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Brazing torch

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Stephen Follows11/05/2019 14:50:25
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Anyone know if I can get a brazing torch kit that will run off a patio gas bottle? Still propane but a different fitting. I want to avoid buying a separate bottle because I use large patio type bottles for other functions.

JasonB11/05/2019 15:08:17
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It's not the torch you need to be looking at but the regulator. Don't think I have seen a high pressure one for the patiogas fitting.

Clive Foster11/05/2019 15:14:12
1948 forum posts
70 photos

I think we went round a similar question 4 or 5 years ago and concluded that you needed an adapter (+ hose?) to go between the patio gas bottle and standard torch regulator. Seems to me that the standard kit hoses are a bit on the short side for hooking up to a big bottle.

I imagine there ought to be an auto-shut off device somewhere in the line, or even at both ends, just in case things go seriously wrong like the hose being cut or a connector coming loose.

Various adapters listed by these folk, Leisureshop Direct, **LINK** which may or may not be directly useful but the link does give some idea of whats out there.

Clive

CuP Alloys 112/05/2019 10:39:23
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213 forum posts

Hi Stephen

Patioheaters and similar devices eg camping stoves and barbecues operate at 37mbar.

Brazing torches operate at 2 - 4bar. That's a ratio of 500 - 1000. That's an interesting engineering project to create a universal system

It's cheaper, quicker,safer to get a propane cylinder with the correct regulator. Then buy a Sievert torch. Buy it from the right source and you will get all the technical help imaginable to ensure that all your brazing projects are successful.

Regards

Keith

duncan webster12/05/2019 14:33:31
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In similar vein I recently got a bunsen burner, the idea being that I could use it for little jobs like boiler fittings and save having to get the propane bottle out. Useless! Does anyone know of a burner that will work off mains gas and generate enough heat to silver solder boiler fittings etc. I'm not talking Flamefast size,

IanT12/05/2019 15:49:59
1386 forum posts
137 photos

I think Clive might be referring to a query I had a good while ago.

I'd purchased a Bullfinch Autotorch 404 for small SIFbronze (e.g. brass) brazing work. I already had a large patio gas cylinder, which I had (wrongly) assumed I could also use for the Bullfinch but it turned out that wasn't possible (different connector).

So I ended up buying a new Propane (Red) cylinder which wasn't that much more than just the cost of a refill IIRC (and very cheap compared to disposable gas bottles). I was then able to attach the Bullfinch directly using the Bullfinch supplied regulator. It all works very well for small SIF brazing jobs as well as any larger silver brazing I need to do.

Regards,

IanT

 

PS The 404 generates higher temperatures than most propane guns are capable of and (in my view) is a viable alternative to Oxy-A for smaller brass brazing work - although obviously it's not quite as versatile. But then it isn't as costly or (potentially) as dangerous either...

Side Frame Assembly

 

Edited By IanT on 12/05/2019 15:59:22

not done it yet12/05/2019 16:07:08
3791 forum posts
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Posted by duncan webster on 12/05/2019 14:33:31:

In similar vein I recently got a bunsen burner, the idea being that I could use it for little jobs like boiler fittings and save having to get the propane bottle out. Useless! Does anyone know of a burner that will work off mains gas and generate enough heat to silver solder boiler fittings etc. I'm not talking Flamefast size,

Natural gas, mainly methane, will have less combustion energy than alkanes with more carbon atoms (carbon to carbon dioxide gives out more energy than hydrogen to water). The only way you will get a hot enough flame would be to swap combustion air for oxygen. I can braze small items with my external mix lampwork burner with propane and the 5 l/minute oxycon. It really needs a 10l/min oxcon as the purity, when flat out, is down to only about 88%.

JasonB12/05/2019 16:23:20
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Duncan, look at some of the jewelers torches. However like the bigger Flamefast torches they use forced air to get the flame hot enough not just what they can suck in.

Assume your supply will be Gas safe etc

Edited By JasonB on 12/05/2019 16:24:47

Andy_C04/09/2019 19:14:55
18 forum posts
5 photos

Sorry for restarting this thread but am considering a sievert propane torch for silver soldering. Does anyone have any comments on the 3486 or 3488 where the 3488 is the more expensive torch with a trigger and pilot flame.

JA04/09/2019 19:29:41
831 forum posts
48 photos

Andy

I have used both and would recommend the 3488. It is far more convenient.

One comment: When fixing the supply tube to the torch, either torch, use spanners on both nuts. If you hold the torch and just use a spanner on the tube nut you are likely to twist the pipe inside the torch. Eventually it will fracture leading to propane leaking into the body of the torch. Fortunately I was not burnt when the inevitable happened.

JA

3404604/09/2019 19:30:50
913 forum posts
6 photos

I started with a 3486 and replaced it with the 3488. The trigger for extra heat suits me better,

Bill.

Thor05/09/2019 05:45:32
1150 forum posts
32 photos

Hi Stephen,

I'm using a Sievert Promatic system with a clip on 0 - 2 bar regulator on ordinary propane bottles that I can get at my local garage. It has worked very well for my brazing work.

Thor

Andy_C05/09/2019 20:02:18
18 forum posts
5 photos

Very many thanks for your replies - most appreciated.

Bill Phinn07/09/2019 16:11:10
230 forum posts
43 photos
Posted by CuP Alloys 1 on 12/05/2019 10:39:23:

Brazing torches operate at 2 - 4bar.

Keith

If this is so, would Keith, or someone, be good enough to clarify for me why the recommended pressures given in this link for oxy-propane brazing are so much lower than this? Is it that air-fed propane torches (which perhaps Keith was focused on) need much higher pressure than oxy-propane torches?

For the record, I have this torch, and the pressure recommended by the retailer for brazing with the general brazing tips (the "multijet" nozzles) is 0.25 bar regardless of nozzle size. Only the so-called "superheating" nozzles (which only fit the larger torch I have, not the smaller brazing torches sold by the same retailer) are stated as needing pressures of 2 bar and beyond.

For general oxy-propane brazing work with this torch I use a Harris twin-gauge propane regulator (which indicates outflow pressure) and have been following the Welders Warehouse recommended pressures for the multijet nozzles up till now. Is it wrong to do so? Should the pressure be higher than the recommended 0.25 bar? Or are the pressures the WW recommend correct because Keith was talking about air-fed propane torches only when he said that brazing torches operate at 2-4 bar?

Baz07/09/2019 17:25:42
294 forum posts

Bill, I use oxy propane with a very similar torch and I usually use about 5 psi propane and between 3 - 8 psi oxygen.

old mart10/09/2019 22:54:19
981 forum posts
106 photos

I bought one of these to utilise the large propane cylinders, it comes with the left hand threaded bottle connector. Later, I got one of the American style "ACME" bottle connectors which fit the propane bottles fitted to fork lift trucks. It is not really hot enough for largescale brazing, but is useful for general heating and is much cheaper to run than my MAPP torch.

**LINK**

For smaller scale silver soldering and brazing, I can recommend one of the MAPP gas torches.

Edited By old mart on 10/09/2019 22:57:28

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