Hi fettlers, I am trying to run an express unis France blowtorch. When I tried to loosen the vaporiser I had a crack in the metal arroud the thread and the problem still not solved. Is this crack could be a danger in the future when the blowtorch is running and pressurized?
You mean this? It’s hard to tell from the photo whether that’s a stress crack in the brass or a cavity in the solder of the joint. Either way, it should be repaired. Express blowtorches are usually gasoline fuelled I think? All the more reason to be sure the crack/cavity is repaired than if kerosene were the fuel, which if a leak were to result would present less prospect of danger.
@presscall thank you for your answer. Yes that's the crack. It is not a cavity it is a new crack created when a tried to loosen the vaporiser. I noticed that this crack is in the welding and not in the tank. I think that the tank and the thread are 2 different pieces.
@anass amghar I see, and it means you’ve been unable to remove the component screwed in there? What fuel does it use?
Looking at the crack, it looks like it's only very edge of what look's like a lead solder, it looks like it has a pump to pressurize the torch,and has a burner assembly that is typical of a gasoline or a alcohol torch, Usually on small gasoline alcohol torches, they are usually self pressurizing, i would pump a copious amount of air into the tank and immerse it in water to see if it holds pressure, if there are no air bubbles escaping you have no leaks, then it is only the edge of the solder coming away from the tank
hi @presscall and @mr optimus it's a gasoline blow lamp and no i can't remove the vaporiser screwed. wd-40 has no effect and i don't have another blowtorch to heat it. brutal force twisted the metal and resulted into a crack in the welding. as you can see in the photos the vaporiser moved to the right without unscrewing the vaporiser.
WD40 is only a water displacement fluid. It is a myth that it works as much else. Definitely not a penetrating oil.
On the thread that screw into the tank will have a tapered thread, i have had a stove or blowlamp that has been quite difficult to undo, It's probably the first time it's ever been exempted to be removed in it long life. I would be fore trying any thing else, use a proper penetrating oil and leave it to soak in for a few days, DW 40 can help but as mentioned by snwcmpr is a water displacement fluid
Well said, this misconception is endemic in the UK, always makes alarm bells ring in my head when somebody mentions how they soaked something in 'WD'. Even proper penetrating oils do not free stuck components, they assist further movement once components are no longer stuck. And are better added once the component is unstuck, when capillary action can take place.
hi @mr optimus and @snwcmpr i had the idea to continue to force it with a hammer until the welding tear up and solder it once i replace the wick. i will try the penetrating oil before that.
Please, no! If you have access to a vice, clamp the burner (with packing and remove the burner shroud) and unscrew the tank from it by hand.
Hi @presscall I succeeded by forcing it but not without some damages. What do you suggest about this crack that is yet more bigger ?
@anass amghar Well done! You were right to want to remove the burner because the cotton wick is in poor shape. The crack is in the solder and not the metal of the tank itself, so that’s good news. I said ‘solder’ but it’s unlikely to be lead solder because the heat of the burning priming fluid surrounding it would melt it, or get it very close to melting. It needs a ‘hard’ solder (silbraze - 50% silver would be fine) to repair the joint. The old solder should be machined out and the joint re-made with silbraze.
Update The wire wich the cotton wick was attached is iron. Cotton + rust + 80 year(or more) transformed into a paper pulp. I will replace it with a cooper wire.
@kerophile might have a metallurgical answer. I just go by the fact that manufacturers used brass. They must have had a reason for that, and not using anything else. Copper flakes exposed to heat.
