acetylene vs propane

[Doug Fattic]

I thought some information about the differences between using oxyacetylene or oxygen/propane might be interesting for those wanting to get their own equipment to make frames. I've used both. I learned how to hearth braze (a giant natural gas flame heating up a whole joint surrounding by firebricks) when I apprenticed in England as well as braze with brass using an oxyacetylene torch. We set up our framebuilding shop in Ukraine (where we make bicycles for pastors) with an oxygen/propane unit. I use oxyacetylene in my shop in Niles, MI and have recently set up to braze with propane as well. It is possible that some might like to use propane because it can be much easier to buy and transport and possibly be cheaper. Sometimes city ordinances prevent its use in residential areas (particularly in big cities) and sometimes welding supply stores won't sell bottled gases to non businesses or let you leave with one of their/your bottles unless it is carried certain ways. And insurance policies may limit where acetylene tanks can be located. Propane is less regulated because of its common home use in grills, etc. Welding stores can be ignored entirely if an oxygen concentrator is used instead of bottled oxygen. Those are the machines that keep grandma alive when her lungs aren't working well any more. Many of my framebuilding class students find using propane a better option. Here are some of my observations between the 2 types of fuel.

A propane torch is slightly more fussy to light than acetylene but has a cleaner flame. It doesn't rain soot if it isn't turned up rapidly enough. A propane flame wants to detach itself off of the torch tip. Once oxygen is added it can be turned up more. It will blow itself out easily if the adjusting knobs are turned slightly too much. Propane doesn't have distinctive visible inner cones like acetylene to assist in adjusting to a neutral flame. Its also noisier. It is necessary to go up a tip size or two to get the same heat volume. For example I commonly use a Smith AW205 tip on my AW1A torch handle. In Ukraine I use the AW207 with propane.

A propane flame isn't quite as hot and the bigger tip required to put out the same amount of heat isn't quite as sharp. This isn't usually a difficulty when silver brazing lugs. And could actually be an advantage for beginners because it is slower to heat up giving them more time to analyze and adjust. However I feel it makes fillet brazing a little more challenging. That said I fillet braze joints in Ukraine with propane without any difficulty. It is easy for me to adjust to using either one.

While most oxyacetylene equipment will work with propane, some adjustments will make it work better. For starters, Victor propane #-TEN torch tips have a slight recess at the end of the tip hole to help keep the flame attached. They screw onto the end of a UN-J mixer/elbow that attaches to a J-28 torch handle. Smith's NE series of propane tips designed to screw onto the end of their propane only AT61 mixer/elbow (that go to their AW1A handle) are too big for general framebuilding use. They don't have a recess in their tip. The Victor UN-J unit can also be used with acetylene with their TE series of tips. The T series of rubber hoses are recommend for propane. Standard welding hoses won't last as long.

How to use an oxygen concentrator instead of bottled oxygen is a separate subject.

[Straz]

Great post. I am very interested in hearing about using an oxygen concentrator.

[devlin]

I am looking at getting a propane torch rather than acet. for the reasons you mentioned. ie. transport, storage and availability. Thanks for highlighting the difference in use though, some great info there.

I have one question. Would the town gas supply to our house that we use for the stove be suitable for use. Is the supply pressure the thing to look at here?Obviously you lose the portable nature of having bottles but I would probably only need that feature once every couple of years. So no real loss.

With an oxygen concentrator (depending on cost and practical use) I could do away with bottles all together.

[devlin]

Just went and did the google thing. Haven't answered the town gas supply thing but found plenty on the Oxygen concentrators.

[Doug Fattic]

Oxygen generators come in 5, 10, 15 liter per minute outputs. They have replaced small oxygen tanks used to assist breathing for those with health problems. They take the other stuff out of the air and deliver almost pure oxygen. There are federal regulations governing the sale or rental of this kind of medical equipment – which is often paid for by insurance. You have to have a doctor's prescription to get one from a medical supply place where they are really expensive. However there are places that refurbish and sell them for non-medical use – typically lampworking (melting and shaping glass). Occasionally a spouse will sell them after the partner is gone in the classifieds or on craigslist. In my local South Bend Tribune there was one for $200 a few weeks ago although I didn't call soon enough. I bought a reconditioned Devilbis 5 liter one outright from a company that refurbishes them in PA for $350 + $30 shipping. It has a 36 month warranty. They are designed to run something like 10,000 hours before needing to be sent back to the factory for reconditioning again. The online Jewelry supply company RioGrande sells them new for $425. Because they don't require a regulator or be refilled, getting one might be a financially attractive and/or more convenient option.

I put one of my Victor acetylene regulators with 510 fittings directly on my propane tank. Regulators for the smallest tanks have a different fitting. The barbed oxygen outlet on my concentrator (that accepts clear plastic tubes) can be unscrewed and a welding hose with a "B" fitting can be screwed directly onto the outlet. You don't need an oxygen regulator. It is necessary to let the concentrator run a bit (2 or 3 minutes) before it has a steady flow rate. Otherwise its initial bursts of oxygen will blow out the flame. If you don't have the oxygen knob on the torch open when it is running, it will beep a warning. There is a dial on the unit that regulates the flow from 0 to 5 lpm (liters per minute). This needs to be adjusted to the tip size. I typically use Victor 2-TEN to 4-TEN tips. Conveniently a size 2 tip seems to require about a 2 lpm flow rate and a 4 tip 4 lpm (give or take). If the flow rate isn't right, it will blow out the flame. There certainly is a much longer learning curve to getting the settings right.

They create a background noise similar to an inverter welder. They aren't noisy but aren't quiet either. And of course a propane flame is noisier than an acetylene one too. This combination shouldn't be strong enough to be a deal breaker for anyone but one should be aware and prepared for this additional noise in case they are used to enjoying the quiet of oxyacetylene.

[echelon_john]

Look at MAPP/Chemtane as well.

[Greensabbath]

Thanks for posting this. I am hoping to get a oxy-propane brazing rig for Christmas and I am still trying to figure out what to get. If the Smith NE tips are too big then which tips would you recommend when going the Smith route? Or should I just go the victor route with the TEN tips?

[Alistair]

Look at MAPP/Chemtane as well.

I'm pretty sure MAPP is dicontinued, but Chemtane is available. The big gas supply houses (Praxair, AirGas etc.) often have their own house brand of Propylene with names like AgFuel, FG-2, FlameAll etc.

Sometimes they're just straight Propylene, but sometimes they're souped up with some additives. I use Acetylene, but I think the alternatives are interesting to look at.

Alistair.

[Doug Fattic]

Thanks for posting this. I am hoping to get a oxy-propane brazing rig for Christmas and I am still trying to figure out what to get. If the Smith NE tips are too big then which tips would you recommend when going the Smith route? Or should I just go the victor route with the TEN tips?

Smith doesn't recess their tips like Victor does. I use the standard Smith AW207 tip on a AW1A torch handle in Ukraine. It works fine but not quite as well as the Victor TEN tips on a UN-J mixer. The Victor controlled flame doesn't detach as easily and seems to have a sharper point. Smith used to make mixer/tips specific for propane in their AW line. They were the AW40# series (the # representing the number of a specific sized orifice – for example AW407. I would presume that to be the same size orifice as the AW207). I don't think they make them any more just like they quit making the AW204 tip assuming either the AW203 or AW205 was close enough.

If I didn't have a torch handle already and was on somewhat of a budget, I'd get the Uniweld 71. It is similar to the Victor J-28 and accepts the same mixers. It has a slightly larger diameter and longer handle with bigger aluminum knobs. It is slightly lighter. On my Park scale the Uniweld handle weighed 85 grams by itself and the Victor weighed 124. I can actually tell the difference in my hand although it really doesn't matter. It will cost under $100 if you look around online and the J-28 a bit more than $150.

It is possible to buy clones of the Victor UN-J mixer and TEN tips for less money too. However they don't seem to be quite as well made. For example the Gentec 883-3 tip which is equal to the Victor 3-TEN tip does not have a square inside shoulder where the thread-on part is reduced in size to the orifice. It is domed a bit like the shape of the end of a drill bit. It doesn't seem like much of a difference but on a couple of my Gentec tips, flame would sometimes come out the back of the tip. I found that unsettling.

Uniweld says its 17 line of tips for the 71 handle work with all fuels. I've tried the size 2 and it did work with both propane and acetylene but of course all acetylene tips seem to work with propane. You just have to fuss with the settings more carefully or the flame will blow out. In your letter to Santa if you've been nice, you might want to ask him for some light hoses too. Either the Smith Kevlar ones or the slightly heavier and tougher ones made by TM technologies.

[devlin]

Your blood is worth bottling Doug. So many answers to the questions I didn't know I had. Thank you sir.

[Doug Fattic]

What type of torch handle to buy: “Airline” torch handles are the best type to get for brazing bicycle frames. They are characterized by their smaller size, have their adjusting knobs at the top of the handle and use smaller “A” size hose fittings. A light torch makes the subtle and slight brazing motions used in building frames more precise and comfortable. Usually they have to be bought as a separate item. Most torch handles found in pre-packaged kits (including regulators, etc.) are designed for use with a cutting head attachment that need bigger bodies (that are unnecessarily heavy for our purposes) and have the knobs located at the bottom of the handle near their larger “’B” hose fittings. When the knobs are located at the top, it is much easier to adjust the flame with one hand. Students that bring a larger torch handle to class don’t want to use them after trying out an airline torch handle. Smaller torches designed for jewelry applications get too hot to work properly when brazing bicycle joints.

Comparing torch handles: The Smith AW1A and Victor J28 “Airline” torch handles are commonly available and a popular choice for brazing bicycle frames. The AW1A is chrome plated and has a slightly bigger diameter handle with a shorter body between the knobs and the hoses than the J-28. The knobs are a little less sensitive to adjustment because they require a bit more of a turn than the Victor. Smith brazing tips have a knurled section at their base because they are designed to be screwed on by hand. The Victor torch is brass and comes with small check valves (that stops the flow of gas going back) that attaches to the bottom of the handle. It has more length on its slightly more slender handle than the AW1A between the hose connections and the adjusting knobs. There are several torches that are essentially exact copies of the Victor J-28 torch but sell for a cheaper price like the Gentec or Metalweld 140T. The Uniweld 71 torch is similar to the J-28. It is slightly lighter and has a larger diameter handle with bigger aluminum control knobs. I like using it. All these Victor clones take the same mixers and/or tips as the J-28. The Smith AW1A costs just over $100 online. The Harris 15-3 is an airline torch with a slightly larger diameter handle than other airline handles. It is also more expensive. The Concoa style 450 has a slightly oval handle as does the Purox W-200 sold by Esab. I haven’t tried the Harris, Concoa or Esab airline models to have any opinion about them. I used a bigger Harris 16 torch handle in Ukraine until I took over an AW1A. It worked fine except for my preference for a smaller torch.

[Doug Fattic]

The first picture shows the Smith AW1A on the bottom and the Uniweld 71 on the top. The Victor J-28 is in the center. Their normal acetylene mixer/elbow/tips are attached. In the 2nd picture, the Smith AT61 + screw-on tip is on the left, the Victor UN-J with a 3-TEN screw-on tip is in the center. On the right is the Gentec 881W with 883-3 screw-on tip. The Gentec unit is a near copy of Victor's. The Victor and Smith torches have Smith Kevlar hoses attached and the Uniweld the light hoses from TM Technologies.

photo[3].JPGphoto[4].JPG

[Mike Mcdermid]

this has to be one of the most interesting reads i have had in ages

I heard read somewhere acetylene is running out (maybe not in our lifetime like)

actually forget the above complete im talking bollocks its "helium" turns out any oil refinery with a catalytic cracker can make acetylene or something

[afwalker]

Candidate for frame forum wiki best threads?
The envelope please
cheers
andy walker

[Honus]

I have one question. Would the town gas supply to our house that we use for the stove be suitable for use. Is the supply pressure the thing to look at here?Obviously you lose the portable nature of having bottles but I would probably only need that feature once every couple of years. So no real loss.

With an oxygen concentrator (depending on cost and practical use) I could do away with bottles all together.

At my work (jewelry making) we use oxygen tanks along with natural gas that is piped into the building (at around 5psi) but it's not as hot as propane. We have a propane/oxy setup for casting metals because of this. Natural gas is cleaner though. A lot of mall jewelry stores use oxygen concentrators and natural gas because they aren't allowed to have indoor tanks. Many city ordinances also do not allow propane tanks to be stored indoors- be sure to check with a local fire department to make sure it will pass inspection. When looking for an oxygen concentrator be sure to check out jewelry stores that are going out of business. Ditto for tanks.

[devlin]

Tanks (pun inteneded) Honus

[dsaul]

If anyone was looking for the Uniweld 71 torch, Amazon has it for $35 with free shipping.

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

[shiggy]

Doug, I am playing setup for dummies here.

I finally decided I need to have a setup so I can again fillet braze my own frames and such. I have nothing at this point (other than cold metal working tools). Could you please make a simple, complete list of what is needed, at the lowest cost? Tough to search when there are many options and I do not really understand the requirements.

Will be working in a small garage where I can not leave it set up.

Thanks, shiggy

[Doug Fattic]

Shiggy,

Sure, it can be confusing to try and figure out not only what all is needed and which specific pieces of equipment go together but also where to find them on various websites. They often make it difficult to locate a specific item and don't indicate what tips match which handles. I'll describe what's needed for propane because it is probably your cheapest and most convenient option. It is also possible to use those small portable oxyacetylene units if you don't mind running to your local welding supply store for refills. I'll list the Victor clones because they are cheaper and you indicated price was important. Personally as a pro I prefer getting the authentic Victor or Smith stuff for myself. My philosophy is that one should buy as good equipment as possible when it is frequently used and made in the USA if I can afford it.

I just went to the shop and did a practice fillet brazed joint using propane. I prefer oxyacetylene for fillet brazing but I can do it just fine with propane. Part of the difference is what I'm used to but logic says a more pointed and hotter acetylene flame is better for greater brass control. My students have preferred propane when silver brazing. In this experiment I used my Victor J-28 torch handle with a Gentec 881W elbow (which is a copy of the Victor UN-J) and the Gentec 883TEN-2 screw on tip (which is almost like the Victor 2-TEN except not as well made). I could lay down an almost perfect fillet brazed joint with that combination. I also tried another joint with my Uniweld 71 torch with a 17-2 elbow tip. I liked the TEN-2 tip better because the flame on the 17-2 tip would easily go out from gas blow back bouncing off of the fillet (if the angle was right). When I'm concentrating on shaping the fillet, I don't want to also be thinking about keeping the angle away from making that happen. That little recess on the end of the TEN tip really helps keep the flame going. The propane tank came from the Supermarket a couple of blocks away and the oxygen was supplied by an oxygen concentrator. I set the propane pressure on the regulator (a cheaper propane regulator works okay and better than a cheap regulator with acetylene) somewhere between 4 and 5 PSI. The concentrator doesn’t need a regulator and I set its LPM (liters per minute) output a bit more than 2. I have to let it run for a couple of minutes before its output stabilizes enough for use.

My equipment list starts with a propane tank (the kind used in home grills that you can buy almost anywhere full for around $50). You will want to put on a propane regulator of your choice that has a matching CGA510 tank fitting. Some propane regulators use a smaller 300 tank fitting. I would certainly want one with 2 gauges so I can tell when the tank is getting empty as well as what pressure it puts in the hose. Some have only 1 gauge for setting line pressure. The regulator will probably have a "B" hose fitting. If the distance from the tank to the torch is of some length (and for safety it should be) you will want to put on the smallest 3/16" type T rubber hoses (they stand up better to propane than U hoses) with B fittings on each end to extend its length. I hang these from the ceiling so they don't drag on the ground. On the other end of the hose I would put a flashback arrestor (to stop a runaway flame). I really, really prefer a light hose going to my torch handle and there are 2 options that I know of, the Smith Kevlar hose (with its B fitting end screwed onto the arrestor) or the TM technologies ultra lightweight hose. The TM hose is slightly tougher (one drop of hot flux can kill a Kevlar hose) but is also a bit heavier (I can tell the difference in my hand). The other end of the Kevlar hose will have an A fitting to screw onto the check values that are placed on the end of your torch handle. The least expensive torch handles are the Uniweld 71 or Gentec or Metalmaster 140T. They are like or similar to the Victor J-28 and cost about $70 to $100. The Victor is over $150. The Uniweld 17 tip is designated for all fuels including propane and fits on all Victor type handles. It doesn't have a recessed tip like the Victor propane specific TEN tips but it works and is your cheapest option. My favorite combination is the Victor UN-J mixer/elbow that has a threaded end to except interchangeable TEN tips of difference sizes (TEN is Victor's designation for its propane tips. TE tips are for acetylene). They have a recess on the end of the orifice that helps keep the flame attached to the tip (a problem with propane but not with acetylene). The size of Victor tips I use for propane are the #2, 3 and occasionally a #4. If you are on a tight budget, a #2 can do everything.

Most online welding stores (particularly the ones with the best prices) don't keep propane tips in stock. Strangely they often carry either the torch handle or the tips but not both. They might have some things in inventory but not all. They order them from the mother company after you have placed your order. It takes 2 or 3 weeks for them to finally arrive at your address. The torchtools.com company on Long Island, NY that carry the Gentec brand had everything in stock that I ordered. It can sometimes be difficult to find a specific item using a company's search feature on their website. For example I might type in "Victor 2-TEN tip" (or leave out the "Victor" or the "tip") and come up with nothing. However if I type in the Victor part number for their 2-TEN tip - 0311–0485 – it will show the part. Sometimes it is the other way around. Comparative price checking between different websites drives me crazy. Here is my list of equipment for brazing with propane:

1. Propane tank from a local store
2. Propane regulator with 2 gauges for both line and tank pressures with CGA 510 tank fittings
3. 5 LPM Oxygen concentrator (it does not need an oxygen regulator)
a) or an oxygen tank from a local welding supply store
b) They come in 20, 40, 60, 80, 125, 150 and 251 cubic feet sizes with prices from $75 to $350
i) which requires an oxygen regulator. It is preferable to get one with the least wide oxygen pressure settings (like 0 –40 psi instead of 0 – 100)
4. Type T 3/16" hoses (the smallest) with B fittings on each end (probably 12 foot length – 25 or 50 ft. is also an option)
5. "B" size flashback arrestors to connect the 2 hoses
6. Smith Kevlar 10' hose with A and B fittings ($70+) (Smith part # 14779-4-10) (this is optional since you can run a T hose to the torch)
a) or TM technologies light hose (item # AWS-0052) ($45)
7. "A" size check valves that stop the back flow of gas but not a flame (can be optional).
8. Uniweld 71 "airline" torch handle
a) or the Gentec or Metalmaster 140T or the Victor J-28
9. Gentec 881 elbow (the equivalent to the Victor UN-J) (Victor part # 0325-0101) (this unit also needs a separate screw-on TEN tip)
a) with Gentec 883TEN-2 screw-on tip (the equivalent of the Victor 2-TEN tip – Victor part # 0311-0485)
i)one might also want a size 3 and maybe a 4 (Gentec 883TEN-3 & 883TEN-4) or (Victor 0311-0486 & 0311-0487)
a)Another elbow tip all in one option is the Uniweld 17-2 all fuel brazing tip (one might also want the 17-3 size)

[shiggy]

Thank you, Doug. I appreciate you taking the time to do this. I will do my searching and ask questions as I have them.