Hi Steamchick,H ChrisV: I have a few notions on fuel: Very simply, the hydrocarbon content doesn't define the temperature of the flame: The amount of oxygen (air) mixed with the gas does affect it greatly. I thought Paraffin was cooler than petrol - because my paraffin blow-lamps would not braze, whereas my petrol blow-lamp would. But recently, I rebuilt a paraffin blow-lamp and the flame was MUCH better - as good as the Petrol one.
Butane carries more carbon in its molecules than Propane, so more (denser) fuel. But as the pressure is lower, needs a different matching of sizes to get enough air into the flame for fast (= HOT) combustion. The last few weeks have been too cold (below 10C) in my garage for canister butane blow-lamps to be hot enough on small jobs! - The "reduced pressure" causes the flames to be bigger, more "wooly" and just don't give the focussed heat I need. Propane doesn't worry about temperature above -30C, so is much better in "cooler" climates. The 30% mix canisters you are using will loose most of the propane initially, so the pressure will still drop as the the cannister empties. But initially there won't be the problem I have been having with low-pressure butane canisters in the cold. I only use canister fuel for jobs that will go in a "closed fist" - as the "power" (not temperature) of these blow-lamps is too small for silver soldering anything bigger. Last week I soldered aluminium on the end of a small length of 1 inch channel - but this week I can't solder aluminium on a 5 inch can I am making. The blow-lamp isn't big enough. But I know it is OK when the weather is hotter in summer! (aluminium solder is at about 100 degrees below aluminium melting point. Not the 700 degrees you need for silver solder!).
Propane blow-lamps - because more pressure is available - use smaller jet sizes than Butane blow-lamps - and utilise the higher pressure to get higher velocity gas from the jet - which in turn sucks in MORE air and leads to faster combustion and a hotter, more focussed flame - Ideal for silver soldering. Attached some pics (mock-ups) of some set-ups I use to best apply heat for silver soldering boilers. (I had a problem that the cup-washer on the paraffin blow-lamp fell apart before I got full pressure on this lamp for the demo! - Only 40+ years old! These things are "servicable" items though! - I'll have to cut some leather from a welders gauntlet to make another cup-washer).
Using a horizontal tray of sand and fire-brick, using a vertical tin of sand and fire brick. You can see the 2 types of blow-lamp I use (not hand-held) for pre-heating and that gives me space in the middle for the Propane blow-lamp - using a regulator at 20psi (more and the flame blows-out!). Note the readily available fire extinguisher (To extinguish me if I catch fire!) and the use of extra fire-bricks to enclose the hot job and slow the cooling after soldering.. Both the petrol and paraffin blowlamp will normally get the sides of the boiler a dull red colour, while the Propane blow-lamp applied to the appropriate zone between will get a patch of boiler a decent red to melt silver solder easily. It can't do that without the insulation and 2 extra pre-heating lamps providing more heat. But my left hand cooks inside the leather gauntlet holding the propane blow-lamp! - from the radiant heat from the exposed hot-end of the job. I wear a welder's apron so I don't cook as well!
Watch out that the exhaust from one blow-lamp does not get near the air intake for another blow-lamp, as the flame of that one will be extinguished - with gas going everywhere until it ignites with a WHOOSH! - and sets your clothes on fire. It hasn't happened to me - yet - but I keep the extinguisher handy in case...(!?)
Hope this helps?
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Hi Chris,Update, for Cousins you need to add VAT so works out £5 more.
There is a Sievert Promatic 3366 handle with Pizza ignition, possibly great, just costs more £££ !
Hi Chris,Wow thank you all for so much help...my brain hurts! (-:
Steamchick, some great points there, some I am familiar with but just didn't understand why, now I do and can refer back to this, so thank you. I do have a fire extinguisher for just in case!
Nealeb thank you, that confirms the pilot varies so not as useful as I thought.
TerryD sorry your tea got cold (-: I thank you very much this is all invaluable advice. I will check prices at Cousins.
Its all looking like I should be going for the Sievert kit (without the pilot) for the silver soldering and good to hear someone else uses flogas, and I take on board about the taller cylinder.
One issue for me still to tackle in my mind. Two other uses/jobs I have in mind for this.
Firstly annealing, I sometimes have to anneal 1.5mm sheet brass pieces around 10" x 7". Using my two GoGas cans of butane/propane one in each hand and a base and back screen of Thermalite bricks I struggle to do a decent job, ie thoroughly soften it. I'm gathering the Sievert would cope with this on its own, with a bigger burner, if so what sort of size would be appropriate?
Secondly I have on occasion to forge 1/4" round brass bars, and I have this job upcoming. About a dozen of them which will require several reheatings each.
Currently it would be a DIY can in each hand, once hot enough put these down still burning on their stands on the bench and start hammering on my small anvil, wasting gas of course but lighting them up again each time dosent work out.
That's where the pilot torch handle appealed but since i'd likely have to adjust the flame down i'm not sure i'd gain much. I did look initially at the Bullfinch torches and they have the instant Pizza ignition, but generally they don't look like they have the build quality of the Sieverts, and most kind folks are pointing me towards the Sieverts.
Does this info change the recommendations?
Hi Steamchick,Terry, the blow-lamp you like is a Sievert 0.5 petrol model I bought mid-1970s. Primus and Optimus paraffin blowlamps are very common and cheap. But the Swedish are masters of petrol blow-lamps, providing you use unleaded pertrol. Until the 1990s I was always making new wicks and de-leading the white compound from my petrol lamps and stoves. The advantage being that when camping, the fuel (petrol) was carried in my motorbike tank and easily withdrawn using a hose on a fuel tap, instead of the hose to the carburettor. Old petrol blow-lamps sometimes become available second hand, usually because they need dismantling and de-leading, and new wicks and leather cup washers. Otherwise they truly last a lifetime! And give quick light-up using a Butane blow-lamp to pre-heat, and the best flame of all.
Really my favourite hand-blow-lamp.
On cup washers, the washers I have made only last 5 years or so, but bought ones are pre-shaped and don't fail after more than 20 years. So I buy if I can find a good supplier of the correct part. It means I can use a blow-lamp after it has sat in the cupboard for a year or 2 and not have to make a new washer half-way through a hot job. Also, it means I don't have washer sized holes in my gauntlets!
Hi Jack,I use a MAPP gas torch like this one for most silver soldering jobs: MAPP torch
I break out the oxy-acetylene for heavy materials that require a lot of heat.
I use this solder: stay-silv 56% silver solder
It's expensive, so you don't want sloppy joints. But it flows like water, so you don't NEED sloppy joints.
I use this flux: stay-silv black flux
Hi Murph,Years ago, I decided to be done with second-rate wanna-be torches, went with air/acetylene swirlfire torch heads, and never looked back. No sodding about with preheat torches, firebrick and the like, just light the torch and get 'er done.
Now, for those of you in the UK still buggering about with paraffin and white gas (panel wipe) blowlamps or torches, you can get replacement jets, pump leathers and the like here: https://fettlebox.co.uk/vintage-stoves-lamps-blowlamps.html
I guess not Terry. I just assumed it was MAPP because it was a yellow cylinder. I didn't realise MAPP had been phased out. The cylinder I have is >95% Propylene and labelled as "MAPP Replacement". Burn temp is quoted at 1982 degrees C. Apparently the old MAPP burned in air at 2020 degrees C.Are you still able to get true MAPP in Australia?