Cooling design - Re: Steve Jobs -2011

On 11 Oct 2011 at 18:00, allison wrote: I pulled out my Rio Grande catalog, and checked. RG is the big supplier to the jewelry trade here. Lots of very expensive tools, among them laser welders and water torches. The "water torch" section shows several models, all >USD$2000. All use the same electrolyte--KOH: http://www.riogrande.com/Product/Rio-Dry-Mix-Electrolyte-for- Hydroflux-Welding-Machine-or-Rio-Water-Torch/500223 They give a tiny flame that's both a bit lower in temperature (2800C vs. 3500C) than oxy-acetylene (also see: en.wikipedia.org/wiki/Oxy- fuel_welding_and_cutting) and not quite as hot (H2 at near- atmospheric pressures doesn't have a lot of energy density). I've welded Pt- Pt-Rh thermocouple wire (for steelmaking furnaces) and used a standard oxyacetylene torch with a fine tip. We'd scavenge the bits of what was about AWG 20 wire from the 4 foot thermocouples and butt-weld them to make longer pieces for reuse. My depth perception isn't wonderful, but there were one or two guys in the shop who were always dead-on. I did much better with the iron- constantan couples which were very long and used what looked like AWG 12 wire. Methanol is sometimes added to the electrolyte mix in a water torch as a flux when welding precious metals. My friend the flute builder uses 3 electrolysis units with outputs in parallel (one on each phase of his shop supply) to provide sufficient fuel for his work. The benchtop models that use only hundreds of watts typically have a torch tip the size of a hypodermic needle. One reason that the jewelers like them is not for the heat or temperature, but because carbon-containing fuels (propylene, acetylene, are a challenge to adjust so that they neither carbonize nor oxidize the workpiece as the flame is moved over it. --Chuck