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Old 09-27-2010, 09:35 AM   #1
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Default Ceramic Gas burners on Locos

I'm using a commercial ceramic gas burner on my Rob Roy loco for the first time and I am having trouble getting anything like a good steam pressure.

http://www.homemodelenginemachinist....p?topic=9516.0



I've worked out to start with a low flame to get things heated up before slowly opening the gas valve to get more heat. Should I have the fire door open or closed and should I be using the blower to get some air flowing through the system.

With the fire door open I can have have flames shooting out the door, so I've closed it. I then open up the gas to the point there's probably to much gas and it flashes over and either goes out or I have a moment and shut down, just in case. Sometimes the burners ceramic block glows orange other times I'm just getting a blue flame. Is it the orange glow or blue flame I need.



Any clues on how I should be doing this please?

Pete



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Old 09-27-2010, 10:03 AM   #2
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Default Re: Ceramic Gas burners on Locos

Pete

I hate to say it but the burners are not big enough. most people just use open jets with out the ceramic bit, yes use the blower

you will need enough heat to lift the safety valves with ease and keep them blowing off for at least 10 mins ( for the accumulation test ), note that your boiler is flued for coal not gas fired , ie the flues are to small

a Rob Roy in steam on the track needs a good fire going to maintain its steam any way


Sorry I cannot be more help , I have driven but not owned a Rob Roy , I did have a "William" which also have to be fired to the bottom of the door



Stuart



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Old 09-27-2010, 01:46 PM   #3
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Default Re: Ceramic Gas burners on Locos

Hi Pete,
Ceramic burners generate radiant heat when they are glowing orange, and should produce the maximum amount of heat in that condition.
Regards,
Gerald.

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Old 09-28-2010, 05:08 AM   #4
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Default Re: Ceramic Gas burners on Locos

Stuart

I think you've confirmed my suspicions; this burner just isn't going to do it. I was having these concerns running in my garage, our club track is on the beach in sunny windy Wellington.



So its out with the ceramic burner and re-install the ash-pan and grate. That saves me a bit of time I could have wasted trying in vain to get it to work. The guys in the club can show me how to fire it up.

Gerald

I had thought that may be the case it just wasn't consistent enough to rely on it. Any bit of a draft and and the flame was all over the place and at times more outside the firebox than in.

It's gone

Thanks guys

Pete

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Old 09-29-2010, 02:37 PM   #5
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Default Re: Ceramic Gas burners on Locos

Hi Pete,
Most of the ones using the Ceramic Gas burners that I know are in Gauge 1 Locos or in Model Boats. I think that the air supply has to be very well controlled and brought in with the burner. There have been a number of them around here (Toronto, Canada) that have gone to gas burners, but I haven't looked too close to there designs as they are too large for my models.
Regards,
Gerald.

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Old 10-25-2010, 09:36 AM   #6
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Default Re: Ceramic Gas burners on Locos

I had given up on the ceramic burner idea and refitted the ash pan and grate when one of the club members gave me a call and put me in touch with a group of Kiwis who are successfully running their locos on propane. One of them another Rob Roy and one a large 5" gauge loco.

I went round to Dave's place and we got the ceramic burner running and he was pretty happy with what he saw. Eventually we got it up to 80psi. The result of the session was a series of mods I had to do to improve things.

I've been getting better at getting steam pressure up and keeping the whole lot alive. Yesterday I managed to get a cold engine, with a cold fill, up to 80psi in about 10 minutes. It was outdoors with a bit of a breeze going. So pretty encouraging.

I'll post the pictures back on the Rob Roy thread when I get a bit of time this week.

Pete

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Old 01-03-2011, 07:46 AM   #7
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Default Re: Ceramic Gas burners on Locos

I got a PM from Tups (Cris) for more details on the replacement ceramic burner I have made. This one works and if I don’t forget to open the blower before I stop running it doesn’t go out.

Some of this is a repeat from the Rob Roy thread but for completeness I’ll do it again here and hopefully by the end it will all make a bit of sense;

The problem I had been having with running my loco successfully on gas was although I could get the engine up to pressure relatively easily maintaining it was a problem so I ended up going round the track in short runs followed by a recovery of pressure then on again. On the assumption that the more heat you can get into the engine the more steam you make and keep up the pressure. I have been experimenting with burners and learned something from the exercise. Some of it is blindingly obvious but it has helped me understand what is going on, or not as the case may be.

The basics being.
· To get more heat you need to burn more gas (I said it was blindingly obvious stuff)
· The amount of gas you burn is a factor of jet size and jet inlet pressure.
· You need the right balance of primary and secondary air to ensure complete combustion (its about a ratio 1:24 gas:air for propane (4%:96%)
I made myself a test rig so I could see what was going on. Regulator on the gas bottle, Input pressure gauge and output pressure gauge after the gas tap

Gas Control Rig



The assumed problem with the ceramic burner was that it couldn’t get enough secondary air. If it is running on the electric blower its fine, on the steam blower it’s fine. But add more gas and the engine whistles like kettle as it tries to draw air through the holes on the firebox door. If the pressure is too high, and the blower is off, it flashes back with a huge pop or just goes out. If it goes out there's no indication as you can still hear the gas flowing. Not good

My starting pint was the local guys who had given me a lot of advice based on the success they had with gas firing their loco’s.

First was to put a baffle on the front of the burner to keep the flames in the firebox for a while rather than shoot straight down the fire tubes. This keeps the heat where you need it and stops you melting the paint on the smokebox. Believe me it works, I ran the loco once with it out and the smokebox paint job looks a bit sad now.

Stainless Baffle on original burner



Baffle in the firebox, note its at the fire tube end not the fire door end.



(I am convinced this is a major contributor to success)


The next was make a new burner I started with making a new burner based on some old magazine articles, the intention being that the gaps between the tubes would allow enough secondary air.



This didn’t work too well and made a couple of versions but they just didn’t give the heat and there was lots of un-burnt gas.

New Burner

I then turned to resolving the secondary air issue with the ceramic burner I had seen a version of a burner with tubes running through it. I wasn't about to hack my burner about in case I was wrong so set about making a copy

All the parts alongside the original



New and old




New burner with the lid off



Installed in the loco you can see the baffle in the front



Make sure that the burner is as high up in the firebox as the jet holder will allow e.g hard against the foundation ring.

The dimensions for mine is 26mm high, 42mm wide 85mm long. This just fits in the firebox allowing for the ends of the stays and a little bit of room for the baffle

Through the middle are 2 x 12mm tubes for the necessary secondary air . To hold up the ceramic there are 2 x 15mm sleeves around the air tubes and strips of copper soldered on the inside edges of the body.

The jet holder is 38mm long 12mm dia brass drilled 8mm for the jet assembly, It is cross drilled with 6 x 5.6mm holes set at about 60degrees. The jet is a #15 held in with 6BA screw. The jet holder is mounted as low as it can be in the burner body. I'm sure it can be longer, as your installation would require.

My original was stainless steel, this one is copper, as that’s what I had. I’m sure brass would be just fine. (either way16-20swg)

I got my ceramic from Bruce Engineering (Polymodel) in the UK

http://www.pollymodelengineering.co....ring/index.asp

It cuts really easily; I did the holes for secondary air pipes by using an offcut and twisting it slowly as it worked through the material.

See these drawings from Sandy C his burner gives a good view of a similar sort of burner albeit smaller and no secondary air holes. However it give you a good idea on sizes. Most of my burners have had some basis on this burner from Sandy and there does seem to be some commonality with parts.

http://www.homemodelenginemachinist....mod;dl=item155

Running with it

As with any loco a blower is needed to get the burner running otherwise you’ll get lots of flame out of the firebox door. I start at about 5-7psi gas pressure with the blower going, it doesn’t need much of a blower, I use a computer fan in a cut down plastic funnel on a long coper tube so the whole lot doesn't melt. That said with the baffle it not like there's flames shooting out of the loco flue.



Once a bit of steam pressure is available (5-10psi) the steam blower can be opened and the external fan removed. As steam pressure comes up more gas can be applied. I find that 20psi max is good for my burner on this loco. It takes only about 10 mins from cold to full steam pressure (80psi), my boiler takes about 500ml of water.

OK I understand there’s a but of reluctance to go to gas burners, but when they work they work pretty well, and clean up at the end of the day is just about zero in the firebox area. And if you have a problem with water, as I have been having on my small loco, no grappling for the dump pin. Just shut down, sort the water, if you've got steam pressure and bit of steam blower and re-light.

Hope that is of use to somebody

Pete

PS

For those of you who missed it, here it is running


Dodgy track at the end caused it to slow and stop
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Old 01-03-2011, 12:06 PM   #8
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Default Re: Ceramic Gas burners on Locos

Thanks very much Pete, that is exactly the information I needed to get started on my own gas burner, hopefully without my usual progression of buying lots of stuff, finding it doesn't work, buying more stuff, finding it still doesn't work, etc etc ad nauseam. My grate is 67x 55 mm, which gives it nearly the same surface as yours, and the boiler is also 500 mL, so performance should be quite comparable I would guess.
In any case, firing a blowtorch through the firebox door just isn't cutting it :-)

Again, thanks a bunch, and enjoy your beautiful loco!
If I manage to actually make something, I'll post onhere.

Cris





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Old 01-15-2011, 06:35 AM   #9
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Default Re: Ceramic Gas burners on Locos

I thought I'd add a bit about gas supply.

The biggest problem I've had with any of the burners I've done, including those for my little engines, has been controlling the gas supply so I know what is going on.

For my small engines I used camping gas cylinders with the 7/16 screw on connector. Primarily because I had a control valve for these cylinders that came with the original Rob Roy ceramic burner.


This didn’t work very well with the loco for two reasons.

  • You have no idea what pressure you are supplying to the burner and you can’t really see what is going on, as the fire door needs to be shut.

  • The gas in these cylinders is 60/40 butane/propane, you really need propane as it provides more heat.

The light began to shine when one of the club members loaned me his driving trolley that is fitted out for gas running. It has gauges so you know what is going on and carries a 2Kg Primus gas cylinder.





The Primus cylinder is ideal as it is a nice size and has a low profile. We get these filled at the local BOC depot and the gas they supply is guaranteed 60/40 Propane/Butane.

You can see the cylinder has a regulator (orange knob on the right) to control the gas pressure and of course the gauges up front to see what is going on. (the grey cylinder on the left is the accumulator for the vacuum brakes.

This led me to get my own set up like this for testing. (I use the loaner trolley for the track)



This has a bottle mounted regulator with a POL connector and input (post regulator) and output (jet) pressure gauges. In addition there is a cut off valve and two gas control valves in parallel. The idea of the parallel valves is one is preset for idle or pilot burning and the second for the main control of the gas supply. The main control can be shut right down without the burner going out. If there is a major issue the cut off valve can be used.

Of course the problem with this is the use of the LPG type bottles with POL (or whatever connectors) they are generally too big and the wrong shape for carrying on a driving trolley.

The other option is the disposable propane cylinders with the “MAPP” connector. I had one of these for a portable barbecue but had no way of dealing with the regulation issue until I started searching on Ebay and found the Turbotorch STK-R regulator. The trouble was they were expensive (~US$60) and the shipping prohibitive in comparison.

http://www.thermadyne.com/IM_Uploads...05_56-1252.pdf

Then I stumbled across this guy in Hawaii who does these and ships worldwide.

http://ultimatespudgun.com/propane-m...tor-p-220.html

US$27 and $12 shipping. It regulates 0-40psi which is ideal when I am trying to get 0-20psi for the burner.



This regulator combined with a pressure gauge now gives me a compact solution for gas supply and control.



The regulator itself provides enough control of gas feed but building this into a driving trolley should really also have a cut off valve and two gas control valves in parallel readily available to the driver rather have them fiddle about with the gas cylinder which can be hidden in the trolley.

There are some issues with these small cylinders
  • They are probably only suitable for smaller locos.
  • They wouldn’t supply enough gas at the right rate for larger locos. They’d cool right down and the pressure would drop off
  • These small cylinders are not refillable and they are more expensive than bottle gas. For example one of these 450gm (1lb) cylinders is NZ$11 whereas a refill of the 2kg Primus bottle is NZ$2.50.
  • Although these regulators fit MAPP bottles I’d suggest don’t even thing about using MAPP gas for your loco.

Of course my other option is the Primus cylinder but I haven’t found a suitable regulator for one of these and these cylinders don’t seem to be current in NZ. I do have a Primus to POL adaptor but when the cylinder, adaptor and POL regulator are coupled together it’s a really cumbersome. Maybe I’ll get something sorted in this area but for now it looks like I’m going the small cylinder route.

Regulators side by side




PUBLIC SERVICE NOTICE – You are on your own with this. It’s up to you to make sure you do things safely and within the bounds of your local regulations
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Old 01-15-2011, 09:49 AM   #10
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Default Re: Ceramic Gas burners on Locos

From my days in G1 I seem to remember dire warnings about using propane!!!
Only butane was recommended. I will try to find more - but in the meantime I suggest you research it as well.
It would be a shame to not to learn from the mistakes of other people.

Chris



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