Silver soldering torch

[clivejParticipant @clivej]

Any recommendations on gas torches (butane) for anything the size of a model boiler?

Having professionally silver soldered refrigeration in the past I always used a Mapp gas can but obviously this won’t be large enough for a boiler!

Thanks

[Dave HalfordParticipant @davehalford22513]

You need propane and a fat bottle to start with.

[JasonBModerator @jasonb]

Propane is the way to go. 7KG bottle

High Pressure regulator at least to 2bar preferably 4 bar

Sievert torch and a burner around the 7kw mark will cover most things but a bigger burner if the boiler is over say 4″ dia.

[Andrew TinsleyParticipant @andrewtinsley63637]

It all depends on what size of boiler you are considering making I have a large range of torches which range from 40kW, down to mini torches for jewellery.

For a large narrow gauge boiler in 7 1/4″ gauge I have used two 40kW propane torches and an oxy acetylene torch. I don’t expect you will need that amount of heat, but it critically depends on the boiler size and what you may have in the way of a hearth and what insulating blanket you may have.

You will find that it is much better to oversize your torch. You can always turn down the heat if necessary. Almost everyone underestimates how much heat is required and this is the usual reason for silver soldering failures.

Dave is quite correct, for the larger torches you will need a large bottle of propane. I normally use the 49 kg size. I would not go below 19kg for a medium size boiler. The rapid evaporation cools the bottles  and restricts the gas flow.

Andrew.

 

 

 

 

[Bill PhinnParticipant @billphinn90025]

Whatever torch and burner you opt for, you will maximise the heat it can put into the job if, unlike 99% of people demonstrating brazing on Youtube, you insulate the work area. Suitable materials for this include ceramic wool and vermiculite or charcoal blocks.

[old martParticipant @oldmart]

I bought some firebricks to make a small hearth at the museum, about 18″ wide, 12″ high with a sort of top and open front. The bricks are easy to drill with an old masonery drill and my effort simply has an mdf base. It certainly helps to keep heat in. We needed to do something to a long rod and managed to drill 1″ holes in either side with a hole saw.

[BazyleParticipant @bazyle]

As mentioned above get a Sievert torch then you can get multiple nozzles as over time you will want different sizes.
Butane cylinders could freeze up if you use the gas fast in theory but in practice Sievert won’t sell you a butane adaptor anyway. If you do find a butane compatible torch use it as added heat for a big job, not the main source.

Firebricks – note the heavy kiln bricks are not suitable as they soak up the heat. The ones you want are the lightweight and expensive ones, plus some compressed vermiculite boards for filling and small jobs.

[clivejParticipant @clivej]

Thanks for all the replies, as to size of job it won’t be particularly large, say a 2 1/2 in boiler plus all the firebox construction so making a small hearth should be straightforward too

[David George 1Participant @davidgeorge1]

Hi contact Cup Alloys for supplies and information. They will tell you what torch you need for boiler size and which nozzles you need as well as any flux and solder.  They are very helpful.    01623 707 955  [email protected]

David

[David George 1]

On David George 1 Said:

Hi contact Cup Alloys for supplies and information. They will tell you what torch you need for boiler size and which nozzles you need as well as any flux and solder.  They are very helpful.    01623 707 955  [email protected]

David

Another vote for CUP.  Very helpful, and you can get all you need in one go.

[Dave HalfordParticipant @davehalford22513]

As to fire bricks you<b> do not want</b> clay pizza oven bricks or old night storage bricks .

You want these  they take a self tapper so you can use the little angle plates for kitchen worktop fixings to make the shape you want.

My comment on the fat bottle came from Bullfinch (not that they said fat) the bigger torches need the larger area to evaporate enough gas fast enough.

[JasonB]

On JasonB Said:

Propane is the way to go. 7KG bottle

High Pressure regulator at least to 2bar preferably 4 bar

Sievert torch and a burner around the 7kw mark will cover most things but a bigger burner if the boiler is over say 4″ dia.

Hi Jason,

I am in the process of ordering a new set of Sievert equipment to replace my aging Clarke and Calor kit. Could you list the nozzles that you use for my benefit, and others, please.

Regards

Gray,

[JasonBModerator @jasonb]

Unfortunately there is not much to list, as I said a burner in the 7kw range will do for most things and that is what I use from small parts that would sit on the end of your finger to steel fabrications upto 300mm and fairly thick 25×25 section.

This is the torch kit I have and it came from Hamilton Gas, the various parts of the kit are listed at the bottom of the page. I do also have a smaller burner and suitable neck tube that gets used for test running flame lickers and hot tube ignition engines and that could also be used for small work but I don’t bother fitting it.

Maybe Andrew can list what he uses in the bigger sizes for larger boilers.

[noel shelleyParticipant @noelshelley55608]

BUTANE ? Why ? It will freeze or if cold not gas off at all. You need PROPANE even this will freeze if demand is to high, pressure will then drop below what you may need, that’s why you need bigger bottles to give evaporative surface area ! 13 or 19 Kg bottles. Whilst everybody talks of Sievert gear do not discount BULLFINCH equipment, you may find it as old stock, I did and got a complete set of torches up to about 2.5″ dia for almost nothing. The fire bricks you need are the type used in pottery kilns, American K23, their very soft and light, fixed with air setting cement. Ceramic fibre is marvellous stuff. A simple sheet steel or angle frame bolted or welded together for a hearth. DO NOT use Nightstor or similar heater bricks they store heat, you want it to reflect the heat. For solders and fluxes CuP alloys will help you get the right materials for your job.  Good luck. Noel.

PS Bullfinch is still trading and has an interesting web site that lists useful information on burners, their power and the size of bottle needed Etc.

[Trevor Drabble 1Participant @trevordrabble1]

I use the excellent brazing hearth kit from Cup Alloys in conjunction with the equally good Sievert Primus 2000 cylinder and it’s 4 nozzles ( 0.25Kw -7Kw) , which I find does the greater majority of my silver soldering  work most satisfactorily.  Also , if I recall correctly the cylinder refill only cost £11.70 from my local dealer.

[Graham MeekParticipant @grahammeek88282]

Thanks Jason,

The kit I was looking at comes with the larger nozzle. I was wondering which nozzle to get for the smaller jobs which I do occasionally. Your suggestion fits the bill.

Regards

Gray,

[Trevor Drabble 1Participant @trevordrabble1]

Graham , for your information , the 8842 burner that Jason’s mentioned is the 0.25Kw one described in my post.

[Trevor Drabble 1]

On Trevor Drabble 1 Said:

Graham , for your information , the 8842 burner that Jason’s mentioned is the 0.25Kw one described in my post.

Just a cautionary note about owning the 8842 and 2941 burners, in case anyone hasn’t quite grasped the implications of Jason’s point about the “suitable neck tube”. These two burners of very different size can’t be used with just the one neck tube; you’ll need two different neck tubes.

If you want your smallest burner to still be the same 0.25kW as the 8842 and don’t want to have to buy two neck tubes, a better bet would be to buy the kit that includes the 2941 burner and 3511 neck tube, and just buy a 3938 burner at the same time; this 0.25kW burner fits the 3511 neck tube just as the 2941 does and you won’t need to bother buying the 3501 neck tube as well in order to run a 0.25kW burner.

I agree with Noel that Bullfinch still has a lot going for it: like him I have all of the Bullfinch burners, as well as all of the Sievert burners except most of those in the “Light Line” range.

I think it’s worth doing a fact sheet about Sievert and Bullfinch torches and burners, as well as ones from the Calor/Weco, Cannon and Lorch brands, because there are some important variations in thread fittings and interchangeability. I am talking about historic torches and burners as well ones still in production. Sievert especially is all over the place when it comes to its thread fittings.

[KEITH BEAUMONTParticipant @keithbeaumont45476]

I have the similar torch to Jason,purchased from CUP,but mine does not have a regulator and I screw it straight onto a 3. 9 Propane tank. but I have often wondered if a regulator would be an improvement. I also have a range of jets. This information regarding needing different neck tubes is new to me. I made a hearth from Vermiculite slabs, about 12 inch cube outside dimention. Originally I fitted a half top cover, but had problems with the flame going out,usually just at the point of the solder flowing! Removing the cover solved this,as I reasoned that it was preventing the nozzle getting sufficient  oxygen.

Keith.

[Clive Brown 1Participant @clivebrown1]

For interest, here is a data sheet for Bullfinch burners. I soldered my 1 1/2″ Allchin boiler with just a 1240 burner. For 5″g loco boilers I added a 1250. In all cases the gas pressure, and hence heat output would be well  above the figures listed. 

I’d point out that neck tubes are neccessary with the larger boilers and burners if only to keep one’s hands and face away from the glowing mass of copper.

[KEITH BEAUMONT]

On KEITH BEAUMONT Said:

I have the similar torch to Jason,purchased from CUP,but mine does not have a regulator and I screw it straight onto a 3. 9 Propane tank.

What’s on the tank end of the hose, Keith? Sounds like it must be something with a 5/8” male POL fitting.

[KEITH BEAUMONTParticipant @keithbeaumont45476]

Bill,  It has the standard brass, taper fit, left hand thread fitting that fits straight onto the tank.

Keith.

[noel shelleyParticipant @noelshelley55608]

Running propane, where my system used 3 X 47Kg bottles, I had pressure  gauges on both the bottles and the reduced pressure, This was vital to avoid the pressure drop that would occur as the liquid level and evaporative area reduced. On a hot day it was not uncommon to see the bottle pressure reach 150PSI so I note with interest Keiths use of a torch with no regulator. I would have to question whether this was originally intended for Butane ? A 19 Kg bottle with less than 30% left after about 15 mins of use would start to loose pressure and need help to maintain the 45psi I needed, the burner had a 1.8mm jet, and this on a pleasant summer day. The Bullfinch data states min bottle size for the larger burners as 47Kg. The bigger the bottle the cheaper the gas is per Kg. I did boil the kettle twice a day for a year on the gas left in a 13Kg Butane bottle due to cold weather and it not being able to gas off !  Noel.

[KEITH BEAUMONTParticipant @keithbeaumont45476]

Since my post above, I have had a look to see exactly what I have. I purchased the kit from CUP at one of the shows, several years ago and it is  listed as Sievert Propane PMPX Kit. No mention of need for regulator. The connection to the tank has a swivel joint and a button to press to allow the gas to flow after opening of the tap on the bottle. My needs are modest and I only get involved with small parts.

Keith.

[Bill PhinnParticipant @billphinn90025]

It sounds very much like what you have there, Keith, is Sievert’s hose failure device, part number 305401. It’s a lot better than no regulator. This is what Sievert themselves had to say about it in an email to me:

“Whilst the HFV are not regulators in the truest sense they give some regulation due to the way they operate. If you wanted to be certain of the pressure and have the safety benefit of an HFV I would recommend using the 306311. This will enable you to adjust the pressure between 1 and 4bar and have the HFV function.

As Hamiltons don’t stock them you can purchase them from Toolbank…,

Best Regards

Phil Brookes

Sales Support and Service Coordinator

SIEVERT UK LTD”

In my book, this effectively means you can use any suitable high pressure propane regulator in line with the HFV. When I’m using my HFV this is what I do, and the regulator I usually use is a Sievert fixed 2 Bar one, because it is something I happened to have spare. Bear in mind that not all HP propane regulators will have suitable couplings for adding in after the HFV, but some certainly do.

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