[Downwindtracker2]

In the early '70 I bought a Japanese Tanaka torch set.( I've since switched over to Air Liquide .) About then I bumped into a welder on a job site and he was using a Tanaka as well. I asked him what he thought of the torch, he complained about the mixing. What was he talking about ? I've used various company supplied torches since the "80s .

[Franz©]

99% probability he was making excuses for his lack of skill and ability to use the torch properly.
Oxy and Acet are delivered to the torch handle seperately and remain seperated until they pass the valves in the handle.
Generally in a modern torch they will remain seperate gas streams until they enter the torch tip where they mix into a single combined gas stream.
How mixing is accomplished can vary from simply marrying the gases in a chamber or helical swirling. Given the volume of gas passing through the tip in a very short time, my opinion is references to mixing are more salesman crap than fact.
There have been sales wars in the welding industry since I started back in the days when torch sets were damn expensive and very few existed in the homeowner environment. Mixing of gases in the 60s was a big selling feature with manufacturer A claiming a helical mixer in the handle was superior to mixing in the tip and the other guy pointing out his system was safer. A big part of the argument was a fire starting in the mixer when the torch popped back since check valves and blowback preventers didn't yet exist for torches.

As someone who has experienced a mixer fire in the handle of a torch I can and will tell you that handle gets hot fast, and you want to get the valves closed fast as you can.

With regard to Tanaks cutting torches, they are 3 tubes to the tip assembly indicating the mix of fuel and oxygen happens in the head just before the gas mix enters the tip itself. That design is fairly similar to Smith torches, and it works well although it lights differently from torches that mix in the handle. I'm not finding any exploded views of Tanaka welding or combination torches to see what they do in those.

Side note, Tanaka appears to make Oxy/propane heating torches that look like decent units, but I can't locate explodeds on those either.

[Franz©]

Picture of Tanaka mixing system
It appears to be a replaceable element of the torch head rather than machinedinto the head itself

[Downwindtracker2]

Thanks. That also would explain the big cutting torches I sometimes came across. Even gauges were optional , on one old set ,there were just numbers on the regulator. I don't remember the brand. One of my partners, we worked in pairs, once showed me how to adjust the pressures by fine tuning the flame. So I guess they weren't all that uncommon. The Tanaka set was medium duty combination , as is my Air Liquide. When the company switched to a HD combination sets I got the medium duty ones. At least, parts will be available forever, well past my life time.