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"Notes from the Unit Shop"

 

Kevin O'Connor's advice for the beginning small scale live steamer

 

Radiant Poker Burners

 

 

 

Aster  /  L G B Frank S. burner

 

 

 

Aster Hudson burner 

 

 

 

Aster Big Boy burner

 

As delivered the Aster Big Boy Burner was a three element burner, but as you can see it is now a two element unit that puts out way more heat energy than the locomotive can use. That is a Charm-Glow gas lighter in the vacant third hole in the burner body. That is how I light up the locomotive during regular operation.

 

Art Walker and others were referencing the use of ceramic burners in pot boiler configurations whether they were vertical or horizontal.  Someone, I forget who, sighted the problem of making a poker type ceramic burner.  He would be right as it is a problem, but there is another approach.  

 

One must ask the question "What is so special about ceramic burners that I would want to build one"?  The simple primary answer is that they are roughly 100% more efficient than the standard blue flamed, Benz-O-Matic type burners (whether gas ring or poker type) that are commonly found in Aster, Roundhouse, Pierce, and AccuCraft gas fired locomotives.  Why is this so? In high school physics we learned that there are three ways that heat travels; conduction, convection, and radiation. 

 

The standard burners I mentioned above only use two of these paths to conduct heat to the boiler's flue; conduction (poorly) and convection (hardly at all).  Only the properly operated ceramic burner utilizes the principal of radiation, and as a result becomes very efficient in converting gaseous fuel into easily transferred heat energy.  The key to this discussion is not the materiel that the burner is made from, but rather can the burner be made to radiate using whatever materiel that the burner is made of.  The answer, especially in the case of poker burners, is an unqualified yes!
 

Five years ago I built the first (that I know of) radiating poker burner for my Frank S. locomotive.  It all started with a device that I christened "Turbulator".  The first Turbulator was a piece of 20 mesh stainless steel fabric that I bent into a triangular, yet helical, shape, and then sewed it onto the end of a standard Frank S. blowtorch type poker burner.  The "thread" was .015' diameter stainless steel wire.  The turbulator was about 1 1/2" long.  When the burner was operated, and the system came up to temperature, the Turbulator (being located out in front of the bright blue flame) started to glow a dull red. 

 

As conditions in the flue stabilized I found out that by turning the gas flow down that the Turbulator's color changed from dull red to medium orange!  Huh!  How can that be?  Well, truth be know, the first amount of gas flowing out of the burner was in excess of needs, and it was not all burning up in the blue flame, and further, it was COOLING THE TURBULATOR as it passed on to the smokebox and out of the stack.  By reducing the amount of gas flow, thus conserving the supply, the Turbulator came up to temperature (medium orange) And RADIATED all of the heat generated by the burner directly into the dark colored walls of the flue (Law of the Black Body).   

 

I know someone is going to say "All of the heat"?  Yea, it is an exaggeration, but in one on one comparison with the non-turbulated burner, not by much.  In fact one could now hold one's hand directly over the smokebox stack without feeling much waste heat emanating from the stack.  The Frank S. runtime went from 35 minutes to 65 minutes using the same amount of fuel!   Since that time I have built many radiant poker burners, and over time the designs evolved into the present types that I have fabricated for Aster Hudsons, K4s, C&S Moguls, Western Marylands, Climaxs, Big Boy, and Rubys and butane Janes.  My personal Big Boy runs with much power untapped on two radiating poker burners instead of the three standard burners supplied.  In fact the third hole in the burner holder in the Big Boy contains a Char-Glo gas barbeque lighter element that allows the burners to be lit with the push of a switch!
 

The "magic" materiel that I use to make the radiating poker burners is stainless steel mesh of about 40 to 50 denier that is tightly wrapped around the poker burner's slots and is held in place by either a tightly fitting sleeve ala Ruby practice (I developed this configuration for AccuCraft in the spring of 1997), or by binding it in place with .015" diameter stainless steel wire wrapped around the poker like barrel bands.  Just this much work will improve a "bad actor" burner, but it will not radiate heat. 

 

The radiant component is supplied by cutting a strip of #20, or so, stainless steel cloth long enough to cover all the burner's slots from end to end, and wide enough to equal 3/4s of the circumference of the cloth wrapped poker diameter.  This piece of cloth is rolled up into an arc approximately the same diameter as the poker burner, and is then sewed onto the poker using the lowest second course of stainless steel threads (running fore and aft) as the attachment point.  This configuration resembles the top cover of a Conestoga Wagon, and there is an air space of about an eighth of an inch between the top of the cloth wound poker and the bottom of the 20 mesh cloth.
 

In practice the burner is lit on the lowest fuel valve setting consistent with keeping the flame lit in a cold flue.  Once the flame steadies out the fuel control valve is opened slowly until the "Conestoga Wagon" top starts to glow red.  At this point the operator lets the glowing mesh temperature stabilize, and then opens or closes the gas control valve until the desired color is achieved.  Consistent with the load imposed on the locomotive, the darker the color the better as lower mesh temperatures improve the life span of the incandescing mesh.
 

At the Summer Steamup in Sacramento this year I provided a fill in seminar on radiating burners.  I borrowed a radiating burner that I had fabricated for Sam DiMaggio's Aster K4s as my demonstrator, as well as an example of the first Frank S. unit with a newer model of the original Turbulator attached.  Sam did not time the runs of his K4s, but he did repeatedly time his Aster Hudson which has a nearly identical radiating poker burner in it.  His run times, with the Hudson, on the same amount of fuel, pulling the same load, more than doubled to in excess of 65 minutes including starting from a cold boiler with no topping up the fuel tank prior to gaining the right of way.
 

Now that the cat is out of the bag I hope that others will experiment with stainless steel radiant poker burners in their locomotives.  One more thing!  Once a poker burner is converted to a radiant type its dynamic fuel requirement drops so low that the burner becomes SILENT (or nearly so).  This is a disadvantage to those who have learned to operate their locomotives by ear.  From now on they will have to learn to drive a locomotive by the boiler pressure gauge and by observing the locomotive's behavior both with and without load. 

 

I hope that I have not confused anyone, and that this information will help to further the enjoyment of the hobby.  Obviously there is more to this stuff than I have written, but I have covered all the principles.  Others can duplicate what I have done over the past five years in their own shops using only hand tools and following the above guidelines.   

 

Radiant Burner Research Continues

 

I am now working a gas firing presentation for Diamondhead 2003.  Here are two photos of a radiant burner model-engineering prototype for a vertical boiler.  Presently, I am building one for my Aster B&O Grasshopper.  It is a very unusual design! 

 
    
 
 

 

 

 

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