Mini Oxy / Propane sets?

[brozier]

All,

I'm looking at the tools I'll need to make a 3.5" and 5" Gauge Boiler this year. I have a propane torch set with burners up to 50mm which I think should be okay for the exterior of the boiler.

I'm trying to find something for working on the inside of the firebox.

I've looked at Cyclone burners and the hottest I can buy would be about 10kW which doesn't sound very powerful so I'm assuming I'd need to add a second burner to provide general heating on the outside.

If this is so I'd have to buy a second propane setup which by the time you've factored in a second bottle is nudging the price I'd pay for a one of these mini Oxy / Propane (or Mapp or Acetylene) sets.

I'm talking about the ones which use disposable bottles rather than the BOC portapack. e.g.
www.cupalloys.com/products.php?productId=87#

Has anyone used these and any ideas on how long the gas bottles last. E.g. would a pair of bottles be enough for a boiler? From what I can see the Oxygen is used up at twice the rate of the fuel.

Anyone used these before? Any gotchas advice?

Cheers
Bryan

[ron]

Hi Bryan
I've got the set from Proops, the 555C[http://www.proopsbrothers.com/acatalog/Online_Catalogue_Brazing___SilverSoldering_28.html] which looks something similar but a bit cheaper, it does the job but the oxygen bottles don't last very long.
When I was restoring cars years ago I used to have a similar one from Bernzomatic till they stopped selling the oxygen, same criticism of it.
Ron

[mutley]

I made a Simplex boiler using the two largest sizes of Cyclone burner with no problems. Spend some of your money buying heat resistant blocks to build up around the outside of the boiler to keep the heat in. You will be supprised at how small a burner you need if your not trying to heat the workshop at the same time.

Andy

[Julia]

For years I resisted using oxy-propane believing that cyclone burners offered an equal alternative but I tried and failed to make a leak free boiler. I used a big burner for background and the cyclone where I was working - had no trouble melting the silver solder but the area of melt was large.

Eventually persuaded to try the club's oxy-propane what a revelation. The difference is controllability. Using background heat to bring the job up to near temperature but not hot enough to use up the flux then using the much hotter oxy-propane a small area can be brought up to the correct temperature and done. As I could pick how big an area was at melting temperature I could adjust things so I could work at my pace. Some of my heats were quite protracted (I am a novice) but when I got to the last bit the flux (easy flow) was still fresh as it had not been burnt away. Another advantage is that as less of the seam melts at once it is possible avoid using as much high melting point silver solder. (another advantage of the clubs oxy-propane it came with expert assistance)

Now having used oxy-propane I would not dream of going back to my cyclone burners.

[Chris Kelland]

Hi All,

Just like to point out that if you use a variable regulator the 10.3 Kw cyclone burner will run up to 20 Kw. the lower rating is with the standard regulator. Info from the Sievert tech manual.

Use plenty of packing around the job to keep the heat in and direct it. Thermalite building blocks are very good for that, free from your local skip.


Regards,


Chris

[brozier]

Thanks for all the responses. Still not been convinced either way....

Ron how long does the oxygen bottles last on that set? 10Mins 30mins and hour?
I was considering the Proops one as it is the cheapest I could find (and they are local). Does it take the Oxygen bottles from other sets?

Julia do you know what make oxy/propane kit your club has? Does it use the small disposable bottles? Or the BOC rented ones?

Chris I didn't know you could crank up the heat on the cyclone burners I have got a variable regulator so that is an option. Did you still need a second torch for background heating?

Luckily I have a big stock of thermalite blocks from building an extension last year.
I have some fire bricks too (from an open fire place) does anyone know if they are any good?

Cheers.
Bryan

[Noddy]

Hi Brian,
your thermalite blocks will probably spit bits at you as they heat up, some of the fire type bricks are much safer in that regard.

The thermalite could still be used behind a layer of heat resistant material, where it will be protected from rapid or intense heating.

As well as your existing fire bricks, the old pale yellow coloured bricks used in many coalfield and industrial areas were reject fire bricks.

So long as they've received a good slow bake at over 100c (over night would probably do) to drive off any moisture they've absorbed, they should be much more resistant to spalling and spitting than thermalite.

Keith

[circlip]

Nother source for "firebricks" is dead gas fires. The radiants are ideal. In the good ole days, you could quite effectively manufacture a boiler using only a plumbers type blowlamp, no NOT a gas one. I suppose you'd have to nick them from the local "Theme"pub nowadays. Oxy-propane? Someones going to be asking how to use Thermite next. Regards Ian.

[mutley]

Try old storage heaters for fire bricks.
When choosing a torch its not necessarily what you use, its having the skills to get the best from the equipment you do have that will have the greater effect.
As an example I have a friend who builds beautiful models using nothing more than an old pre war lathe and a Warco minor milling machine.
You can have all the fancy heating equipment you want but if you havent got the skill to use it theres little point owning it and lets not forget the early model engineers had little more than a 2 pint parafin blow lamp to build boilers with.

Andy



Andy

[Noddy]

May 8, 2008 13:25:28 GMT @circlip said:

Someones going to be asking how to use Thermite next.

Strangely enough...

Mg alloy car wheels and copper oxide should go with a bang...

Keith

[alanstepney]

you could quite effectively manufacture a boiler using only a plumbers type blowlamp, .... I suppose you'd have to nick them from the local "Theme"pub nowadays.

Well, no, you could ask me.
I still have several blowlamps, both petrol and parrafin, with which I built my early boilers.

Although I now use propane, the old ones still get pressed into service if or when I need additiona background heat.

[alanstepney]

May 8, 2008 13:49:27 GMT Noddy said:

Mg alloy car wheels and copper oxide should go with a bang...

Keith

I dont know about that combination, but I did once have a car catch fire, and when the magnesium alloy wheels caught fire, it certainly got exciting!
(Got the fire brigade a little excited too! lol)

[Chris Kelland]

Hi All,

Thermalite blocks are quite safe, they wont spit at you due to the way they are made, this only applies to Thermalite don't try other makes as they don't work as well. I cut mine to shape with an ordinary hand saw. Old storage heater bricks won't work either as they do just that, soak up loads of heat and cool the job down.

Regards,

Chris.

[mutley]

Hi Chris
Storage heater bricks do soak up heat, however once there hot .....! Warm the job and the bricks slowly, dont rush it and your unlikley get a problem. Boiler making isnt something that should be rushed.

Andy

[ron]

I've found old storage heater bricks excellent, I also used to have a couple of proper industrial boiler insulation bricks and they behaved very similar to storage heater ones.

Brian
I don't really know how long the oxygen lasted but you're talking more like 10/15 minutes or so rather than hours plus one of the bottles I had leaked most of the oxygen away due to the NR valve leaking . I think you really need to look on these kits as handy for extra heat for small jobs but not really for serious boilermaking other than as a one off. If you could find away of connecting them to a larger oxygen bottle they would be a lot better.
They were brilliant for spot brazing the doorskins on old cars as the heat was very local and didn't burn a lot of the electro primer off the new doorskin.
Ron

[Julia]

Bryan
The club has an industrial size bottle rented from a large gas supplier. I am surprised how many of my clubs members have a similar bottle at home. Perhaps its because having tried oxy-propane there is no going back.

[brozier]

Hmm sounds like the mini-sets are not a great idea. 10minutes isn't long when you are a novice.

Think I'll try a Cyclone and see how I get on with it. I could always use my paraffin torch for background heat!

In the good old days you could make a boiler with a paraffin blowtorch. You don't need much heat to soft solder caulk a riveted boiler. But seriously you could get away with a lot more then and I would like to Silver Solder my firebox stays I doubt that would be possible even with skillful use of a paraffin lamp!

Thanks for all the comments I sure you have prevented me from making an expensive mistake.

BTW Julia do you have an article on boilermaking in Model Engineer this week? It was pretty interesting and timely for me ;D

Cheers
Bryan

[Julia]

Bryan
Yes it is my article. Only just got sight of it as I don't subscribe. They seem to have cut off the account at a cliff hanger.

I estimate my oxy-propane burn time was about an hour for the whole boiler so if the little bottles are only 1/4 hour I can see it being expensive.

Julia