The inner parts for one of the two flue burners:
- outer tube with air openings
- inner burner tube with baffle
- threaded gas jet nipple
The nipple was the most finicky part to make, with a 0.6mm (24 thou) hole exactly in the middle - and it has to be exactly straight, to boot! My lathe's top speed of only 2500 rpm was a little on the low side, so I had to make a few tries to get it right...
An assembled burner - I didn't bother pickling it after silver brazing, since it will be hidden and will be oxidised by its own heat anyway...
The nipple is screwed into the back wall of the burner, and the gas enters through a 4.8 mm copper-nickel pipe, the other end of which will be connected to a shut-off valve.
You can see the ignition tube (for the sparklers, just as on the 3003) and the two larger baffles that will hold the burner centered in the flue - and keep the combustion gases from entering the cab...
This is the glow-net cone, quickly made of stainless steel mesh, 0.5 mm (20 thou) wire, spaced 1.5 mm. The front end is simply crimped together, and the whole thing is held together with a few SS wire lacings. Over its length it has three spacers (made by folding strips of SS mesh to flower-petal shape ) which will keep it centered in the flue tube. These mesh cones are "consumables" and will have to be renewed after approx. every 200 kilometers of running, i.e. once a year or so, for me...
A first test of a burner in the flue - after some adjusting of the inner burner tube's position, I got a very nice flame that heated the mesh to a bright orange, here seen from the smokebox end.
From the gas consumption of 0.6 kg/h (dependent on gas pressure and nipple diameter, info taken from a table included with my Sievert burner) the heating effect can be estimated as 7.5 kilowatts per burner. Two burners will provide ample heat for this little 0-6-0 loco's boiler, which has a total volume of 7 liters.
With a working pressure of 7 bars / 100 psi, the boiler's power will not exceed the 50 bar-liter limit over which I'd have to get an official test certificate in order to operate the loco in public here in Finland...