Problem with Accucraft Ceramic Gas Burner in C25 locomotive - myLargescale.com > Community > Forums


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Old 03-09-2020, 10:53 AM   #1 (permalink)
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Default Problem with Accucraft Ceramic Gas Burner in C25 locomotive

The following problem showed up this weekend with the ceramic gas burner in our C25 locomotive. As i have limited experience with ceramic gas burners, I am hoping someone here on the forum can assist with our troubleshooting of the situation...

Description of loco and problem:

This is an Accucraft C25 purchased as a coal fired model...Model has been fired successfully using coal as fuel. We also purchased an auxiliary ceramic grate/burner and extra gas tender. The ceramic grate was properly installed in the firebox for use with gas. Gas used is propane/butane mix. Adjustable fan was used on stack for draft.

Upon gas firing, all appeared well with ceramic radiant burner...within 15 seconds the top of ceramic burner was glowing red. All fine until boiler showed about 20 lbs pressure...at that point a "pop" was heard and the top of ceramic burner lost red glow...fire appeared to be underneath ceramic piece rather than on top of ceramic. Within a minute or two the sides of ceramic burner (not the grate) started to glow dull red confirming fire underneath ceramic. Gas was turned off, loco allowed to cool down. Situation was repeated several time with same result.

Variables attempted:
1) Varied amount of gas without change
2) Varied amount of fan speed with same result
3) Tried adding blower on engine instead of fan at 15 lbs....same result.

My logical guess at this point is that once the ceramic burner gets hot enough the fire moves from top of ceramic (radiant) to underneath ceramic in burner box.....but why?

Has anyone else had this happen, and if so what was your fix?
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Old 03-09-2020, 05:31 PM   #2 (permalink)
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Cliff,
Have you tried talking to Accucraft?
I know nothing about gas!
But, as a suggestion, can you remove the burner from the locomotive and test it separately?
See if after a period of time the same thing happens, or hopefully not.
If all is okay, then I think that you are correct and as it gets too hot, it allows the gas to ignite under the ceramic.
Maybe it needs more air to circulate to keep it cooler?
Good luck.
David leech, Delta, Canada
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Old 03-10-2020, 07:04 PM   #3 (permalink)
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Cliff.....the ceramic material must be sealed {airtight} to the edges of the burner box. See if that

is the case with your burner....
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Old 03-11-2020, 09:10 AM   #4 (permalink)
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Cliff
I had the same problem when I first started using ceramic burners.
Apparently, the gas/air mixture in the burner box will ignite at about 900F
I changed the ceramic material to that from Bruce engineering in the UK
But because other Accucraft engines haven't had this problem, i would think it is something else.
You shouldn't need a mixed gas with a ceramic burner and since it burns hotter than butane, that could be the problem.
You have probably damaged the box by now so you need to remove it and inspect it and the ceramic material and as Sal said make sure there is agood seal around the material. I use high temp RTV for that
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Old 03-16-2020, 10:01 AM   #5 (permalink)
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Bill / Sal:
Thank you for your comments...I used some 1/16" ceramic sheeting I had to provide a temporary tight seal around the perimeter of the ceramic burner....this along with switching out the jet to another #5 seemed to have solved the issue as the fire is now staying on top of the ceramic.
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Last edited by clifforddward; 03-17-2020 at 11:10 AM.
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Old 03-16-2020, 03:46 PM   #6 (permalink)
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Cliff,
Which do you mean?
It is NOW staying on top, or NOT staying on top?
Glad you fixed it.
David Leech, Delta, Canada
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Old 03-17-2020, 11:11 AM   #7 (permalink)
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Sorry David, mis-typed....meant to say "fire is now staying on top of the ceramic..." I've gone and edited my post.
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Old 03-19-2020, 07:05 PM   #8 (permalink)
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Seal any gaps around the edge of the ceramic insert with furnace cement. Some stainless steel scrubby material to fill the space under the ceramic has also been used.
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Old 03-20-2020, 06:16 PM   #9 (permalink)
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I've got a ceramic burner in my DJB Engineering Class A Climax. I had the same trouble. When I sealed the ceramic material to the copper burner with High Temp RTV it caused the ceramic to crack due to differences in thermal expansion between the copper and ceramic. Once the ceramic cracked the flame burned under the ceramic material resulting in a loss of heat output and an increase in noise. I used some furnace cement to block the ceramic holes around the perimeter to cut back on heat output. Gas flow rates at very low burner settings had decreased causing the flame to burn under the ceramic. Blocking off holes increased the flow rate at low settings, problem solved.
I've had similar problems with poker burners. I consulted with Rishon Locomotive Works on this issue and the rule of thumb is that burner slot width or hole diameters should be less than the wall thickness of the burner tube or pipe. Lining the inside of the tube with fine mesh screen is a way around this problem. A plug can be placed in the burner tube to block off slots at the smoke box end of the poker as well. This was done on my Class D Shay poker and increased run time to 3 hours on one take of gas.
Keep 'em Steamin'
John

Last edited by bonzo1953; 03-22-2020 at 12:26 PM.
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Old 03-26-2020, 04:37 PM   #10 (permalink)
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haven't read all here so may duplicate.

Use boiler insulation packed in fairly tightly. I think it's too much secondary air supply. Just a hunch. best of
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