fire extinguisher leaking

Cannons powered by pneumatic pressure (compressed gas) using a valve or other release.
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hi
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My dad was nice enough to let me have our old FE. I emptied it out and took the top off and noticed that it had 3/4 inch threads on it. I just happened to have a 3/4 nipple and a ball valve, pressure gauge and a threaded schrader valve and a few other fitting, screwed them together and quickly had an air chamber. Everything worked great until it started leaking (which was instantly
) It leaks where the FE and nipple meet. I have tried everything I can think of. I have gone around it about 10 times, literally 10 times, with Teflon tape and tightened it with a pipe wrench as tight as i can and it still leaks!!!! any other suggestions?
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A-98
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well, if you want to get it off...i dont know. but if your never going to remove it, use JB weld. its never leaked on me.

they also have teflon paste, which might work.
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noname
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Dump a bunch of silicone sealant on the male threads and then screw it in. Wait for the whole cure time, then test it. It should be perfect. If it does leak (highly unlikely), you can always wrench it off with a vice and pliers.
allthingsgo2
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Take it to a welding shop and have them put a nipple on it for you.
Im not sure i trust the jb weld
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MrCrowley
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JB Weld = Best thing since sliced bread.

3/4" threads thats interesting....mine had weird threads about 5/8" threads....I had to get <A HREF="http://www.spudfiles.com/forums/viewtop ... 2">Mine</a> welded.
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A-98
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well, if its already threaded with 3/4 then teh jb weld will do nothing but strengthen the bond.

JB weld = sliced bread+canned meat
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If i use the jb weld, do i do it with or without the Teflon tape? I have jb weld and ill try it, but would still like other suggestions before i glue it.
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A-98
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i find that it doesnt work as well with teflon tape.
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MrCrowley
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Use teflon and once its screwed into the FE put JB over the gap between the fitting and the FE...
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rna_duelers
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Use about 20 wraps of teflon tape,and a little grease.Seems to work for me.
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Matheusilla
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The threads in a fire extinguisher have a larger pitch than pipe threads. Use the jb weld (or "steel" epoxy).
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yeah one of the problems is probebly that the threads aren't really 3/4" sort of like how garden isn't 3/4"npt but you can actully use npt with garden hose if you just use lots of teflon or sealent
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spudthug
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ok well first of all u most likely ruined ur fire extinguisher by putting that 3/4 in...it is most definately not 3/4 the 3/4 may fit but trust me it isnt 3/4....second fes are machine threaded and will leak no matter what...pipe thread is 14 threads per inch the fe machine thread is about 22...u do the math the only way to get it stop leaking is to weld/silver solder it...i silver soldered mine because it isnt made for fittings....
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lukemc
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is silver solder the same as soldering copper pipe?
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Fnord
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I had the same problem with some black iron pipe I bought for making a hybrid over the summer. I did some pressure testing and it would leak no matter how much teflon tape I put on it. Then it was like 10:00 at night, and I just though what the hell, and used electrical tape instead of teflon. It never leaked again, even when I pressurized it passed 160 psi.
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