Model steam boilers

There's a guy here in town that needs a coal or wood fired boiler for a
4 foot model boat. I know you can buy them but I think I could make him
one from pipe and common brass fittings. Not sure of all the details
yet. He wants it to be vertical so is there any common container that
could be modified to do this? Maybe some restaurant deal like a coffee
urn or sumsuch.
Reply to
daniel peterman
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Tell him to start thinking more about alcohol or propane. A wood or coal fired boiler will take to much room for a 4' model. Anything small enough to fit will not put out enough steam to run anything other than a small wobbler. Solid fuel is also nasty and hard to get fired up and has 1/3 to /12 the BTUs of the same weight of propane. There is just barely enough room in my 42" tug for a Stuart double 10 and a modified yarrow fired by a chopped down propane tank. Most model boilers are made from copper tube or formed and silver soldered copper sheet. The expensive parts are the model size fittings. Regular brass plumbing fittings are about 20 times to big.
Get the book "Model Boilers and Boiler Making" by N.K. Harris. All the theory and several good plans in the back.
And above all be very careful building the boiler. 5 or 6 oz of water at 320F can pack quite a punch if a seam gives way.
Reply to
Glenn Ashmore
Daniel,
The book mentioned by Glenn is indeed an excellent tome covering the sizing, design, and fabrication of model-sized boilers.
All steam boilers need to be treated with care and understanding. See if you can lay your hands on the recommended book.
What size engine is in the boat? (# of cylinders, bore x stroke, double / single acting, rpm...).
Wolfgang
daniel peterman wrote:
Reply to
wfhabicher
He hasn't made/bought the engine yet. I assume it will be a single cylinder kinda like in those old steam launches he showed me a picture of. I would just make him a pressure vessel and heat it with propane but he wants authenticity. Would something like a pipe bomb work? I mean you cap off some iron pipe with an outlet at one end and a propane torch at the other end. I suppose you would need a regulator valve to let off pressure so it can't blow up but I think the model train guys have solved that issue. I just like thinking about simple safe solutions to these concepts
Reply to
daniel peterman
You definitely need the book. Your heat source is limited so you need the best conductivity you can get. Iron pipe is not it. Copper is far superior. If he is planning an "African Queen" type launch the boiler would be a vertical but anything larger would normally be a horizontal. Small horizontals are also generally easier to fire efficiently.
If he is planning to actually sail the boat he needs to sacrifice a little "authenticity" and use propane. Wood or coal will take forever to build up a head of steam nursing the fire all the time and then he will only get a few minutes of steaming time on a stoking. Plus he will have to disassemble the steam piping and remove the boiler to clean out the ash after every run.
On the rare occasions that I build up the nerve to actually sail my tug I just fill the boiler, oiler and propane tank, fire her up and launch her. I can run for about 30 minutes on a half size torch tank and when I am done just drain the boiler, remove the propane tank, dry everything off and pack her up. That can take some time because once the deck is off I usually have to conduct a short class in steam technology for all the bystanders it attracts. :-)
Reply to
Glenn Ashmore
picture
I don't want to be a wet blanket but his really isn't something you should be doing without a very thorough bit of research. Boiler design is very specialised for two reasons. Firstly safety, and secondly to ensure that they work.
The safety reason was brought home to me the other day when I was having a conversation with a friend and the potential for accidents dawned on me. For the boiler to be giving steam at an acceptable rate and pressure it is probably around half full of water that isn't at boiling point - it's a lot higher - could even be aproaching 200 deg C in some cases. Now, imagine that you have a burst. The steam escapes right and releases the pressure - yes but all that water that was way over boiling point at atmopheric pressure will practically instantly vapourise explosively. Huge amount of stored energy in a small volume of water. Not something to mess with unless you know what you are doing.
To work properly the boiler needs an evaporative area matched to the heat source and the rate at which steam is needed. It needs a safety valve designed to release at just over working pressure and proven to be able to discharge as fast or faster than steam can be produced. It needs a means of knowing the water level so you don't run dry and rapidly over heat.
Materials for boilers need to be put together to form a pressure resisting shape avoiding stress risers. They need to be corrosion resisting. Internal stays are usually used to strengthen the boiler. Certainly anything like a steel pipe with Vee threads cut in it must be avoided as they are horrendous stress risers, will corrode and any normal pressure rating for the pipe is immaterial at the higher temperatures of a steam plant.
AWEM
Reply to
Andrew Mawson
That makes good sense Glenn and I will recomend he take that course.
Reply to
daniel peterman
Good advice Andrew and I will pass it along. You know your stuff obviously and yes< I know this is dangerous to be messing around with. They make those little steam engines that run on some pellets but can't power anything so maybe he is thinking of that method of stoking.
Reply to
daniel peterman
I do not see a message containing the referenc eto the book. Can somebody repost the boiler book title and author.
Thanks
MG
Reply to
MG
============= Sure
------ posting was ---------- Get the book "Model Boilers and Boiler Making" by N.K. Harris. All the theory and several good plans in the back. -------------------------------
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Also see lindsaybks.com they have several steam power books from models to full size locomotives. I buy a lot of their books and have gotten goods service/value.
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Unka' George (George McDuffee) .............................. Only in Britain could it be thought a defect to be "too clever by half." The probability is that too many people are too stupid by three-quarters.
John Major (b. 1943), British Conservative politician, prime minister. Quoted in: Observer (London, 7 July 1991).
Reply to
F. George McDuffee
snip----
How cool! Any chance you could email me a picture, Glenn? If so, I'm on a dial-up, so not too large, please.
TIA
Harold
Reply to
Harold and Susan Vordos
I think he best get educated more. Seriously, asking means he doesn't take magazines that have details or belong to club ....
Many places require government testing of the boiler so they don't blow up...
Boilers are not simple nor baby talk. They kill people from time to time.
Martin
Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.
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daniel peterman wrote:
Reply to
Martin H. Eastburn
According to Martin H. Eastburn :
[ ... ]
Certainly if they are going to be fired up in the proximity of anyone other than the person building them. I think that it is still legal to commit suicide by poor boiler design.
A lot of the requirements for boiler construction include a certifiable traceability of the materials used -- and certification of anyone making welded or silver soldered joints.
Even professionally designed and built ones subject to improper maintenance or operation procedures.
And brass in contact with water -- especially water that hot -- will lose zinc to the water weakening the brass parts and leading to early failure.
And a coffee urn may suffice for boiling water -- but enclosing it to hold the pressure generated so it can be used to drive a steam engine -- no way!
Get all the books you can. And determine what certification requirements exist prior to starting construction. You may need to get it inspected at various stages of the construction -- and if you miss one of them, you will likely have to start over.
Good Luck, DoN.
Reply to
DoN. Nichols
Thanks don. I am gonna steer clear of this project and tell the guy to buy a tested setup
Reply to
daniel peterman
As this is for a boat, I would also recomment getting 'Model Stationary and Marine Steam Engines' by the same author. It has lots of useful information about different types of engine and what size/types of boat etc. as well as lots of construction tips and sample plans.
-Mark
Reply to
Mark Rae
What he said. You can't just braze together some pipe and fittings and expect the boiler to a) work and b) be safe.
Reply to
Jim Stewart
I'm not gonna mess with it. Boilers are bad news in the wrong hands and I don't have the right hands right now.
Reply to
daniel peterman
...phew !
AWEM
Reply to
Andrew Mawson

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