Having finished making a meths burner for my BSA Mamod which certainly supplies enough heat for it to work well on a cold windy day. Thoughts were given to making a gas burner for the same model, there was enough room left on the footplate for a gas tank, in fact a part built tank has been fitted. There had been no intention of making a burner in the near future however I came across an old burner made by Merlin in the 1980's as a conversion kit for a Mamod.
These burners were very inconsistent in how well they worked mostly they didn't work that well the brass/bronze mesh becoming clogged or melting, if they did work and the boiler ran dry they quickly destroyed the gauge glass and any '0' rings used on the boiler and they could also melt the soft soldered join on the boiler and the boiler bushes could come loose. There were also other problems with gas tank seals and the silicon tube used to supply gas to the burner.
Anyway back to the burner I found, it had had some work done on it the original mesh being replaced with a Nichrome one.
The burner works reasonably well but there is still a lot of yellow in the flame and most of the heat is at the front end of the burner.
A member of the forum suggested to me that fitting a small size jet might help and possibly reduce the heat output of the burner. I was a little sceptical, I could see that it might make the burner more controllable but given the same amount of gas going either jet into the burner there shouldn't be any difference in the heat output. However I am a great believer in trying something to see what happens, slapped faces have resulted in earlier efforts but that was a long time ago! The original jet fitted to a Merlin burner is I think a No.8 so I tried the smallest I had which is a No.3 the burner lit but didn't have much of a flame. The next size up was a No.5 which does supply enough gas and is certainly more controllable than the original jet. The flame however was still quite yellow an indication that there wasn't enough air in the mix so an extra air hole was added to the burner tube.
The No.5 jet modified to fit in a new slide fit jet holder.
The burner with its extra air holes and jet fitted. The original jet was held in place with a screw which allowed its position to be adjusted I prefer the jet to be a slide fit against a shoulder which means when it has been removed for cleaning it goes back in the same place. The lack of screw also means this is easier to do, the pipe holding the jet in place.
These alterations certainly give a better more uniform burn.
To fit the burner to the model a more substantial bracket which didn't need nuts was made.
Test run using a separate gas supply on a very damp day.
Video.
HTML
<embed width="600" height="361" type="application/x-shockwave-flash" allowFullscreen="true" allowNetworking="all" wmode="transparent" src="http://static.photobucket.com/player.swf" flashvars="file=http%3A%2F%2Fvid895.photobucket.com%2Falbums%2Fac154%2Fgaynorandtony%2FVideos%2FMVI_1935_zpssuthjivv.mp4&title=">
IMG
Regards Tony.
