Trying to locate a recent post comment re: BTU;s ...any help appreciated

Jewelry Discussion
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Hi,

I seem to recall reading a post comment recently that discussed BTU’s…in relation to how much BTU/s would be required to melt X # of ounces of metal (sterling?)…

I have searched the archives, but cannot seem to find it…anyone recall it?..know who wrote it?

I am starting to become curious about the BTU’s and PSI ranges for certain torches/ torch tips…namely the ones I will be using…

I did find reference to the BTU’s for the Oxy/Propane Smith Little Torch and its varius tips, as well as the Oxy/ Propane Smith AW1A Versa-Torch and it’s neck/ tips, on the millerwelds.com website

I was not able to find this info for the ESAB Presto-Lite torch (oxy/ acetylene)

curious and curiouser…not sure what i will do with this information once I have it., haha!

Julie

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I would also love to know this information as I have been fussing with my number three size Smith little Torch tip. It always wants to blow out!

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Hi,
here is some Little Torch info from millerwelds.com

look under
equipment/ oxy-fuel equipment/ oxy-fuel specialty outfits/ little torch/little torch basic outfit, B fittings

and then click on spec sheet

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it says 4 psi for oxy and propane, 1150 BTU/hr

your tip may be blowing out if the psi is set too high…?…

I have been trying to melt about 4 oz of sterling silver with the below torches, and was just curious about their BTU and temp and PSI…dont quite the inner workings yet…

using the Smith Little Torch:
-rosebud tip spec says
oxygen psi-15, propane psi- 10, 6000 BTU/ hr

-#7 tip spec says
oxygen psi-8, propane psi-8, 9200 BTU/ hr

i am waiting to recieve the Smith AW1A Versa Torch, with AT61 threaded neck

  • to use with my Paige MX melting tip
    I do not know the psi requirements, or BTU for the MX tip

…and my propane is on a non-adjustable disposable regulator and i am not sure what the psi on the regulator is…yet…it kinda seems like on or off…not sure if turning the knob affects the PSI…will call Miller tomorrow…

the spec sheets says, using Smith AW1A Versa Torch with their threaded AT61 neck:

(i do not have the below tips…i was just reading this on their website)

(these could possibly be too hot/ too much for my jewelry needs…i do not know…)

-with their 13715, 4-hole tip says
oxygen psi- 38, propane psi- 12, 16,600 BTU/ hr
(i have never used this high of a psi before…)

-with their NE164 single hole tip says
oxygen psi-10, propane psi- 10, 27,500 BTU/ hr

i dont understand it all…but would like to learn…

i think other contributing factors are:
gas types
torch valve size
how heat reflective your surface is
crucible size/ mass relative to melt amount
…

julie

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correction:

Presto-Lite AIR/ acetylene (not oxy/acetylene)

julie

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Thank you! I started looking on their site, but I couldn’t find it so this is really helpful

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Hi,

ok, so…regarding the Smith Miller Preset Regulator (#249-500B for Propane Disposable)

I spoke to tech support at (Smith) Millerwelds.com, and they said that:

  1. the PSI is preset, and that the knob does not adjust the PSI…it is either full open or closed.

  2. according to their information, the preset Maximum PSI is 15 PSI…and that the pressure does drop as the volume in the tank is reduced, but he could not say by how much, or the relationship between the tank pressure and volume.

interesting

Julie

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Forgive me for being slightly off topic, but I just looked at the price for this item on Amazon,$119.99! Just get a regular regulator, which will be cheaper and have a gage on it so you can tell what your pressure actually is and turn it up when the tank is getting low. The SLT instructions have guideline pressures for you. Yes, gage will not show pressures below 3 psi, but you can get them down to 1-2 psi. I use a regulator with a 1 lb tank and it works on the smallest tips on my Hoke, which are smaller than the SLT tips… any welding supply can help you with any fittings that you need. I figured that out myself and bought them on Amazon. The propane and acetylene regulator are the same, so you can use either, if the latter is easier to find or cheaper. -royjohn

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Hi Royjohn,

i did not know dial regulators were available for 1 lb dispisable propane tanks, thank you!

would you be so kind as to post a link or screenshot?

julie

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Royjohn…I have about every regulator there is. Other than the unregulated one made for it, none of them will screw directly into a 1 lb camp stove cylinder. Is there an adapter that I am missing and why would I bother?..Rob

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Rob and Julie,
Rob, read my post again for why you would bother as far as function. There are lots of regulators with gages, so the price is a lot lower than for the Preset Regulator. I was coming from an acetylene torch, so I used the acetylene regulator (same as for propane, they are interchangeable) I had. I liked the idea of knowing the pressure coming out, to help in setting the gas up for the various tips. Mine has the inlet from the rear of the regulator, like this one on Amazon:

https://www.amazon.com/S%C3%9CA-Propane-Regulator-Welding-Connector/dp/B071WTXL17/ref=sr_1_6?crid=1M76Q4BLZ16ZD&keywords=propane%2Bwelding%2Bgas%2Bregulator&qid=1700012179&sprefix=propane%2Bwelding%2Bgas%2Bregulator%2Caps%2C121&sr=8-6&th=1

Julie, if you click on the illustrations, they will give you the dimensions for the outlet and inlet threads. The outlet threads (male) fit the SLT hose threads (female) directly (type B-B 9/16"-18). The inlet is a different matter. It is a male thread with a globe on the end, 0.880" or 7/8". You will want a brass fitting that mates to the 1 lb tank and has a valve on it, because when you screw the fitting into the tank, the gas flows and you have to shut it off. You will need an adapter to mate that brass fitting with valve to the inlet in the back of the regulator. There are various styles and unfortunately I can’t quite figure out what I have at the moment…it appears to be metric threads, male on both ends…I’m not able to do any more work on this right now, but I’ll come back tomorrow or Friday with the info, if possible. Deep into cutting some stones that have to be done by tomorrow and also preparing to leave town for Thanksgiving. You may be better off with a regulator with a female nut on it like I have rather than the link I gave above.

Just remember that you can price shop for these regulators and buy them for $25 or insist on something more expensive. Also, I did a search for the adapters, which are merely pieces of brass with two threads machined on them and the prices can be as high as $35, but McMaster Carr has them for around $10 and under…since they don’t have any rubber diaphragms like the regulator, I think you can shop for the cheapest ones. You know that if I bought this setup, it was cheap, because I am a notorious skinflint. Sorry not to be more specific, but I’ll try to trace this down by Friday. If you have any background in machine work and thread specs, it is easy to figure this out. The brass-on-brass seats well, so there is no danger of leaks and you can always check your connections with some soapy water and a brush… -royjohn

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hi Royjohn,

No rush! Have fun cutting stones and enjoy your Thanksgiving trip!

I would love a gauge on my propane tank, but based on your instructions it may be beyond my brain power! haha! now, if I were truly my fathers daughter and understood all this, it would be simple. haha!

I was hoping for a “one and done” type of unit!

I think I will stick with my preset regulator…it has worked well so far…

Julie

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Julie,
Beyond your brain power? I think you’re selling yourself short.
It’s just mating threads on a tank valve and regulator inlet by using an adapter. I’m going to persist in looking for the right adapter, because there are lots of folks out there with Meco, SLT and Hoke torches…and probably some others…who would benefit from a low-cost, better option than those preset regulators. Mine works fine, I just don’t remember where I got it…stay tuned! -royjohn

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Royjohn…I just need a torch to do what I want it to do. I have never felt that I needed to know the pressure at the gauge on my current setup. The torch quickly tells me when the tank is empty. When I ran acetylene or propane and O2 from big tanks, that was a different story and I used my pressure gauges a lot to get the flame that I needed. I have always known that the acetylene and propane regulators were basically the same, but I could never find a way to adapt them so that I could swap back and forth. My local welding shop didn’t have the adapters that I needed and just wanted to sell me two different regulators. I used to have one of each, but the propane regulator has come up missing. I would like a little more pressure (flow) from my propane and O2 setup once in a while for casting bigger silver and gold ingots or melting brass, but I will stay with what I have because it keeps big cylinders out of my shop. I have looked into installing a G-Tec and going to NG. The O2 concentrator will likely limit the flame since NG isn’t as hot as propane. I would like to hear thoughts on this from anyone who runs a G-Tec and an O2 concentrator. Thanks for all you information and good ideas…Rob

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contributing factors may have more impact on the efficiency of melting than does the gross BTU/hour output of your torch…I;ve always used shop sized oxyacetylene and oxygen tanks with regulators for same to do melting… the heat output is a lot more and far in excess to get the job done quickly…

just as an aside… 10,000 BTU’s is equivalent to 2.9 kilowatt-hours…10K BTU per hour would counsume 2.9 kilowatt-hours per hour, and that’s a lot of energy… melting takes only a few minutes…6,000 to 10K BTU’s per hour heat energy output is a lot of energy…So far as fuel gases are concerned, natural gas has the lowest heat content per molecule, propane and butane are much higher, as the have more carbon atoms per molecule,… acetylene actually has less heat content per molecule than propane, but burns much hotter because it has a higher carbon content per molecule than any of the other gases, with a triple bond between the two carbon atoms which is highly unstable and energetic… the only other molecule that has the equivalent carbon to hydrogen ratio as acetylene does is benzene which can’t be used as a fuel…it’s liquid and carcinogenic.

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Hi Rob,

regarding “more pressure” on 1 lb disposable propane cannisters while melting…

someone once told me to keep a dedicated tank just for melting, and to only use it until the tank is half full…

so i weight them at the start of use…
the net weight of the cannister is 1 lb (of gas)
weight of gas and cannister alone (say about 2lbs)…
and then weight of cannister connected to regulator/ arrester valve/ hoses weight (say about 2lb 8 oz)

and then i dedicate that tank for melting until i use up half the gas (say 8 oz)

i weigh the tank before melting use, and stop when it weighs about 2 lbs all connected
or 1 lb 8 oz for just the canisters

i then use these half full canisters for my torch, when those tanks need replacing

that way, i am not using a cannister with low volume/ low pressure…for melting

julie

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Hi Royjohn,

haha!

i did run across a term while researching torches, connectors, etc… CGA…for example CGA 600…i did not quite understand what it meant but it sounded like you needed to stay with/ match the CGA that the equipment was designated for…

perhaps someone can elaborate…

julie

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That makes sense. Casting will boil off a lot of propane liquid quickly and you could reach a point where the boiling off can’t keep up with the flame. That is why I like the shorter, larger diameter, tanks better than the tall thin ones. You have more liquid surface area to boil off gas in the shorter one. Theoretically, the pressure should remain the same until all the liquid has boiled off. I doubt that is true in real practice. Thanks for all the good information that you post…Rob

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Hi,

sorry, here are the active links

https://www.airgas.com/resources/cleanpeaks/2017/winter/cylinder-connections

julie

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Hi Julie,
Thanks for the info on CGA, which is similar to what I was reading last night. IDK who this was for…when I put together what I have now, I looked at the materials, the pressures, etc. In general, as the CGA Standards state, you don’t mix equipment designed for different classes of gasses and I would not do that. If you look at the fittings that McMaster Carr sells, they tell you which gas or gases are permitted to use with each CGA #XXX type of fitting. For those for whom this is a new area, I’d suggest that they get some help from a local welding supply that is knowledgeable and possibly also check with the local fire marshal and have them look at your setup. I might also advise that you talk to your insurance agent and document that you discussed your equipment with them and also take pictures of the equipment and keep them in a safe place different from your work area, in case of a fire. So perhaps at a reliable relative’s house or in a safe deposit box. And send the photos to your insurance agent, too. Advise the local fire department of the location and type of your flammables in your home and your home workshop in case they have to enter during a fire. Make sure your smoke and CO detectors are functioning and have alkaline batteries in them. And also be aware of the torque needed for tightening your SLT fittings, so that they are not too tight or too loose. If you use a torque wrench, you’ll need an open-end wrench type claw attached to the 3/8" fitting on your torque wrench to get it to work on the SLT B-B 9/16-18 female nuts. Those are the ones you are using on your preset regulator where it connects to the torch hoses.

Also be aware that the SLT hoses are a plastic (polyurethane) underneath those green and red weave nylon covers. The hoses can become brittle and leak and you can’t see it under the nylon covers…as I found out the hard way when I had a SLT. The shelf life of the polyurethane is reported as 5 to 10 years, but depends on environmental factors where it is used or stored. I’d advise you check to see how flexible your hoses are, which is all you can do unless you do a soapy water leak test on the whole hose. If you had a regulator with a gauge, it would show a leak in the tubing by a decreasing pressure when the regulator is on and registering a selected pressure and the valve at the torch is off. Of course, with propane, you would probably smell the leak anyway. -royjohn

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