Intro & Burners   Valves   Control   Gas Supply Technical The Fire Grid began as what could only be called a vision. I was working on controllers for an audio art project and just suddenly saw what could happen if you connected a pressure sensitive touchpad to a grid of flamethrowers. The vision was great, but the refinement of the technical details turned out to be about three orders of magnitude more difficult than I'd thought at first. I am (fortunately) enough of a geek that I actually enjoyed the process, or most of it at least.   Burners There were two design challenges in creating the fire grid burners - I needed a burner that could produce anything from a small blue (oxygenated) flame to a large yellow (unoxygenated) plume. I also needed to have a blue flame that was stable in wind, which they normally aren't. If you take a cigarette lighter and adjust it so that it puts out a blue flame, you'll find that the slightest breath of wind will extinguish it.   The solution was to create a vortex flame. Vortexes are stable in wind if they're strong enough, so that even the blue flame could remain lit in a crosswind condition. To do this, I designed a burner that had a central gas feed and a pressurized air feed as well. You'll notice in one of the pictures above that each burner has four screws protruding from its top. Those are air jets, blowing horizontally and arranged to create the vortex for each burner. The air feed also solved my other problem - how to make the burner transition from a blue flame to a yellow one. A precise amount of air is fed into the gas stream at the center of the burner. At low flows of propane the air will be sufficient to oxygenate the flame and turn it blue, but at higher propane flows there won't be enough oxygen and the flame will be yellow.   The burners were built from a combination of CNC machined and store bought parts. Their brass and copper construction, combined with the lifting effect of the vortex, enable them to run very cool while putting out large amounts of flame.   I'm pretty proud of these things, to be honest. They were a piece of original thinking that I hadn't expected when I first started the project, but in the end they worked out quite nicely. I like the way they look as well - sort of a bright, sunny, industrial look.