mott
Hi-poster
Posts: 151
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Post by mott on Oct 14, 2005 19:10:22 GMT
Has anyone any experience of converting a 3 1/2 " Rob Roy boiler to gas firing? Where did they get the kit and was it succesful? Mott
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Post by the_viffer on Oct 14, 2005 21:05:12 GMT
Ah a subject dear to my heart.
A very good friend of many on this list a D i c k (I have to use spaces or they turn it into thingy: try it and see) Clements who was an especially good mate of mine planned to do the very same thing. Alas cancer claimed him beofre he got it done. D i c k reckoned that it could be done but that you needed a kin large gas bottle behind the driver. I think he was told by Martin Evans to shorten the distance between the tubeplate but I'm not now certain of that. He went to a good deal of trouble on getting the burner right and as I recall instead of having a blow torch blasting away had the gas come out in the ashpan and burn a bit like the coal in a fire.
I'd very much like to get this sorted in memory of my old mucker so please do contact me.
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Post by Andy Clark on Oct 17, 2005 8:33:48 GMT
I hadn't realised that "Dick" was in the list of censored words. Given all that Dick had to put up with, and the tremendous sense of loss that the community reported when he passed away, it is only fitting that we should be able to spell his name properly. I have edited the list accordingly.
Cheers - Andy
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Post by the_viffer on Oct 17, 2005 9:28:48 GMT
Thanks Andy
I don't know what thingy would have been thought.
Part amused, part horrified at the political correctness and wholly delighted to find his mates still think of him now and then would be my guess.
Cheers
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jackrae
Elder Statesman
Posts: 1,333
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Post by jackrae on Oct 17, 2005 10:31:24 GMT
Bruce Engineering used to sell ceramic burners for locos
I believe they are now called PollyModel
The ceramic ones are a bit less "sledge hammer" than the conventional "jet engine" style of burner and therefore probably consume a lot les gas for equivalent heat output
jack
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Post by doubletop on Mar 12, 2011 10:14:57 GMT
For the record, and rather than repeat it all here, here is a link to my Rob Roy story which includes gas firing. And coincidentally used a ceramic burner that I believe came from Bruce Eng back around 2000/2001 1990/1991. www.homemodelenginemachinist.com/index.php?topic=9516.0I had problems with lack of secondary air so cloned the burner with additional airways running through it. Pete |
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Post by paulingram on Mar 16, 2011 18:54:59 GMT
I did look into this a few weeks back for a 5" model. Bruce Engineering state in their catalogue that the ceramic burners are not really suitable for passenger hauling locomotives. Also a web search revealed accounts of anaemic steaming using this approach. Somebody did point me towards an american site where the author had gas fired a big 7 1/2 gauge loco. I wrote to him for some info and he pointed to a US supplier of gas burners: www.locoparts.biz/The individual burners run 5000 to 6000 BTU, add as many as needed to get the desired heat output. Unfortunately the burners are manufactured in the USA and run $18 each. I did find this site showing how to make an equivalent: www.livesteam.org/MartyBurners/index.htmThe main thing is to work out how much steam your logo needs, convert that to BTU and that will tell you how many burners you would need. Gas firing apparently also requires modifications to blast pipe and blower to reduce their efficency otherwise you run the risk of sucking the fire off the burner. Obviously, I havent actually done this, just thought I'd share what I found. Hope it is helpful Paul |
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Post by doubletop on Mar 17, 2011 9:36:40 GMT
Paul You've raised some interesting points. The problem with ceramic burners is getting 'secondary air' into the firebox without compromising the size of the ceramic. My original Bruce burner had this problem and I overcame it by cloning it with additional air holes through the middle new on the left original on the right.  ![]() i747.photobucket.com/albums/xx112/doubletop/Rob%20Roy/DSCF5726.jpg[/img]Ceramic burners may only be useful for smaller guages The issue of drawing the flame off the burner can be dealt with by putting a baffle (arch) on the front of the burner. I used a piece of stainless sheet.   My first attempt at making a new burner with greater secondary air capability was based on a design used successfully by other club members. They got the design from a US magazine article from the 80's by a Canadian guy.   My attempts didn't work to well so I went back to ceramic The Marty Burners look extremely promising and look like they would work well allowing the right amount of gas and air flow. Worth further investigation. The link Paul provided didn't work. This one does www.livesteam.org/MartyBurners/. They certainly look like they'd be up to 7,1/4" locos. On the number of BTU's here is a link to a table that indicates the BTU's you get for a given gas type, jet size and pressure. www.joppaglass.com/burner/highp_chart.htmlGet the jet, gas pressure and air mix right and you are way (yeh right!)I have a pressure gauge in my setup to give me an ideas how much heat I am producing (relatively that is)  Hope that helps Pete |
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isc
Statesman
Posts: 708
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Post by isc on Mar 17, 2011 10:44:00 GMT
Pete, what metal did you use to make the all metal burner ie., the one without the ceramic burner. isc
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Post by doubletop on Mar 17, 2011 19:50:43 GMT
It was just copper tube. The cross pipe is just a standard plumbing 15mmx 22mm T piece. A couple of cooper sheet caps silver soldered on each end and 19mm tubes for the burner tubes. the Rob Roy firebox is 44mm wide with 2 x 19mm tubes it gives enough room for 3 x 2mm air gaps one on each side and one in the middle. 22mm would have been too big.
Hope that helps
Pete
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isc
Statesman
Posts: 708
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Post by isc on Mar 18, 2011 11:37:11 GMT
Pete, going by my limited experiance making burners for my hot air engines, I would say that the design is OK, but I would change from copper to steel, or better still stainless, the copper conducts heat away from the flame. The holes look fairly large, I would use smaller holes, And more of them. You can always make the holes bigger if need be, don't know if a balance tube might be needed at the far end of the burner tubes. I presume that the ceramic burners give a good amount of radiant heat from the glowing ceramic as well as heat from the flame, this is proberbly a better burner. isc
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Post by doubletop on Mar 18, 2011 20:56:19 GMT
Isc: I agree with you completely.
On the tubular burner; I used copper because that's what I had for 19mm tube. The holes are too big, I copied the drawings given to me by the local guys who had been successful. The burner was worse than the original Bruce Eng burner, so I went back to that. With some work on hole and jet sizing the tubular burner should very workable. Do it in stainless and even better. I've prototyped burners in copper in the past and once they have been successful remade them in stainless.
Again; the clone of the Bruce Eng burner was done in copper because that's what I had. The ceramic was from Bruce Eng (purchased in the past year) and just about matched the ceramic in the original purchased about 20 years ago. The Clone is successful but now I've got it going I've plenty of other things to get sorted on my Rob Roy before I remake it in stainless. I may even have another go on the tubed version.
I do like the look of the Marty Burners, posted by Paul they get the flame up into the firebox. My original tubular burner was flat so at the height of the foundation ring and I had flames coming out of the side. Mk2 had the crank in the air tube to try to overcome this. The Marty burners wouldn't have that problem.
BTW
On the subject of jet sizes and BTU's. The Marty burners say they are 6000 BTU's at 5 PSI on propane. They use a #71 drill for the jet. In the table I posted #71 and 5 PSI states that should be about 16000BTU's.
Anybody able to offer any clues why they should be different?
Pete
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isc
Statesman
Posts: 708
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Post by isc on Mar 19, 2011 12:16:01 GMT
On one of my burners I drilled the jet with a 1mm drill, and used a darning needle to make an adjustable jet, it works quite well, but my burner requirement is much less than what you need. The burner is a dough nut shape that fits around the displacer cylinder of the motor, the inside(burner surface)is 2" dia x 1" high with 3 rows of 1/16" holes, can't remember how many, proberbly about 20 each row.isc
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Post by doubletop on Mar 21, 2011 8:16:16 GMT
We managed to get all the planets aligned and we had the loco, camera, weather and assistants in the same place at the same time. Our track is effectively two concentric rings with the 7.25" gauge track running around the outside of the 3.5"/5" raised track. One of the guys co-opted the driver of one of the club locos to follow me around. So here's a few laps of me with "Harry" doing its thing. Things were going well so one of the larger gauge loco owners suggested that I should try with a bit more of a load. So a riding truck was rolled out and tagged on the back with the intention of doing a few laps with it. The boys couldn't resist a photo opportunity so all jumped aboard.  It was meant to be a bit of a joke shot nobody really expected it to go anywhere did they? OK; it needed a bit of a helping foot to get it rolling, then again there's a lot of oil on the tracks in the station area as a result of locos starting out with their drain cocks open. The bend it stopped on has always been "Harry's" nemesis as there is a slight rise at that point. Train weight. The loco is 18kg, I'm 100kg and the driving trolley is 35kg. Dave on the front of the passenger car said he's around 70kg so lets say they are all 70kg and then the passenger car lets say 20kg so that's 453kg total or 996lbs with gas bottles, water etc I think we can call it a round 1000lbs. That's a ceramic burner on a Rob Roy Pete |
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Post by doubletop on Apr 6, 2011 20:32:15 GMT
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