is the cheapest and most convenient option in some locations. I've always used oxyacetylene as my primary gases in my shop in the US and for 10 years have used oxypropane in Ukraine with bottled oxygen. For the last month or so I've compared the Oxygen concentrator with bottled oxygen side by side in my shop. In this test I was usually hooked up to propane but I also tried it with acetylene. I can't tell any difference between the two (meaning the bottle or the concentrator) when using either propane or acetylene. They both work just fine with oxygen coming from either source.

I did take me a little bit of time to learn how to use the concentrator because it doesn't come with any instructions on how to use it for brazing. There are 2 issues. The first is that it takes some time to fill up the internal reservoir so it has a steady flow. I was trying to turn it on and immediately light the torch. That didn't work and I had to learn to wait a couple of minutes. I adjust by just turning it on before positioning the work or applying flux. No big deal. The second is that I had to figure out how to regulate the liters per minute oxygen flow rate on the concentrator. It has a turn knob that increases or decreases the flow rate with a ball going up or down a tube to tell you what it is from 0 to 5 lpm. It can actually deliver more but the regulator tube doesn't show how much past 5. Now that little indicator ball is effected not only by how far the the knob is adjusted on the concentrator but also by how much the torch knob is opened. With the Victor 2-TEN or Smith LT104 tip I find I need to set the flow rate somewhere between 2 and 3 after the oxygen knob on the torch handle is approximately adjusted.

I will say that if I turn up the oxygen knob on the torch handle when using the concentrator so it becomes an oxidizing flame (more oxygen than propane causing it to turn more blue) it seems to blow out the flame while with bottled oxygen it just becomes a bluer flame. It is easy to over adjust the knob because it is so small of a turn (maybe a 1/16th of a revolution). This might become an issue for clumsy hands. It won't blow out if the torch is set correctly unless the concentrator knob is turned up too far. So there is a fussiness learning curve with propane (especially with a concentrator) to get the flame adjustment just right so it doesn't become detached nor blows itself out. Acetylene always seems much easier by comparison. When I go to Ukraine it always takes me 10 tries at least before I get just the right amount of flame with only propane so it is still attached to the tip, then I add the oxygen and then more propane and then more oxygen without blowing out the flame. In other words propane takes 2 adjustment steps while acetylene only requires one.

My local welding supply story sells the 80 cubic feet oxygen tank for $270. It costs $15.50 for each refill. The the 125 cubit foot tank is $315 and $18 for a refill. A oxygen tank regulator is going to be around $80 to $100 (although I use a more expensive Victor VTS 450 because I want an absolutely seedy flow rate). So it's obvious that if one can find a decent concentrator for $200 and never need a refill that is the better deal. I does have some background noise if that matters.

Late at night in my last framebuilding class my last bottled oxygen tank ran out (I have 2). No problem the students just switched to the concentrator and kept brazing. I used to always worry that I'd run out on the week ends or after 5 and have to stop work. I didn't like to take a bottle with too much left to be exchanged on Friday or any late afternoon. It is a time hassle to change before it runs out. Of course with a concentrator I don't have to worry about that.

[shirk]

Found a local oxygen concentrator for a pretty good price. Glad to find one local unit and not have to deal with shipping or border issues bringing it into Canada from any of the cheap US bases sources.

I recommend calling any local company that works with these and see what they have. The unit I am getting has cosmetic damages to the case. Originally when I spoke to the sales guy he didn't have anything in the price range I was willing to spend. He called back after checking and they decided it would be better to sell off a unit with a damaged case vs investing the money into making it look perfect and go back into medial service in someones home.

Pretty excited to finally be putting together all the pieces to start my first frame.

[Tremdo]

Hi,

Sorry if i have weird questions (and its my first post... + i am a really newby at brazing and frenchy quebecer haha!)

But there it is:

Wondering if a Victor performer (model) rig will work with Berzomatic Oxygen and propane or Map little gaz tank? Maybe with some minor adjustement and additional connector..? Lets say with at least the torch and let me know about the regulator?

I know (i think i read that somewhere) that oxygen go out faster than acetylen/propane, so don't know if its worth it (Bernzomatic are really small...).

I just want to start with little braze on and drop out modification. Worry about carying big acetylen rig in my small work space + trouble..

Thanks and sorry again! ishh!

[veryredbike]

Alright, this is what I'm thinking of getting myself. There's a place locally that sells a couple oxygen concetrators per month on craigslist for $150ish. I'm going to keep my eyes on it... no blinking.

3/16 - T Grade Oxy-Fuel A-B Twin Hose [TH316-T-AB] - $33.96 : Arc-Zone.com, The Welding Accessory Experts
Hose $55

Gentec FlashBack Arrestors FA5TPR Pair, Oxy - Fuel, Torch-End Flashback Arrestors
FBA $44

Amazon.com: Ameriflame R361-510 Heavy Duty Single Stage LP Gas Regulator with CGA510 Inlet: Home Improvement
Regulator $53.99

Ameriflame MD71TH 6-Inch Light Duty Welding Handle for General Purpose Heating, Brazing, Welding and Other Flame Processes - Amazon.com
Torch $39.00

Resever Cylinder Adapter
Adapter for camp cylinders $22

GENTEC 171W Welding Brazing Tips sizes 000-6, equivalent to VICTOR W-J
tip 2: $26

NU-CALGON Leak Detector, High Viscosity, -20 To 220F - AC Refrigeration Accessories - 2RZW4|4183-24 - Grainger Industrial Supply
leak detector $15

[Will Neide]

Doug (or anyone)......where do you recommend the flashback arrestors and check valves to be placed. A google search yielded mixed opinions. Some folks recommended just arrestors with no check valves, and then their seems to be the issue of placing the arrestors at the torch or regulator.

Would arrestors at the regulator and check valves at the torch be optimal?

[cardinal-creative]

Doug (or anyone)......where do you recommend the flashback arrestors and check valves to be placed. A google search yielded mixed opinions. Some folks recommended just arrestors with no check valves, and then their seems to be the issue of placing the arrestors at the torch or regulator.

Would arrestors at the regulator and check valves at the torch be optimal?

I use Harris arrestors (Flashguard) that have check valves built in. Not sure of other brands or models having this feature, but seem to remember Victor arrestors advertising the same thing. Additionally, some Victor torch handles have check valves built in.

I prefer mine at regulator, not at the torch. Reason being is that I'm more comfortable with the protection at the bottle rather than an issue arise in the hose where a torch mounted arrestor can't do it's job.

[suhacycles]

I use Harris arrestors (Flashguard) that have check valves built in. Not sure of other brands or models having this feature, but seem to remember Victor arrestors advertising the same thing. Additionally, some Victor torch handles have check valves built in.

I prefer mine at regulator, not at the torch. Reason being is that I'm more comfortable with the protection at the bottle rather than an issue arise in the hose where a torch mounted arrestor can't do it's job.

Hey, nice little shop ya got there. What TIG welder do you use if I may ask?

[cardinal-creative]

Hey, nice little shop ya got there. What TIG welder do you use if I may ask?

It's an old Airco Heliwelder. Rescued from a dusty barn and given a new life. The cooler had to be rebuilt thanks to a leak for who knows how long, but the rest just needed cleaning since it is a trusty transformer machine.

These machines are usually overlooked since it's not a Miller or Lincoln, but they are just as good imo.

[Doug Fattic]

Doug (or anyone)......where do you recommend the flashback arrestors and check valves to be placed. A google search yielded mixed opinions. Some folks recommended just arrestors with no check valves, and then their seems to be the issue of placing the arrestors at the torch or regulator.

Would arrestors at the regulator and check valves at the torch be optimal?

I'm not a safety expert and when I've asked various people I thought were authorities I've gotten mixed messages. What I do is put an A size check valve on the end of my airline type of torch handle. I would not ever want a bigger torch handle. My B size flame arrestor is the connector between the Smith Kevlar or super light TM hose (that are attached to the torch) and the 3/16" rubber hose that goes to the regulators on the tanks. This arrangement seems to make the most sense to me. I hang my hoses from the ceiling so they don't drag on the floor.

[Will Neide]

Thanks guys! Looks like I'll be putting them at the regulator (and concentrator).

[Doug Fattic]

My initial reason to start this subject thread about using propane instead of acetylene for brazing bicycle frames was for its cheaper start up costs and greater convenience of supply. I know that some of my students (which come from everywhere in the US and many from foreign countries) don't live close to a welding supply store. However I'm also discovering another advantage of propane and that is how long a tank of propane (the kind sold locally at supermarkets, gas stations and hardware stores) will last. Apparently a long time. Roughly I go through a 80 size tank of acetylene in about a class and a half. It costs me $36 for a refill. I have three students making three frames (with the help of my assistant Herbie Helm). They will also do quite a few practice joints and Herbie and I will give a number of demonstrations. A student can easily take 3 or more times as long to braze a joint as Herbie or I. I've never timed myself but I'd guess I take 3 to 5 minutes to do a typical braze. A student will be take about 15 minutes and often longer than that if they are still trying to catch on.

I'm more than half way through a 2nd class since I set up the propane tank and I've only used a third of a tank. It isn't a perfect comparison because only 2 students were using the propane each time while the other was on oxyacetylene but it does seem my small propane tank is lasting a lot longer than the large acetylene tank. The propane tank refill is $17. The propane unit is hooked up to an oxygen concentrator so I won't have oxygen costs either. So it appears the small propane tank I buy is half the cost of my large acetylene tank and is lasting much longer. One other factor in this cost equation is that a propane flame is cooler than an acetylene one. I compensate by using a larger tip to get a bigger flame. So it can take me a bit longer to get some joints like forged dropouts up to brazing temperature.

Has anyone else done a comparison of time a propane tank will last vs acetylene? This was a use cost bonus I wasn't expecting. I've used propane a lot making frames in Ukraine and the tank seemed to last a very long time (looked the same as the US versions) but I didn't have anything to directly compare it too.

[EFHeath]

Great thread; thank you for starting it, Doug.

Can anyone expand on what the deficiencies of the Meco Midget torch might be? According to the Tin Man Tech website, they offer longer tips in the larger sizes to avoid excessive heat, rosebud tips, and dedicated propane tips. Also, the Mecos are supposed to be fine for welding up a 4130 tube aircraft fuselage, and welding long joints like body panels. Before I commit to a "system" I would like to better understand why they seem to be dismissed by the framebuilding community. Any comments?

[EFHeath]

Apologize for OT digression:

Doug, I was unsuccessfully looking around online for a schedule of your classes in summer 2013; can you point me in the right direction?

Thank you,

Ethan

[Doug Fattic]

Great thread; thank you for starting it, Doug.

Can anyone expand on what the deficiencies of the Meco Midget torch might be? According to the Tin Man Tech website, they offer longer tips in the larger sizes to avoid excessive heat, rosebud tips, and dedicated propane tips. Also, the Mecos are supposed to be fine for welding up a 4130 tube aircraft fuselage, and welding long joints like body panels. Before I commit to a "system" I would like to better understand why they seem to be dismissed by the framebuilding community. Any comments?

My impression of the Meco Midget torch handle is that it falls into the really like it or don't category. Its more box like shape doesn't appeal to me at all but I've had a couple of students that have brought them to class and loved them. I simply like holding a round handle better than a square one. Your opinion may be different. Meco is not nearly as commonly available from suppliers (except of course from TM) so the percentage of chance someone can try it out and promote it is reduced. As near as I can tell it is a fine torch but with a quirky personality. The knobs being positioned with their stem being parallel to the body is another difference from other handles. It's like using something else besides Shimano, Campagnolo or Sram for bicycle components.

[Doug Fattic]

Apologize for OT digression:
Doug, I was unsuccessfully looking around online for a schedule of your classes in summer 2013; can you point me in the right direction?
Thank you, Ethan

Email me directly and I can send you lots of information in return. In your email also include your mailing address and I can mail you a brochure. I don't put much information about my classes online because they always fill early and I don't need to become a secretary to take care of additional inquiries. I benefit from having several degrees in the field of teaching education (including Michigan state certification grades 7 to 12) and was one of the original Americans to apprentice in Europe.

I've delayed scheduling my 2013 summer classes. I was waiting to hear from Ukraine that the bicycle parts we had shipped over to equip the frames we made for pastors had arrived. Some import laws had changed and they got stuck in customs. I should know soon. Most likely it will be in August.

My schedule of classes follow a similar pattern every year. One in Jan/Feb, others in March, May, summer (sometimes 2), October and first of December. Mostly I teach 3 week classes because there is a lot to learn but a couple of times a year I'll do shorter ones. Occasionally I'll squeeze in a frame painting class. I'm thinking about having a summer class in Ukraine this year. The frame shop is on a nice college campus where we can stay in a dorm and eat in a cafeteria. It's about 25 km west of Kiev. We've got a stable of bicycles for evening rides. And no, you don't need to know Russian to stay there. Its a very interesting country.

[afwalker]

Follow up on post #21:
I got the Ameriflame MD71TH torch and acetylene tips to replace my Meco midget. I like both and the 71 handle feels nice, good balance. I was used to the boxy Midget and they both work fine. I wanted more heat to do fork crowns and the 71 will do it. I guess I could have gotten larger tips for the Midget and been just fine. I guess the grass was only slightly greener after I got there:) Anywho, I heard there's a Midget for sale on classified's
cheers
andy walker

[veryredbike]

20130209_183056.jpg

Here's my setup!

Ran into one main issue: when I use a flashback arrestor on oxy, the flow drops from 5+ lpm to 1.5-2.5 lpm... I guess this older unit produces less pressure than the devilbliss. I can't get enough oxygen to really keep it going. I visited some forums (mostly glasswork for concentrator info) and found that most folks were saying that the arrestors weren't necessary with the concentrator, because it won't explode like a high pressure tank and the hose doesn't get pressurized enough to make explosion there likely. It seemed like this wasn't an uncommon issue.

I'll still be using an arrestor on the propane line, and probably a check valve on the oxy line if I can find one that reduces flow less than a flashback arrestor does.

Secondary issue: when I use enough propane to get a nice hot flame, it tends to detach from the tip. I'm using a tip rated for fuel, but it doesn't have a recess. I think I'll just go back and buy a w-j elbow and tips unless anyone feels comfy saying "oh, yeah, just jam a reamer in the end and open it up a bit"... shouldn't have tried to save money on that end in the first place.

It took a while to figure out a way to hold the propane securely without putting all of the weight of the (kinda heavy) regulator and adapter on the little disposable tank's threads. I'm using a display stand for a bicycle that'd normally grab it right around the non-drive locknut of the rear wheel. It's a lot heavier than it looks, and the center of gravity is close to the middle, so it's pretty stable and sturdy.

But, all in all, a good day. No leaks on the first pass with leak check and I can already get a piece of pretty thick steel tube glowing red. Can't wait to get a better tip and get a better flame out of it. Next step... spend some time practicing so that I can figure out what a neutral flame looks like with propane, definitely some differences from acet.