# C-Type Boiler Conversion



## Steve Shyvers (Jan 2, 2008)

Garrett wanted to see some photos of the c-type boiler conversion I did for my RH Billy. These photos were originally published with an article I did last year for Steam in the Garden. Lots more info in the magazine article.

I'll call the conversion a success because the loco is a very predictable and controllable steamer. It sure taught me a lot about blast pipes. Of course I've got a list of "improvements" in mind which may or may not be. If they are then they will be used for the next alcohol fired loco. 

























- 
Steve


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## xo18thfa (Jan 2, 2008)

Steve: Looks real good. Are you putting any kind of caulk between the firebox and the boiler barrel, or just fitting it real close. 

Bob


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## Spule 4 (Jan 2, 2008)

Thank you, the photos make this very clear. 

We used to get SIG, should probably do it again. Which issue was this conversion in?


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## Steve Shyvers (Jan 2, 2008)

Bob, 

The firebox has small flanges along both sides and the back. The flanges along the sides are pinched against the boiler shell by the boiler wrapper. (The RH boiler wrapper is thick brass.) This is the only mechanical attachment of the firebox to the boiler. There is a piece of ceramic sheet insulation sandwiched between the back firebox flanges and the backhead, and another piece in the butt joint between the front of the firebox and the boiler. 

A long time ago I was told that this type of conversion had been done before to RH locos, and silicone caulk was used to attach the firebox to the boiler. Silicone caulk would be easier to do and mechanically more secure, but I wanted to be able to disassemble it easily to make changes, if necessary. (The firebox is tinplate from old olive oil cans, and was meant to be temporary until I fabricated something better. That was 2 years ago.) 

Steve


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## Steve Shyvers (Jan 2, 2008)

Garrett, 

The article was a 3-part series and appeared in issues 101, 102, and 103. 

Steve


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## xo18thfa (Jan 2, 2008)

Posted By Steve Shyvers on 06 Feb 2010 10:33 AM 
Bob, 

The firebox has small flanges along both sides and the back. The flanges along the sides are pinched against the boiler shell by the boiler wrapper. (The RH boiler wrapper is thick brass.) This is the only mechanical attachment of the firebox to the boiler. There is a piece of ceramic sheet insulation sandwiched between the back firebox flanges and the backhead, and another piece in the butt joint between the front of the firebox and the boiler. 

A long time ago I was told that this type of conversion had been done before to RH locos, and silicone caulk was used to attach the firebox to the boiler. Silicone caulk would be easier to do and mechanically more secure, but I wanted to be able to disassemble it easily to make changes, if necessary. (The firebox is tinplate from old olive oil cans, and was meant to be temporary until I fabricated something better. That was 2 years ago.) 

Steve 



Thanks Steve. I have not tried a Type "C" yet, but want to. I've heard they need an airtight firebox or the don't work. I am like you and want the ability to disassemble, I will go with your method.

Bob


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## xo18thfa (Jan 2, 2008)

It just dawned on me, you could probably retro fit just about any single flue gas fire to an alcohol burning Type "C". Or to a ceramic defused gas burner. Do you think you could do it with a Ruby??


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## aceinspp (Jan 2, 2008)

BTW would the T handle shown with the plastic hose is to be used for a type of hot water bath? Later RJD


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## Steve Shyvers (Jan 2, 2008)

RJD, 

The T-handle thing is the homemade blower valve. The blower nozzle is at the other end of the copper line that snakes from the plastic tubing to the front of the boiler. If doing again I'd silver solder a copper tube through the boiler steam space instead, but at the time I was nervous about any modifications to the boiler it self. 

Ditto with attacing the firebox. Next time I'll silver solder a couple of copper rails to the bottom of the boiler and attach the firebox to those with small screws. 

Steve


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## Steve Shyvers (Jan 2, 2008)

Bob, 

There's not much room under the aft end of a Ruby boiler for the wicks. The boiler is pitched low, and you'd probably have to fit one of the wick tubes between the eccentric rods. Of course you could graft some more boiler length onto the backhead end, but now you're changing the scope of the project. However, it's worth a study and a try. Several years ago I flippantly scoffed at the idea of a coal-fired Ruby. Then look what happened. 

Steve


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## seadawg (Jan 2, 2008)

Looking good Steve! Expand a little, if you would, on what you learned about blast pipes. That is the current issue bouncing around in my head. I found a much bandied about formula that says a good starting orifice diameter is 1/7 of the piston diameter. I also am aware of the 1:3 and 1:6 ratios for the distance to stack (bottom of stack I.D. x 3) and overall stack length (bottom of stack I.D. x 6). 

My problem is the exhaust cross pipe that the original butane fired "blast pipe" screws into has a 3mm thread, so the I.D. of a 3mm threaded copper pipe is smaller than my required orifice. I've got some 3mm stainless but the wall thickness is so small it doesn't want to take a thread. I'm thinking about tapping the cross pipe to a larger size (i.e. 4mm) but then I'm doing stuff that I can't back out of, without remanufacturing a replacement non-standard exhaust ("blast") pipe.


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## aceinspp (Jan 2, 2008)

Thanks for the info Steve. Later RJD


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## Steve Shyvers (Jan 2, 2008)

Dave, 

I made a series of blast pipe nozzles that could be swapped out to experiment with orifice sizes and heights. The nozzles were made from little brass hose barbs designed for use with soft plastic tubing. They were threaded 10-32 and had a 1/4" hex portion for grabbing with a wrench. The barb ID was 3/32", and I pressed in little brass plugs that could be drilled out to different diameters. 

I'd read various sources with recommendations for blast nozzle orifice sizes, and I also peaked in the smokeboxes of a couple of RH coal conversions to see what nozzle sizes were used. The "standard" seemed to be about 1/16" orifice diameter for RH size cylinders. 

When I set up the Billy I didn't really understand how to apply the 1:3 and 1:6 ratios, so starting with a 1/16" diameter orifice I experimented with nozzle heights until I found a height that seemed to work best. Of course I didn't know anything about loco smokebox petticoats, either, so didn't fit one. At a later stage of experimentation I did install a petticoat, sized and adjusted it to the blast nozzle and chimney using the 1:3 and 1:6 rules as best as I understood them, and the steaming perfomance was worse! Out came the petticoat and steaming was better again. 

I've learned since that when using the 1:3 and 1:6 ratios the apex of the cones are not supposed to be positioned at the very top of the blast nozzle. The idea is that the cone sits in the blast nozzle orifice so that the apex is down inside the nozzle. This means that as the orifice is made bigger, the apex of the cone is farther down inside the nozzle, and the nozzle has to be accordingly higher A good design tip is to make a couple of thin metal templates of 1:3 and 1:6 isoceles triangles. Stand these in the blast nozzle to judge the correct heights for the petticoat and chimney tops. 

Right now my Billy has a 0.052" (or is it 0.055"?) blast nozzle orifice. I experimented with sizes from 0.070" and down. Larger sizes would barely make steam fast enough to keep boiler pressure up. The smallest sizes enabled the loco to pull 24 axles and keep the boiler at 50+ psig. I think the small size is necessary to fan the fire enough to make up for various inefficiencies in the whole arrangement. Overall there's not a lot of heated surface, and only two wicks to supply fire. 

Steve


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## seadawg (Jan 2, 2008)

AWESOME POST! Really getting down to the nitty gritty! I'm wondering how small you can go before you have back pressure concerns and also, does there need to be large I.D. piping up until you get to the actuall orifice? 

Where'd you find the hose barbs? Like aquarium accessories and stuff?


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## rbednarik (Jan 2, 2008)

Dave and all, 

For the exhaust nozzle diameter, 1/7 the diameter of the cylinder bore is usually a good place to start. I believe the C-16 has 9/16" cylinders? If this is the case, then the exhaust nozzle should be 0.080" in diameter to provide the optimal amount of draft without causing backpressure. 

As far as the size of the exhaust piping, make the ID of the pipe as big as your exhaust port diameter, and use the exhaust nozzle to reduce the diameter. This gives you free flowing exhaust, while allowing you to restrict it to whatever exhaust velocity you desire. 

A 3mm external threaded exhaust pipe will work fine, you should turn up a cone to fit over the copper pipe and reduce the ID to the exhaust nozzle size. This will also allow you to move the exhaust pipe to center it under the stack without having to modify anything else. You can also turn up different size nozzle cones and experiment with them as well. 


With the 1:3 cone, be sure that you have fashioned a suitable petticoat to help guide the exhaust into the stack and provide a higher velocity venturi effect, giving you better drafting. 

On the C type boilers, so long as the firebox is close fitting to the boiler, and is lined with ceramic insulation on the inside to provide both a heat sink and help seal up any erroneous gaps, it is not necessary to make sure it is 100% airtight and seal it with caulk...after all, there is a fairly large hole on the bottom that is letting in quite a bit of air. 
It is wise to note that fitting an air baffle to the bottom of the wick cups (if space is prohibitive, it can be added on the firebox walls as well) can improve the steaming rate and efficiency of the burner and boiler by reducing the amount of cool air that is drawn in. 

Since you are dealing with only one flue, it may be worthwhile to fit a section of dry cross tubes into the flue to slow down the flue gasses and use them more efficiently before exhausting them up the stack.


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## Steve Shyvers (Jan 2, 2008)

Dave, 

The hose barbs have been in my garage for 20+ years. Surplus junk from a machine I used to work on a long time ago. Not sure where to get them today, but something similar could undoubtedly be found or made from scratch. Ryan has answered the question about the size of the exhaust line up to the nozzle itself. 

Steve


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## Steve Shyvers (Jan 2, 2008)

Ryan, 

Thank you for contributing your insight. Now I'm curious. What do you mean by "dry cross tubes" and how are they fitted into the flue? One of the things I wrestled with for my Billy conversion was getting sufficient thermal contact between the flue wall and the "dry" lengthwise tubes that were installed. (Still a subject for more experimentation based on some very intelligent questions and comments from last summer's NSS in Sacramento.) 

Steve


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## rbednarik (Jan 2, 2008)

Steve, 

Much like your concept,only with a series of rods or tubes mounted in an X (perpendicular to the length of the flue) to a tube that has the OD of the flue and a fairly thin wall. I have seen the dry cross tubes done only on a few engines, but previous experience with wet (water carrying) cross tubes allows for greater efficiency pf the boiler while still retaining the same dimensions...if that makes sense. Often the cross tubes are in a cascading pattern starting at 45* and either escalating in a spiral, or in opposing fashion, going say, 45* and then 135* every other tube, down the length of the flue. 

Tubes going the length of the existing flue will only slow the gasses somewhat (as you said a turbulator), where as tubes mounted perpendicular to the flue length will create bobs and weaves in the heat waves. 

One is not necessarily looking for this to be a heatsink and provide thermal contact, but rather an in-flue baffle or choke that allows the gasses time to finish expanding and possibly burn off some unused alcohol vapor. 

A choke (reducing ring) can also be fitted to the end of the flue or flues to help balance the heating surface vs BTU output of the burner by following the same concept of slowing down the gasses. We did this on the Accucraft GS-4's to help balance the 1/2" flues with the large 3/4" one. 

Most C types have two or more flues that would equal the overall diameter of the C-16 or Billy's single flue, and are therefore a bit more efficient from the get-go, as the flames are heating a larger area of the water. As you found out, it takes a little experimenting to get the single flue to work well, but it is easily done with the single flue and the right burner output.


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## Steve Shyvers (Jan 2, 2008)

Here are some more photos that show the blast pipe arrangement in more detail. The first photo shows how the exhaust lines curve around the standard RH steam supply "tee". Forming those lines was agonizing, and they resisted every effort to make them symmetrical. The second photo shows a view from underneath.

The steam line are slipped into the double-barreled brass ferrule. Friction holds it in position quite well because the two steam lines aren't absolutely parallel or straight.



















The next photos show the blast pipe base slipped over the ferrule, and then the blast nozzle in place. The blast pipe base assembly is designed to attach to the RH smokebox casting, and then the whole smokebox/blastpipe assembly slips down over the ferrule. The blast pipe base is made from a length of brass pipe, and the ferrule is a slip fit inside it. Condensate and oil fill up the 0.002" or so gap between ferrule and pipe, and seals it well enough for steam, but allows some amount of condensate to drain.



















Final photo shows three of my experimental blast nozzles.











Steve


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