Buying/leasing Oxy/Ace/LP torch bottles and goodies.

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.

Tinkerer said: 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. Click to expand... 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.

John C. said: 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. Click to expand... 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.

fastline said: 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. Click to expand... 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 fastline said: 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. Click to expand... 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.

fastline said: 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. Click to expand... 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.

ThatGuysFarm said: 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. Click to expand... 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 ?

Tinkerer said: How much oxygen does propylene require to do the same amount of work as compared to acetylen Click to expand... 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!

Tinkerer said: How much oxygen does propylene require to do the same amount of work as compared to acetylene ? Click to expand... 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.

ThatGuysFarm said: 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. Click to expand... 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.