Poker Burners

495 Views 9 Replies 5 Participants Last post by Jeff Williams, 6 d ago

robertyj

Discussion Starter · 11 d ago

So how does a poker burner actually work?

I think I understand the basics. Gas is emitted under pressure through a fine jet into a venturi tube that causes air to be mixed air with the gas. The gas then emerges through holes in the burner to be ignited (or not). The flame can fail for a number of reasons: too much air, too little air or too much pressure at the burner causing the flame to blow itself out.

So far so good but it the interplay between the variables that I'm trying to get my head around. The variable are:

1. Pressure from the tank - determined by temperature. and gas valve setting.
2. Size of the gas jet - bigger means more flow but less velocity therefore pulling in less air
3. Size of the opening in the side of the venturi tube - controlled by a choke
4. Size and number of holes in the burner.

The reason for asking is that I struggle with butane fired locomotives and the most common problem is that the fire won't pop back to the burner and settles in the smoke box. My recent experience with the Regner Paul was the worst so far but I also have a couple of butane fired Asters that exhibit similar issues - albeit less acute.

Any thoughts or references to material online would be much appreciated. Trial and error is fine, but I always like to get back to the basics.

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Pete Thornton

· #2 · 11 d ago

I'm afraid a lot seems to be trial-and-error. The Regner Paul has a particularly short boiler but uses the same length poker as their other locos - maybe length of the burner is an issue (#5? Or is that the 'size'?) The advice for the Aristo Mikado is to cover 1/3rd of the burner presumably to make it shorter.

#3 is the interesting one. I'm told you can make the flame pop back by putting your finger over the choke hole.

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David Leech

· #3 · 11 d ago

Robert,
Before I converted it to alcohol, the only way I could get the poker burner my Aster NYC Hudson to work, was to pull it out into the cab, light it from there, and then use a suction fan before I pushed the burner back into place. At that point the fire seemed to know where it was supposed to be!
At that point, I also decided that gas was NOT my preferred method of firing, and only have alcohol fired locos!
But others seem to get on with it fine, so it is just a mind set thing I guess.
Cheers,
David Leech, Canada

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robertyj

Discussion Starter · #4 · 11 d ago

David Leech said:
Robert,
Before I converted it to alcohol, the only way I could get the poker burner my Aster NYC Hudson to work, was to pull it out into the cab, light it from there, and then use a suction fan before I pushed the burner back into place. At that point the fire seemed to know where it was supposed to be!
At that point, I also decided that gas was NOT my preferred method of firing, and only have alcohol fired locos!
But others seem to get on with it fine, so it is just a mind set thing I guess.
Cheers,
David Leech, Canada

David, I'm with you on preferring alcohol burners. The irony is that I got the Regner Paul as something simple and easy to take to events. It has turned out to be anything but. I do finally have it working by reducing the area of the brner and covering what reamains with a stainless steel mesh

Robert

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yellow_cad

· #5 · 10 d ago

Pete Thornton said:
The advice for the Aristo Mikado is to cover 1/3rd of the burner presumably to make it shorter.

Pete, could you please elaborate on this. What is the ill affect of the longer burner in the Aristocraft Mikado? How is the 1/3 best covered? Should a screen still be used? Does the 1/3 rule apply in all cases? Thanks Jim

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Pete Thornton

· #6 · 10 d ago

yellow_cad said:
please elaborate on this.

Jim, I have no idea. I got this from a thread on the Mikado.

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yellow_cad

· #7 · 10 d ago

Pete, do you happen to have a link to that thread? Thanks, Jim

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Pete Thornton

· #8 · 10 d ago

yellow_cad said:
do you happen to have a link

Jim, it was your thread.

Need some help with a Aristocraft Mikado 2-8-2

I just acquired an Aristocraft Mikado that had survived a smoke box fire. My real issue is the igniter. I can't tell if it is working. I have not gassed it up though. Is there a way to tell if it works without igniting gas? If it does not work, what is the next best way to light this thing...

www.mylargescale.com

Lotsasteam [Manfred] posted "block off 1/2 inch of the burner slots" so maybe I was wrong about the 1/3rd! Nick Jr. also had some ideas about mesh on the burners.

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yellow_cad

· #9 · 10 d ago

Thanks Pete. I understand that concept. Jim

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Jeff Williams

· #10 · 6 d ago

If the butane is burning in the smokebox, that indicates to me that there isn't enough air mixed with the butane for it to burn in the poker burner.

I apologize if the following suggested steps are obvious to everyone and that these steps have already been tried.

First, does the burner work when removed from the locomotive? That is, does it generate a flame from all of the slots in the poker? Is the size of the flame controllable by adjusting the fuel valve? If not, there likely is a mismatch among jet size, venturi air vent size and poker length/number of slots.

Second, try opening up the choke in the side of the venturi tube to allow more air to enter the burner and mix with the butane. Also, reduce the butane valve opening to be sure that the butane supply isn't overwhelming the air supply.

Third, be sure that the jet outlet is located around the center of the venturi air inlet hole to that air is being sucked into the poker burner and not pushed out.

Fourth, try a smaller jet size so that the butane stream has time to mix with the air to allow combusion.

Fifth, see if there is a clear hole or path to allow air to enter the flue from the poker-end of the flue. On Accucraft models, in addition to the air holes and choke that allow air to enter the inside of the poker burner to mix with the butane, there sometimes is a hole, drilled through the jet holder flange that allows additional air to enter the rear (jet end) of the flue, between the outside of the poker burner and the inside of the flue.

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