As part of my other thread dealing with a stuck hydro pin, I have reached the end of my rope borrowing torch stuff. I help others but when I need a torch, I get 2 empty bottles and told "just fill them". Time to buy and it's been 20y. So here is the thing, I don't do mobile stuff often, and obviously don't use a torch that much anyway. I'm also HVAC so I want to delete the borrowing of a small rig for that work. What I am thinking on is about a 150cf O2 tank, then a smaller O2 tank with it. Obviously as pressures drop, this is not a full fill but can kick the can down the road since 20cf fills are high. As for Acetylene, I'm mostly in the boat to just run LP for now? I've run it, both for heating and cutting. Heat work was for either shrink fitting or heat treating. It was clean and ran perfect. Cutting was obviously slower but I don't use torches for major cutting. If I ran into that, I would get an Ace bottle. For LP, I can fill off the big tank, and I want to charge my little 16oz bottle and I think I can easily braze AC stuff with one, and the cleaner flame I think will make it all the better. thoughts so far? I've found TSC does a new/exchange deal but new tanks are STUPID high! Used, the welding supplies local bend you right over. I don't know where else to go for O2, but because of this, seems like LP makes even more sense. Locals want a 'maint fee' plus the fill. Onto outfits. because I rarely use, I am leaning towards some knockoff gear. People want stupid price for Victor gear. I don't even know which I would use most, but I do know I need LP setup, rosebud, braze tip, and would be nice to get some knockoff gear that adapts to standard Victor or other thread? I recall these guys play games with this so things are never compatible? Some stuff at Harbor Freight has come a LONG ways. Like wrenches that out perform SnapOn. But playing with flame gas, I don't know other than if it sucks that bad, lawsuits would surely be in order so I would think it has to meet some regs? Or other kits, I don't know, but I need something yesterday!
Torch setups can be expensive, especially if you don't use them often. My best advise is to get what a good welding supply store in your area has. It may be expensive but you want them to still be there in 10 years. The brand of my outfit is SMITH. I think they are the best but there are other good ones out there. I would steer clear of a HF one. I have used one before.
Keep an eye on marketplace, I have seen some good setups come along with bottles cheep. I bought 2 setups just for the bottles and sold the rest making the bottles that much cheeper. Check the neck rings blank are good local supplier not so good, could be leased bottles.
One thing to think about buying used tanks, is make sure that you can get them filled or exchanged at your local supplier. I worked for a man that was going to be smart and get them cheaper. He bought a bunch of tanks some where but the local welding supply wouldn't exchange them because they were not theirs. He finally found a place about 40 miles away one way that would fill them. I didn't think it turned out that good of a deal. Just be sure you will be able to get them filled where you were hoping to. A lot of times the lease can be transferred from one owner to the next.
I standardized on Airco/Concoa for my cutting torches. tips all interchange, have a good amount of different sizes built up over the years.
You don't need to spend a fortune for a small acy/oxy set. Here is an example of a small one and larger ones are available to. They are quite handy because they can be carried wit one hand by an average person. I watched steel a suplly outfit use one to trim new I-beams in a new basement and it was fast because he didn't need to use long hoses like I have in my shop.
A welding supply should have a Victor knock off of decent quality. A good quality torch set will last for decades. Always back off the adjusting screws on the regulators before opening and open cylinders slowly. Victor are the most common and you can buy tips and accessories everywhere. You could try other torches to see what's the most comfortable to you. I much preferred Purox torches but Esab in their stupidity discontinued them. They also bastardized some of the the Victor torches that were very popular. Almost like somebody at Esab just had to put their spin on the torch to make it different than original Victor. I think you're right to get bigger cylinders. The tiny tanks are much more per cubic ft. and don't last long. They are good in tight spaces or if you have to haul a torch up stairs or something. Some sets can be hooked up to larger cylinders. You don't want to try filling from a larger cylinder. It could end up bad! To use propane you just have to change tips or buy a propane kit. You can braze with propane but can't weld with propane. Propane has specific rosebud heating tips too. You have to be careful buying used cylinders. Some are actually stolen lease tanks that can't be refilled and the welding supply will confiscate them. I have seen some good deals on legit customer owned cylinders. Some welding supplies sell cylinders and some only lease them. You'd have to compare the costs. If you buy you may have to pay a hydrotest test fee every 5 years or 10 years depending on how often the specific cylinder requires testing. I think most nowadays are 10 years but have seen a lot with 5 year test dates. The advantage of buying, if you can get them easily filled locally is you don't keep paying a lease year after year that keeps going up in price. Always use at least a shade 3 lens when cutting if you value your eyes. I know some that don't and I cringe. I can't see my soapstone lines without goggles.
Those would be perfect. I don't cut much, but sometimes I'd love to be able to heat something
The local welding supply store where I get my big tanks exchanged sells the small kits like the one in the image, and will exchange the tanks when they are empty. If you buy them on ebay or used somewhere you may have a problem getting them refilled/exchanged. I tried using propane many years ago and was disappointed in it compared to acetylene. Especially when using a rosebud torch to heat anything big.
You need big cylinders for a rosebud. Propane doesn't have a withdrawal rate that you need to be concerned with like you do with acetylene so you can use larger rosebuds. Propane has more BTU's than acetylene and propane needs more oxygen than acetylene. Acetylene has a higher temperature in the inner flames and the heat is more concentrated. Propane has a higher temperature in the outer flame so is better for heating a larger area. Because you can use a much larger heating tip with propane it is better for heating big or thick sections. Was hard to find brochures on the huge oxy/propane heating tips but finally found a good comparison sheet for Smith/Miller heating tips. Compare the BTU's of the largest oxy/acetylene tip and the largest oxy/propane tip, almost triple the BTU's and then there's propylene (in-between acetylene and propane) tips up to 830,000 BTU's. There are other oxy/propane/propylene heating tips that are even bigger. They are a modular design so you can pick the heating head and the length of the tube. They can be 4' or longer with the heating tip almost 3" in diameter. Be aware you need large cylinders and lots and lots of oxygen for the huge heating tips. https://contenthub.itwwelding.com/api/public/content/miller-electric-mfg-llc/spec-sheet/PIM/d330d4-ge28-0.pdf
Those tiny cylinders wouldn't last more than a couple minutes for heating and you couldn't really use a heating tip because you'd withdrawal the acetylene too fast which would draw the acetone out of the cylinder. Acetone is what keeps acetylene in a safe stable state. If it's gone you have a really good chance of creating a bomb!
Something I need to dig into. Are you saying there is a safe withdrawal rate for a given cylinder volume? I would likely never need to get to extremes of anything with a torch, at least in the short term. here is something I found from a shade tree dude on "the internet", is acetylene is far superior for things I might need the torch for which is unsticking bolts, or IE unfuking situations similar. Basically spot heating like I'm about to do to try to unstick and stuck pin. Honestly, I can see the acetylene temp being helpful, but we are pumping the BTUs to glow an area of about 1x3". I've used LP for heat treating and it was nice and controlled. For this, I was just going to use a cutting tip. A rose is prob more cost than it's worth in such a small area, and I may well move right to cutting. the cowboy doing the vid was all about that acetylene, even running the cost matrix, but I think it's smart to have gear to run either! Sometimes you are in a pinch and everyone one has a 20# LP around. I want to use it to exploit the cleaner and cooler flame for HVAC! I want to do a little horsing to see if oxidation is better or worse inside the weld without purge gas.
Can't help you on bottles except using propane over acetylene, which I probably wouldn't do. I picked up a torch set at harbor freight and couldn't be happier with it, used it a ton of times and it's perfect every time. I even bought the bigger torch and 50' horses but still use the smaller torch that comes with the set and the short hose as I typically do small jobs and just load up the tanks and drop them right on top of the job. Monday I'll be doing quite if bit of work so I'll be busting out the 50' hose but I prefer the smaller torch still.
I don't know about welding supply houses everywhere else but here several rebuild torches and regulators, I would imagine most do, so if you by something used that may be an option.
The link below explains it pretty good. To use a large acetylene rosebud it's recommended to manifold 2 large cylinders together but a lot of users don't. When I worked in technical support for welding sales for a large industrial supply one of the branch managers got really mad at me and even called my boss to complain. I refused to give him a part number for a high flow acetylene regulator his customer wanted. Apparently the regulator his customer was using was plugging up. He wouldn't tell me what rosebud his customer was using or the size of cylinder. I couldn't in good conscience tell him how to potentially blow himself up! My boss was a little upset until I showed him an article I had found that explained it. The article even mentioned an inexperienced sales person selling a rosebud for too small of cylinder and not knowing the danger. The plugged regulator quite possibly saved his life. What was plugging the regulator was the sticky liquid acetone being drawn out of the cylinder. You have to be drawing a lot of acetylene or using way too small of cylinder to draw that much acetone. A large cylinder that is near empty could also cause it. If the acetone is drawn out of the cylinder the remaining unstable acetylene is essentially an unpredictable bomb! Many welding welding supplies sell acetylene by the actual volume in the cylinder rather than a set price. A set price can rip some customers off. The amount of acetylene is based on how much acetone is in the cylinder. Cylinders are weighed to measure how much acetone is remaining. If it gets too low they either scrap the cylinder or add some more acetone. The cylinders are heavy because they are also filled with a porous material that absorbs the acetone. It keeps the acetylene stable. Acetylene cylinders have to be used in an upright position so acetone can't run out or flow toward the valve. If the cylinders are laid on their side, they should be stood up for 4 hours or so (depending on size) to let the acetone flow back down. https://www.harrisproductsgroup.com/en/Resources/Knowledge-Center/Tech-Tips/Tech-Tips-OLD/What-is-the-1-7-acetylene-rule
Welder Dave , I appreciated reading your last couple post. I never heard all that explained that well before.
Thanks. There's a lot of mis-information and a lot of people just aren't aware. Acetylene is safe when used properly but is dangerous if used the wrong way. I also took a course on propane so I could fill cylinders. I am shocked that anybody can buy a propane tank and get it filled without even having to read the safety precautions. Propane is basically a boiling liquid inside the tank at that's what gives it pressure. If it leaks liquid can cause severe burns because it boils at a low temperature. There were pics. of exploded tanks in the course I took and they mentioned someone had burns over 80% of their body from an exploded tank. It's very important not to fill the tanks over 80% full to allow for expansion.
Did not know about having to have the bottle upright for a few hours when it was laying over, good to know. I did know not to use it on its side.
I will admit that I'm having to dust off the chemical engineering to understand it! Seems Acetylene as just a compressed gas can self decompose with an exothermic reaction, even without an oxidizer. It is considered "shock sensitive". As well, it has a highly positive, not negative enthalpy of formation. As a crude example, if you shoot propane liquid straight from the hose, it will freeze anything due to the negative enthalpy, meaning it absorbs heat to vaporize. Unchained release of acetylene would create a heat wave with no spark. Anyway, the acetone had me confused, but starting to make sense. Consider this concoction no different than dissolving CO2 in water or beer. Let's go with beer. You crack a cold one and there is a release of CO2, but much of the CO2 stays dissolved in the liquid and would just slowly release in the air if just sitting there. With a clear glass, you can see it. A bottle of acetylene works this way in acetone as it also acts like a molecule insulator and ensures it can't all release instantly. This is why there is a limit to CF extraction per tank volume. In theory, temperatures and agitation would likely assist in higher rates, but I'm real sure there are buffers in place. All interesting stuff I didn't even know! It at least helps me with some of the myth vs reality like having a tank on it's side. No way that is going to do something to the contents in transport, but absolutely do not try to use it on it's side! You will certainly have acetone spewing out!
I do some educating on LP as well as the physics side of refrigerants. Mostly to younger techs or high school. LP is not technically boiling in a tank all the time, it hits and stays at its vapor pressure at a certain temp. Grab any tank you want, as long as there is some liquid in it, measure that pressure, reference that to the PT chart, and I guarantee the temp in that chart is what the contents are at. The 80% rule is overly cautious but most tanks by design, can't be over filled. Technically, filling should be done by weight, not gallons because of the volumetric delta T. However, this is accounted for with LP delivery. You guys ever notice you can get more "gallons" in a tank in winter? It's due to the density difference as a liquid. And this is partly is why the 80% rule exists. Nothing will blow up at 85%, but the worst situation is filling in the cold, then warming the tank. Why? Remember I just mentioned the volume change with temp! It's not just the gas at the top, but the liquid volume that will grow! You can calculate it and realize you could normally push to 90% without issue, BUT it's a fuel gas, we don't push limits! LP has a low vapor pressure, relatively speaking. When I teach this stuff, I always use WATER because people understand it. I ask "what temp does water boil at?" If anyone here says "212F", you are dead wrong! Why? Because my question was incomplete! I did not say at what pressure! I assure you I can make water boil sitting on your counter top, with no heat! I install water in a vacuum vessel and watch as the water turns to steam, which is what we call water as a vapor. I can also increase the boiling point! How? go look at your radiator cap in your equipment? they are usually 1 atmosphere. BTW, all of this is exactly what HVAC refrigerants do! Believe it or not, LP is an OUTSTANDING refrigerant! Not only extremely low ozone depletion potential, but really good vapor pressure, latent heat, etc. Only real issue is the bomb! BUT, if not aware, LP is actually a component in many refrigerants and is also flammable.
It wasn't too long ago that LP tanks didn't that have overfill protection devices in them. I may be wrong but it is my understanding that if an lp tank is not upright liquid lp cannot exit the tank. I'm disappointed that acetylene tanks don't OFP devices in them. When I was in high school shop in the 1950's we were made aware of the porus media in acetylene tanks and the danger of trying to use one unless it was in an upright position for no less than 4 hours.
I need to learn more about this media in the tanks, but as it stands for me right now, consider a Coke exactly like the Ace bottle. If you put a Coke can on it's side, do you have upright it and wait? Acetylene is literally dissolved into the Acetone just like CO2 in Coke. I'm just super curious the process to both fill and refill these things! That is a job I would not want, and I'm honestly pretty surprised we use such a lethal concoction. But I don't hear of too many boom booms, so the safety stuff must be working. Just reaching into my aerospace sector, airplanes use several strategies, but only AFTER boom booms have happened....lol Foam in tanks, inerting techniques like N injection, etc.
I toured a fill plant. Acetylene is filled at about 50 PSI otherwise it would take way too long. I questioned how they could fill at 50 PSI and not have it explode. All the piping is extra heavy wall and has to be welded (x-rayed) connections except for regulators or shut off valves and the cylinder connections. The piping has to be small diameter. I can't remember the size but I think 1/2" or maybe 3/4". Very strict protocols for filling acetylene cylinders. We couldn't go in the room where the acetylene generator was where they mix calcium carbide and water. The workers couldn't wear anything with metal. They fill up to 6 cylinders at a time. The cylinders are weighed while being filled based on the amount of acetone in them. They are also sprayed with water to keep them cool. It still takes a couple hours or more to fill the larger cylinders. I think the largest cylinders can take 4 hours and they can only fill a couple at a time. There are a very limited number of acetylene fill plants because of the residue left after the process of making acetylene. It's a sticky kind of paste and is very hazardous waste. Needs specific facilities just to dispose of it. Not positive but I think they have to keep rolling it into windrows so all of it can decompose. The tour was pretty interesting. I wish I could remember better. As as for propane, I said it was basically boiling in the tank to simplify it. It creates it's own pressure. In cold temps in can freeze. Not uncommon to use heating blankets or some kind of heating device. I worked at a shop that used propane. They had to bring the 500 gallon tank into the shop one time because the lines froze up. It was bloody cold outside, I think about -40 or maybe colder. Thankfully it was a vessel shop and they had to keep it warm inside unlike another shop I worked at that was just warm enough to prevent the coolant in the radial arm drill from freezing. It did have ice crystals in it though.
Dave, interesting stuff on Acetylene fills! I figured it was dicey. Still surprised we have not found a better gas! As for LP, it can only freeze into a solid at like -300F, but when people say "freeze", many times that is either water contamination, other mechanical factors, OR, the most common is actually that at low temps, the vapor pressure is so low that the boiling rate is very low so you literally can't boil enough in the tank to feed the need! This is where the bigger tanks win, with more volume. And you already know the rules about running with more LP rather than less when super cold. More liquid, is more that can boil off and serve your loads. But it also brings up the matter of liquid vs vapor being served. Many applications use vapor, and remember that negative enthalpy, LP robs heat as it changes from liquid to gas. This just keeps making the tank colder and colder. One of the reasons liquid extraction is a good route, then vaporize with a heat source like forklifts use the coolant system to heat the regulator.
No one has mentioned Mapp gas yet. I've never used it but one of the mechanics from another company I partnered with on a repair job put it on their trucks. Said it wasn't as hot but was good enough for them. They were a fabrication company and said acetylene had just gotten too expensive. They didn't change any of their equipment to run it.
there is another, propylene, but I;m not in the know. The other is that O2 is a game changer in flame temp. Given the extremes I recently learned on Acetylene, I can only think something will replace it.
Acetylene has been around for 100 years or more from what I know, might get replaced, but everything has safety precautions that often get overlooked that Welder Dave explained in all the posts above. I worked in CNR shops in Winnipeg and the whole shop was powered by 4 PSI of acetylene from huge tanks and they were giving us lots of real world examples of what can go wrong and why respect is not earned but instead demanded. Simon C
When I was small Dad had an acetylene generator and a 50# tin of calcium carbide for the generator. Just a larger version of the carbide miners lamps from long ago (but are still available). They just pulled out and salvaged an old 18" natural gas pipeline near me that was either Dresser coupled or gas welded, as suitable arc welding didn't exist when the pipeline was installed.
Mapp uses propane tips or very similar in most cases. The first shop I worked at used Mapp but isn't really used commercially anymore other than what they call Mapp Pro in disposable cylinders like propane cylinders. There are some cutting tips for propane or similar gas that are 1 piece with preheat holes like acetylene but they are recessed and the outside of the tip extends about 1/8" past the preheat holes. The propane in the tank may not freeze but the regulator and smaller lines freeze stopping the flow. We used to have to put a hot plate under our 500 gallon tank in the winter. It just needs enough heat to produce some vapor pressure.
Acetylene is the hottest flame. Many other gases can claim to be better but they aren't. For burning tables or semi-automatic cutting other fuel gases are used because they are much cheaper. Cutting machines provide a precise speed and follow exactly where they're set. It should be mentioned again that propane and other alternative gases use much more oxygen than propane. I like acetylene because the tips are smaller and the preheat flames let you see your soapstone lines and what you are doing easier. It's not used much anymore but there are still some applications that require oxy/acetylene welding. No other fuel gas will provide sound welds because they don't have a true neutral flame with equal parts acetylene and oxygen. Basically other fuel gases would introduce oxygen and impurities into the weld which would create a brittle weld. The outer flame of the oxy/acetylene flame creates a shielding gas to keep oxygen and other impurities out of the weld.
We have a propylene torch in the shop. Switched to it last year from Acetylene. You use about 3 tanks of Acetylene to 1 tank of Propylene doing the same work. And Propylene is cheaper then Acetylene right now. You do have to use it's own special tips, we have a cutting tip and a big rosebud. When you get the rosebud cranking it sounds like a jet engine drag car getting ready to go. Setting up the torch is a lot more finicky then the acetylene, but you can cut throw 3" plate with ease with the propylene. Pretty amazing stuff.
Good info for a way around buying Acetylene. Simon C
How much oxygen does propylene require to do the same amount of work as compared to acetylene ?
I have read that propane setup uses much more oxygen, however I would not use this as a determining factor. Acetylene prices are very high, how much is propylene ?
When comparing the costs of fuel gas a lot of people don't include the extra oxygen required when not using acetylene. I think propane is 2 1/2-3 times more but I'd have to look at comparison chart. When I get some more time I'll try and find a chart. Lots of stingy shops still use acetylene because that's what most people prefer and they aren't doing heavy manual cutting all day long. Nobody uses acetylene on burning tables though or for heavy cutting like a scrap yard would do. The longest torch I ever came across was in an Esab catalogue. I think it was discontinued awhile ago but it was 12' long!! Large tips capable of cutting 24" thick steel or more had a preheat hole big enough you could stick a pencil in it!
From our experience with it we go through pretty much the same amount. At least it there's a difference it has not been noticeable. But the savings for 3 more expensive acetylene bottle compared to 1 cheaper propylene is huge.
One of my hands said the shop teacher said to only crack the acetylene valve on the tank so if something goes wrong you can close it right away. I thought it not required but after hearing all this safety info about it, would it actually be bad to only crack the acetylene valve on the tank?
Acetylene cylinders can be opened a max. of 1 1/2 turns and if the cylinder requires a T wrench it should stay on the valve. I think the tiny square stem to open/close the valve on small acetylene cylinders is ridiculous and dangerous. Hard to close in a hurry when there's an emergency and they also get worn if the valve is tight. Here's a simple chart showing the oxygen ratio's for different fuel gases. Should note that on thick plate alternate fuels from acetylene preheat the plate a lot more because there is more heat in the outer flame. Thick plate often needs to be preheated before cutting and needs sufficient preheat to continue the cut. There's articles on it but they are quite long. Note how acetylene has less BTU's than anything but natural gas but the burning velocity in oxygen is considerably more than any other fuel gas. https://static.thefabricator.com/a/articles/photos/772/fig1.gif
I know of one shop that runs acetylene on their burn table.....no real reason why, they just doo. They claim it's better, but I don't see any difference, not even reduced edge rounding on top when cutting thick (over 1") where the slow travel speed tends to round over the top edge from the preheat flames. They don't use propane anywhere else in the shop (no hand torches) so that could be the real reason.
It also depends if your using it for cutting or heating. Cutting, the flame is small, and your using much more (percentage wise) pure oxygen for the cutting. Heating, all the oxygen is mixed with the fuel gas, and the flame is much larger.
Majority of our torch work is cutting 3/4" or thicker. If it's 1/2" or thinner we use the plasma. Use the rosebud on occasions but not to often.
If you mostly cut 1" or under acetylene can make sense on a burning table because the preheat time is much less. It adds up if you're doing multiple cuts. Rounded corners at the top of the cut has nothing to do with what fuel gas is used. If the tip is too large, too close or travel speed is too slow will cause it. Wrong gas pressure for the thickness could also cause it. The oxygen used by the cutting jet is the same no matter what fuel gas. It's the preheat flames where more oxygen is required if you use other than acetylene.