air acetylene?

A guy showed me his air acetylene setup. B bottle, Goss regulator, Goss torch & tip. He cracked the tank and the gauge on the regulator showed pressure. Then he shut off the regulator and within like 5 seconds the gauge reading dropped to zero. The gauge was not calibrated in psi, rather it was calibrated in percent full.

I figured it was a pressure gauge labeled to sell to guys who don't know any better. Further, I figure there's a leak somewhere in it because the gauge reading bleeds off so quick.

With the knurled diaphragm screw threaded all the way out, when there should have been zero output pressure, when I cracked the cylinder and opened the valve on the torch I could just hear a very faint hiss.

What do you guys think? I don't know much about air/acetylene rigs but now I'm looking for one to sweat a bunch of copper tubing.

metalmagpie

Soaped everything up and found it. (After I bought it and brought it home, having negotiated a discount due to the questionable condition.) It was just where the regulator threads onto the B bottle. A nip with a 12" Crescent and no more leak.

There isn't a gasket between a CGA 520 nipple and the tank valve is there?

metalmagpie

No, there is only a few tanks that use gaskets, CO2 is one. I also have an Argon Fluorine mix that uses teflon seals.

another leak location

Another place to check on 'B' tanks is the stem packing.

With the tank valve off, loosen and remove the stem packing nut. There is a brass sleeve that compresses the packing material and creats the shaft seal. These tanks are a commondity, and are just exchanged without regard to manufacturer. some have been in use for a VERY LONG TIME.

The tank fillers do not often check the packing condition. If the paking bushing is flush with the top of the valve body, remove it and add a turn or two of round teflon gasket packing. If you cannot find any packing, you can pull off a foot or so of teflon pipe joint tape, double it over a few times and roll it into a round string like form and use that. It wont take to much, but after compression the brass sleeve needs to be proud of the valve body.

I used prestolite air-acetylene torches for 40 plus years, and still prefer them over propane reardless how expensive they are to operate. The new 'turbo torches' crank out enough heat to braze 3" copper pipe with the large tips.

paul

metalmagpie said:

Soaped everything up and found it. (After I bought it and brought it home, having negotiated a discount due to the questionable condition.) It was just where the regulator threads onto the B bottle. A nip with a 12" Crescent and no more leak.

There isn't a gasket between a CGA 520 nipple and the tank valve is there?

metalmagpie

Click to expand...

metalmagpie said:

Soaped everything up and found it. (After I bought it and brought it home, having negotiated a discount due to the questionable condition.) It was just where the regulator threads onto the B bottle. A nip with a 12" Crescent and no more leak.

There isn't a gasket between a CGA 520 nipple and the tank valve is there?

metalmagpie

Click to expand...

Good job negotiating. No, there is no gasket. Just tighten till it stops leaking. SOP. Always check when you remount the regulator. Eventually the regulator stem may get so beat up that it's hard to seal and then you replace it. My regulator is like 50 years old and the stem has been replaced but once.

macona said:

No, there is only a few tanks that use gaskets, CO2 is one. I also have an Argon Fluorine mix that uses teflon seals.

Click to expand...

Interesting that your set-up uses a Teflon washer, Teflon being a perfluorinated polymer which is subject to degradation when exposed to Fluorine. The concentration of F in your mixture must/should be extremely low.

FWIW, we had a tank of Fluorine in our chemistry lab at school that someone put a Telfon seal in, between the outlet and a hose running to an experiment. The Teflon seal was destroyed in short order, later to be replaced with something that is readily passivated by the Fluorine- lead washers.