Posted by Rick on January 15, 2008, 6:42 am, in reply to "Dietz 39 burning characteristics (part 2) + adlake burners"
While it is still fresh in my mind, I thought I'd throw in a few words about wick trimming and operation.
You can get some interesting flame shapes by varying the wick trim.
If you hold a penny against the wick and use that as a guide, you can get a nice, single lobed flame with a single point on the top.
If you make a sharp point on the top of the wick (each side about a 60 degree angle), and then cut the point off near the top so that it leaves about 1/4 inch flat spot on the top, you can get a really tall, narrow flame.
However, if you want to get maximum light out, trip it perfectly flat, and then cut the two edges with a tiny 45 degree angle. In fact, if you ever let a fount burn empty, or trim the wick by dry burning it, this is pretty much the shape you will get. It is the same shape as the burner cone.
Whatever the trim, after you cut the basic shape, go back and be anal about cutting off any fuzzies. They will cause little flame imperfections. Rather than using something that saw prior use cutting who knows what, I use a pair of shears that I bought just for this. They have tiny serrations on the blade, which help cut the little fuzzies rather than letting them slide out from between the blades. If you were working on a road crew your boss would probably fire you for being anal about it, but it only takes a few extra seconds and the result is generally worth it.
Flame height - if you run the flame just short of the smoke point, it will need constant adjustment as it warms up for the first 15-30 minutes. Once it is warm, if you keep an eye on it and run it attended, you can get away with running it right below the threshold of making smoke. However, don't walk off and leave it like that. YOu will find that over time the flame will go up over he smoke threshold and you will have to back it down a bit every now and then. I believe this is due to the fule leaving the fount and being replaced by air. The fuel I think keeps things cool. Air, having a lower specific heat than kerosene, does not cool well and the wick begins to heat up. The hotter wick passes warmed kerosene and makes the flame gradually grow. Generally you will get a runaway somewhere after the fount is half empty.
What I found is that I can get a flame height with a flat trim that is about 1.25 inches high before it smokes. However, it will run away at this setting if left there. Long term, backing it down to about 3/4 of an inch seems pretty safe. I have not experienced a runaway at this setting to date... a couple dozen fount fulls at least.
Rick
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