1.5" Scale Boiler Manufacturers

[dkellldog]

Regarding Lima Superpower boilers in 1.6 scale, the grate area is huge and getting the correct number and size of tubes in a propane fired boiler is very problematic. In lieu of a combustion chamber, can the grate area be blocked off at the flue sheet end to get the tube ratio to grate area in the 8-12% range? If so, should an arch be put over the blocked off grate area to narrow the gas path as the heat enters the tubes?
Scaling an H8 boiler, 12.25"x 22.25 inches of grate area with scaled tube length, 52" seems pretty problematic. I'd like to hear from the experienced boiler people about how they solved this type of conundrum.

Dkelldog

[Glenn Brooks]

Regarding Lima Superpower boilers in 1.6 scale, the grate area is huge and getting the correct number and size of tubes in a propane fired boiler is very problematic. In lieu of a combustion chamber, can the grate area be blocked off at the flue sheet end to get the tube ratio to grate area in the 8-12% range? If so, should an arch be put over the blocked off grate area to narrow the gas path as the heat enters the tubes?
Scaling an H8 boiler, 12.25"x 22.25 inches of grate area with scaled tube length, 52" seems pretty problematic. I'd like to hear from the experienced boiler people about how they solved this type of conundrum.

Dkelldog

dkell sog,

Iam very interested in what replies you will receive to your question. You might clarify if you are designing a new boiler, or working with an existing boiler. Your comment that the grate area is huge for a Lima boiler suggests you are looking at an historical prototype anthracite coal burner design. anthracite coal burners were noteworthy for having extra large grate area compared to bituminous fired boilers. Propane doesn’t require near the combustion air volume of either anthracite or bituminous coal. So you likely would/could reduce “grate area” in either case. However, I only have experience in coal so not knowledgable enuf about propane design to recommend an ideal configuration….

Nevertheless, looking forward to the interesting solutions to your question!

Glenn

[Soot n' Cinders]

It likely wouldn't be a problem, you would almost never work the engine hard enough to max out the boiler capacity or the power of the cylinders. Duncan Herring built an N&W class A and thats how it behaves. It also has a massive firebox, though I dont remember the exact size off hand, and a bunch of 1in copper flues. It has no problems steaming.

Another thing to consider is the prototype ratios dont always work out well when scaled down. For a given scale, length is scaled linearly (x^1), area is scaled to the square (x^2), and volume is scaled to the cube (x^3). So for 1/8 scale, the length would be 1/8th the prototype, the grate area would be 1/64th, and cylinder volume would be 1/512th.

I would leave the grate area scale but do away with the combustion chamber for simplicity's sake, it'll make construction much easier. Also, I would just go with 1in K copper flues and be done with it.



And Glenn, Dkelldog mentions an H8 which is not an anthracite burner. Lima would overdo the fireboxes on their locomotives so they could produce more steam than the locomotive could consume, this made them free steaming and very forgiving. Im sure anyone who has run SP 4449 or NKP 765 could chime in on how well this works but they kept the trend through the end of steam so must've been alright.

[Bill Shields]

Be careful about what your State regulations are regarding what is called a Model Boiler...especially with respect to grate area.

[Berkman]

a 1.6 scale super power will fire great. The bigger the boiler and grate area the more "free steaming " it will be.

Typically it's the smaller locomotives that are more "picky" about how they are fired. But every large 7.5 gauge locomotive I've run with a wide firebox (4-6-4, 2-8-2, 4-8-4) etc have been VERY easy to fire regardless of fuel.
They have ample steam capacity, and can almost always make more steam than they can use.

Just look at all the LE 4-8-4s and NKP berks running, oil, propane, coal- makes little difference, I think if they are setup correctly with the front end and burner arrangement they will all make huge quantities more steam than can be used.

a LE 4-6-4 , light or "alco", will have nearly if not as big of a firebox as a 1.6 berk. Even the USRA 1.6 mikado, offered by RRSC/Godshall has a large firebox and the several I've run fire great. Maybe only an inch or 2 shorter than a berk.

Now a coal fired 4-8-8-4 or C&O H8 2-6-6-6 might be a little tougher to fire on coal ONLY due to be able to properly see and accurately place coal into the front of such a long fire box, but the large grate would make exceptionally free steaming. The coal issue would be eliminated with oil or propane firing. a 1.6 coal fired H8 would be near the pinnacle of what could be built in 1.6 scale. Imagine one in 1.6 scale to the level of accuracy and detail of the various Krieder Berks.... wow

[NP317]

I have operated a stock (almost) Allen Ten Wheeler burning coal that was a steaming demon! The best boiler efficiency I have experienced.
The front third (approx.) of the grate area was blocked off to decrease air inlet volume.
The exact % blocked off had been carefully calculated based on prototype practice with scaling taken into account, and the results are highly successful.
Keith Sternberg's work, in Washington State.
RussN

[RR Ty]

a 1.6 coal fired H8 would be near the pinnacle of what could be built in 1.6 scale. Imagine one in 1.6 scale to the level of accuracy and detail of the various Krieder Berks.... wow

That’s the goal, just have to find that elusive 25th hour in a day

[RONALD]

Just before he died I had ordered a boiler from Ray Pannel. Here is how it came to me after he died:

http://www.chaski.org/homemachinist/vie ... SA#p276837

Here are two more photos of Ray's work. Sorry to say, I ordered it earlier than I had planed, and it still is on that support.

Will it ever be part of a locomotive, can't say.

[dkellldog]

Regarding my question on the Lima superpower boiler, I did fabricate a 12" ID boiler per the LIMA elevation erection drawing of an H8. Weld quality was good, the proper steel was used and the welders here are AWS certified.
Now the ugly part. I used 1" steel tubes with 1/4" ligaments in the tube sheet. After using a hand reamer, the flue holes reduced the ligament dimension to less than 1/4" on the 1/2" thick flue sheet. Since I had the steel fire tubes already, I expanded those tubes into the boiler shell.
Then the nightmares started. How much more time and money should I invest in a suspect boiler? In a fit of mechanical pique, I cut the boiler in half in front of the firebox, cut out the firebox and smokebox flue sheets ,then put in new flue sheets with a different hole pattern and welded it back together. Argh! I have 1" x 13 gauge steel boiler tubes available with certs, let me know if you need some.
I'd sure like to know how Andy got quantity (58) 3/4" tubes in his H8, as listed in LS magazine.

I'm not burned out on the project, I still enjoy all the challenges.

[Berkman]

wouldn't a 1.6 scale H8 need a 14 inch boiler that tapers down a bit near the smokebox?

[RR Ty]

wouldn't a 1.6 scale H8 need a 14 inch boiler that tapers down a bit near the smokebox?

Yes, a 1.6” scale H8 would hypothetically have a 14” boiler. 1.5” scale would be too small for a 14” boiler. One could build a 12” boiler for 1.6” scale and make up the difference in diameter in the jacket though.

[318J]

I used 1" steel tubes with 1/4" ligaments in the tube sheet. After using a hand reamer, the flue holes reduced the ligament dimension to less than 1/4" on the 1/2" thick flue sheet. Since I had the steel fire tubes already, I expanded those tubes into the boiler shell.
Then the nightmares started.

Curious, what specific issues did you run into resulting from the tubes being spaced thatclose together?