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Torch questions for a public teaching studio

Hi all,
I’m a working and teaching metalsmith, with one of my roles being (very part-time) managing the metals studio of an arts center. Our soldering setup is a pair of acetylene B-tanks with Prest-o-lite regulators/hoses (they came in an all in one kit, purchased approximately 10 years ago).

We have a wonderful long-time instructor who has been having issues with the torch:
–gas flowing back into the regulator at one point, which was a faulty valve on an old B-tank we received, but supposedly this is still happening with other tanks we’ve received since though I’ve never personally observed it. Seems like the main/only cause would be the tank not being shut all the way? Are there any other causes for this? Specifically, she bleeds the tank, gauge dial goes to E, she loosens the pressure valve, and then when coming in a week later for her class (limited class offerings right now), finding that the dial has crept back up.
–“flames coming out the bottom of it” I think where the torch tip screws into the hand piece, which would just be a case of the tip not being all the way screwed in? Any other potential causes for this?

I’m trying to balance being sure that the studio is safe, and also that the instructor feels comfortable. She apparently is so nervous about acetylene that she doesn’t use it in her home studio anymore, and only uses disposable MAPP gas canisters there, so part of the issue certainly seems like anxiety, but I don’t want to brush aside any legit safety issues. One concern of hers is the age of the hoses/regulator. Is there a general guideline for the lifespan of an acetylene regulator and hoses? We also have a large oxygen-acetylene casting setup which unfortunately hasn’t been used for a few years and she’s concerned about those going bad and being a safety risk as well (I’m less certain of their age, but I think the casting setup got new hoses/hand piece around 10 years ago as well).

One main option that she seems to feel good about is replacing the regulators/hoses. I had first wondered about a two-gauge Smith, but turns out she’s never had a two-gauge torch and I wonder if that unknown factor would increase anxiety. But also, they’re a bit pricy! I’ve personally used a Prest-o-lite for almost 20 years without any issues, so I suppose I’m inclined to stick with what I know. Does anyone have any recommendations for another dependable, reliable torch/hose kit that might be any better and good leads on best prices?

Thanks for sticking through the rambles! Trying to find a solution that keeps students safe and fosters a comfortable learning environment, makes our instructors feel safe and valued, and makes our administrators happy by not breaking the bank!

I would suggest that if both you and the other teacher are uncomfortable around torches of any kind that you contact your local welding supply company and ask for someone there or someone they can recommend who is an expert to take the time to educate you both on the types of gasses used, torches, regulators, and just a general overall education in how to trouble shoot and safely handle these things. If your school is in a facility that has natural gas I would recommend that you look into using Nat Gas with oxygen. Not only very affordable, but easy to set up and as far as most long time professional non ferrous metal smiths are concerned the best option for being able to control flame sizes and temperatures. With that kind of control you can make soft reducing flames to avoid oxidation of metals while annealing and melting metals for casting and ingot pouring as well as using the hand holding the torch to loosen or tighten the flame to direct solder flow. Best wishes and good luck on solving your issues.

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Jo…I agree that the OP needs to get some current information about torches and torch safety. I am happy to have acetylene and any other high pressure gas out of my shop. Assuming that you are talking about street pressure NG and O2 torches and not NG concentrators, please tell me more. I am not ready for a NG concentrator, but would love to try street pressure NG and O2 or air and see if I can do what I do with such a torch setup. I just need to know what torches will do this. Thanks…Rob

All of the shops I ever worked in ran on Nat gas and oxygen with the occasional hydrogen torches for platinum casting and hydrogen water torches for fine soldering and fusing work. We never used a concentrator. City gas has plenty of pressure. Acetylene burns too hot and too sharp of a flame and the soot and carbon contaminate platinum as well as some gold and silver alloys with noble metal in them.

I have been looking at various torches for a long time that say they are NG and air or O2. They are often in the art glass world. I can’t really find one to try. I have experimented with my Meco and Hoke torches on street NG and O2 and haven’t been able to get the kind of flame that I want. I don’t know if this is the torch or my NG pressure. We live in the country at the end of the NG line. Thanks…Rob

There are a ton of torches out there that are suitable for natural gas. Hoke, Meco, Meco Midget, Gentec Casting torch, Swiss Torch, Little torch, Harris Melting torch, etc.
I personally use a vintage NCG torch that’s probably at least 80 or more years old.

It’s probably your local NG pressure. When I worked in the NY diamond district, back in my youth, all the shops ran NG without concentrators, or flashback arrestors for that matter. The Hoke torch was the standard of the industry, though that was when they were still made in the US. Today NYC regulations require arrestors and thus concentrators, because street pressure is too low for flashback arrestors to work correctly, or so I understand.

Unfortunately, switching to natural gas isn’t an option for the studio as we don’t have any NG lines running to that part of the building.

I’ve been working as an artist and educator and using acetylene for twenty years, so I consider myself to be pretty knowledgeable but currently stumped on my instructor’s issues (she’s been teaching and silversmithing professionally for more like forty years, so despite her quirks, she’s very knowledgeable as well). This morning I bubble-tested and cleaned all the torch tips and didn’t have any issues with our torches, so it’s difficult to troubleshoot a problem I’m not seeing.

As part of their contract with us, our gas supplier delivers our acetylene B-tanks to the studio, screws on the regulator, and does a safety check with each tank delivery, so they’re not seeing any causes for concern either.

Elliot…That is my real question and maybe I wasn’t clear in my reply to Jo. What I have heard or read is that there are torches that will work on street pressure NG and O2. I think that, in reality, either street pressure in some areas is higher than my 1/4 psi or they were really using NG concentrators as you describe. Sorry for my confusion. Thanks…Rob

Running a torch on plain un-boosted ng works best with ventilated tips. I first found ventillated tips in glassworking supply. The Paige tips used on Meco Midget, Hoke, and others are ventilated tips and make the street pressure gas work very well. a booster is kinda like frosting on a great cake. the new tips from paige are machined rather than assembled and are far better.

Thanks, I have experimented with street NG and O2 and couldn’t get a real satisfactory flame. I now have Paige tips and have been planning to try again. Stay tuned…Rob

When I took classes at our local community college, the torches ran natural gas and compressed air. There was a giant air compressor (65gallon) which was piped to a big standing bench. The torches were primitive but were good enough to teach the basics of working metal.

Rob and I have discussed torches quite a few times and we have ended up with the same gear for different reasons. Rob’s concern for having fewer pressurized cylinders in the house is a real concern. I am a nut about safety in the shop too. I don’t have the same concern about a “B” tank of acetylene in the shop. I have other reasons for going with a Little Torch instead of the Prestolites that we learned on. Propane and concentrated O2 has been a good solution. What I haven’t heard yet, and I may have missed it, is why suddenly change to Natural Gas and O2. Presumably it is safer than acetylene. But is it safer than propane? And it seems to require some new equipment that is proprietary. Is there a reason other than convenience?

Don

According to Inspectopedia, the on-line “Encyclopedia of Building & Environmental Construction, Diagnosis, Maintenance & Repair,” a standard natural gas operating pressure is 0.25psi or 7 inches water column. That isn’t enough to run a torch, AFAIK. Maybe it was higher years ago. I’m sure you could find out the line pressure in your area by calling the utility. I guess there’s a reason they sell those NG concentrators. I looked into that when I switched from acetylene to the 1 lb propane tanks and O2 concentrator, but the NG concentrator was about $600, if I remember right and I have gas at the curb, but the house isn’t plumbed for it yet, so there would be that additional expense. We thought we’d get a gas stove and gas dryer when gas came to our neighborhood, but ultimately decided against it.

To the OP, I would just agree with what Jo said about getting a welding supply to look at the torches. Sounds like there is a leak at the handle of the acetylene torch and perhaps a bad regulator. These do go bad…usually the rubber diaphragm, but perhaps a spring. The welding supply can rebuild it for about $100 or sell you a rebuild kit (I’m not doing that rebuild myself, tho’). A new acetylene regulator is not that expensive, the cheapest about $30 and from there running up to maybe $100. Having torches that don’t work right in a public facility with students fills me with fear and trembling and I would get those torches looked at right away before using them. I’ll also add that a friend who taught adult students at a Gem and Mineral Society workshop tried out the small butane torches which you can get at Home Depot for about $35 (the Bernzomatic) and he and the students loved them for small projects. Bear in mind that some teachers also just use a standard propane-air torch on silver. To me it’s a little awkward to hold that 1lb tank in your hand, but they swear by it and probably a lot of Native American smiths used them after they stopped using the gasoline blowtorch (1930’s?) until they got more sophisticated… -royjohn

Though my knowledge on this specific topic is truly lacking, I simply love the exchange of ideas from different perspectives by people who have practical - rather than theoretical - knowledge. This forum is Ganoksin at its best.

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Hi royjohn,

Bear in mind that some teachers also just use a standard propane-air torch on silver. To me it’s a little awkward to hold that 1lb tank in your hand,

I mostly use a Smith torch (oxy/actetylyne) but, if I’m just in the shop for a little while, or doing mostly non-torch work and don’t need the precision of the Smith, I’ll sometimes use a plumbing torch. I actually have one with a hose that attaches to the tank, so no need to wield a 1lb tank. It’s quicker because you don’t have to adjust the regulators, and the added bonus is that you don’t have to bleed lines afterwards.