Acetone spitting and Flashback

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hii guys ...am new to the site and new to welding. I am into EHS and during the course of an investigation stumbled into this issue.1. During oxyacetylene welding, what are the chances of an acetone-spit causing a flashback? Should both be treated as separate incidents or as connected. (The cylinder which was being used when flashback occurred had a coupla acetone spit complaints too.)2. Does the quantity of acetone filled in the prorous mass vary appreciably based on the type of porous mass used in the cylinder? (Asking this question to determine whether the cylinder-which was of a type that was just introduced- might have been overcharged with acetone, and hence resulted in spitting.)Hope you guys would be able to throw some light on the issue.
Reply:only time ive heard of a cylinder spitting acetone  is if it is laid down and used without an adequate period of time standing vertically to allow the contents to re-settle. was this the case?
Reply:No, it was not laid down. in fact couple of cylinders in the same batch have displayed the same problem. thats why I am interested in the filling aspect of it.
Reply:I am no expert on the subject of spitting or flashbacks but believe drawing acetylene at too great a rate can also cause spitting. I could also theorize about the other but don't think that would be of use now. By flashback, you do mean the recession of the flame into the torch only, right? By EHS, do you mean Environmental Health & Safety?
Reply:Oldiron: Yes on both counts.The chances i'm looking at right now are1. the spit Acetone reacted violently with the copper in the torch and caused a blowout, which the technician mistook for a flashback. MSDS of acetone says that it can react violenly with copper, silver etc.2. the spit was caused by an acetone overfill. (New type of cylinders with differnt porous matl was used)and thanx for that tip. I will look into that too. Btw, how much would be too great a rate?P.S- should say that getting to an accident site 48 hrs after an incident and searching for evidences is quite taxing!!
Reply:Talk to your LWS and they will be able to tell you what the maximum rate you can draw per cylinder size.  I haven't had to do those calculations in a long time and don't want to give you bad information.2 Trailblazer 302's2 HF251-D1'sDynasty 200DXLincoln Powermig 140CHypertherm Powermax 30Airco Torches out the a$$
Reply:It could be caused from an overfill, I suppose or a damaged honeycomb in the tank.  The only other way I see is that the tanks were used on an incline or laying over.Esab Migmaster 250Lincoln SA 200Lincoln Ranger 8Smith Oxy Fuel setupEverlast PowerPlasma 80Everlast Power iMIG 160Everlast Power iMIG 205 Everlast Power iMIG 140EEverlast PowerARC 300Everlast PowerARC 140STEverlast PowerTIG 255EXT
Reply:Originally Posted by winnOldiron: Yes on both counts.The chances i'm looking at right now are1. the spit Acetone reacted violently with the copper in the torch and caused a blowout, which the technician mistook for a flashback. MSDS of acetone says that it can react violenly with copper, silver etc.2. the spit was caused by an acetone overfill. (New type of cylinders with differnt porous matl was used)and thanx for that tip. I will look into that too. Btw, how much would be too great a rate?P.S- should say that getting to an accident site 48 hrs after an incident and searching for evidences is quite taxing!!
Reply:You'd be hard pressed to get spitting during acetylene welding that was caused by the draw rate.  1/7 the cylinder capacity per hour is where you can begin to draw liquid acetone.
Reply:I went and looked at three MSDS from different sights. The word 'copper' wasn't in any of those. Suggested draw off rates are set by the CGA, Compressed Gas Association. Current rates are set at 1/10th I believe, down from the old 1/7th. However they are the go-to experts on that.
Reply:I agree with Sandy about the recommended draw rates, but don't know what conditions are required to get spitting to really happen. My untested/unproven opinion (based on knowledge of chemistry and general welding  stuff) is:Acetone is much less reactive than Acetylene. Liquid  going through a hot torch will vaporize and is likely to blow out the flame as makoman says, but shouldn't be able to react chemically. For a flashback to occur, either the tip needs to get so hot that it causes pre-combustion within the tip, the oxygen vs gas ratio needs to rise to change the burning rate or cause actual detonation, (in a neutral flame, there's only enough O2 to combust the Hydrogen and part of the carbon; the air outside the flame does the rest); something needs to restrict the flow of gases below the mixer, especially the fuel; or a spark has to shoot into the tip to cause the pre-ignition.What was the result of this occurrence? Was something  or someone damaged?BTW, to prove my point about the reaction of acetone, you could try heating a long, thin copper tube fitted at one end with an orifice just large enough for a hypodermic needle, or perhaps having the orifice and a rubber tube bringing air into the copper tube. Heat the tube towards the far end (with a small airflow for the second method) and inject a small amount of acetone into the copper (or rubber) tube. Nothing significant will happen. If the copper is heated to red hot and dropped into some acetone, it won't have time to even reduce much (if any) of the oxide film which developed while heating.
Reply:I had a cyl. do that last year. It was a refilled cylinder standing up in the truck. I had picked it up about a week before and this was the first time I had used it, I cut for about thirty seconds and then it started spitting acetone. All it did was blow the flame out. At first I thought I had gotten the tip too close to my work, but when I tried to relight the torch I realized the problem.I took the cyl. back and told them what was happening and they replaced it with another and I've had no problems since.Also might add, that in thirty years welding that was the first time it ever happened to me.Trailblazer 302Hobart Stickmate AC/DCLincoln SP 135 TSmith torchSpoolmatic 30A
Reply:Originally Posted by SupeYou'd be hard pressed to get spitting during acetylene welding that was caused by the draw rate.  1/7 the cylinder capacity per hour is where you can begin to draw liquid acetone.
Reply:Sandy: This is what the acetylene msds says :INCOMPATIBLE MATERIALS:Oxygen and other oxidizers including all halogens and halogen compounds. Forms explosive acetylide compounds with copper, mercury, silver, brasses containing >66% copper and brazing materials containing silver or copper.Source:http://www.weilerwelding.com/MSDS/Acetylene.htmli think I mentioned it as acetone msds. Sorry for that!Shortarc: Blow out as in extinguish the flame without even a sputter ?Oldiron: Luckily only the torch was damaged. Many thanx, all of you!!  Guess i'll look into the welding practise for clues on the incident and treat the acetone spit as a parallel issue.
Reply:Acetylene IS incompatible with copper, BUT acetylide crystals form VERY slowly.Piping acetylene in copper pipe will make for an extremely dangerous situation, -in time-, but not in seconds.  Metal in the solid phase can only react on the surface, so with limited surface area (and therefore limited chemical interaction), things happen slowly.  Think rust . . .Anyway, its not the acetone that could react with the copper in the torch tip, AND, torch bodies are already designed with a bronze alloy that will not react with acetylene, and torch tips only get mixed gases, where this isn't a problem either.
Reply:Originally Posted by winnSandy: This is what the acetylene msds says :INCOMPATIBLE MATERIALS:Oxygen and other oxidizers including all halogens and halogen compounds. Forms explosive acetylide compounds with copper, mercury, silver, brasses containing >66% copper and brazing materials containing silver or copper.Source:http://www.weilerwelding.com/MSDS/Acetylene.htmli think I mentioned it as acetone msds. Sorry for that!Shortarc: Blow out as in extinguish the flame without even a sputter ?Oldiron: Luckily only the torch was damaged. Many thanx, all of you!!  Guess i'll look into the welding practise for clues on the incident and treat the acetone spit as a parallel issue.
Reply:Acetylene IS incompatible with copper, BUT acetylide crystals form VERY slowly.Piping acetylene in copper pipe will make for an extremely dangerous situation, -in time-, but not in seconds. Metal in the solid phase can only react on the surface, so with limited surface area (and therefore limited chemical interaction), things happen slowly. Think rust . . .Anyway, its not the acetone that could react with the copper in the torch tip, AND, torch bodies are already designed with a bronze alloy that will not react with acetylene, and torch tips only get mixed gases, where this isn't a problem either.
Reply:Acetylene can be safely drawn off at 1/7 total bottle volume an hr, Its easy to exceed this when using a rosebud for heating. Acetone will turn your flame green and spit alot, plus it STINKS..Im pretty sure that "Yellow" copper which is commonly used in welding equipment is compatible with acetylene; However "Red" copper which is used mostly in piping is not.
Reply:When ever you buy a tank of gas you are supposed to crack it open slightly to blow out any dirt etc.,.Now if you crack it open and you see liquid acetone spit out you should take it back and exchange it for a good cyclinder.The small type "C" portable cyclinder is prone to turning to acetone.What is bad is if you have the latest one way check valves in your hoses acetone will immediately ruin the o rings in the check valves and causes them to swell up and make thetorch unusable. You will have to buy new check valves.You are supposed to let Actylene tanks sit upright for 30 minutes prior to using if the tank has been laying down.Plumbers are constantly abusing portable O/A tanks. Throwing them in the back of a trucks etc.,.  You are supposed to transport only with the guages removed or transport with the safety device cover locked on.AWS certified welding inspectorAWS certified welder