Thanks a lot for your answers !

So I'll try to find a multiple-port tip.
Good idea to look on the side of jewellry/glass pearls makers; in Europe it seems they are the most common users of propane + concentrator (but I don't know how much this application is different of fillet brazing a bike, in term of heating, gas flow,..).

It's used in plumbing too, but not that much (a lot of mini cheap kits with super expensive disposable bottles, some conversions from oxy-acetylene). In fact, this process isn't well known here (just as CO2 MAG for steel).



Because of the pandemia the medical device maintenance companies are really busy, but I had a contact with one near to my location that could have some concentrators no longer usable for medical application to sell; I'm waiting for news and prices. The funny thing is that the seller itself use a concentrator for oxy/propane brazing.

I looked for a 2 stage regulator with 1-4 bars output, but it's not common at all in Europe (as oxy/prop is not used, and usual applications only require single stage or low pressure), just found this one in UK wit a limited output pressure. I'll continue to search, and maybe buy a single stage if I don't find better.

So for my current cargo, the lack of penetration of the fillet between and inside the tubes should make fillet not realy effective ?