Oxy-acetylene kits are heavy and expensive; oxy-propane is rather cheaper, but doesn't get so hot.
But for the small scale user, having a cylinder of oxygen around can be burdensome, and propane/air doesn't get very hot - certainly not hot enough to weld.
A low-rate oxygen generator/concentrator
provides oxygen, but at too low a pressure for serious welding.
Thus, behold the BorgCo electrolytic/mechanical oxygen concentrator.
The device consists of a high pressure electrolysis cell containing water and an electrolyte. Applying a DC voltage derived from mains power pressurizes one half of the cell with hydrogen and the other with oxygen.
The pure oxygen is led away to the primary collector reservoir through a pressure regulator.
The hydrogen is tapped off, mixed with atmospheric air, and fed to a small 4-stroke single cylinder internal combustion engine, where it is burned. The mechanical energy drives an oil-free compressor which transfers oxygen from the initial oxygen collection reservoir into the main oxygen reservoir, and also drives an injector pump which pumps more distilled water into the electrolysis cell as required..
This system generates high pressure pure oxygen on demand, and recovers energy from the otherwise "waste" hydrogen stream.
No cryogenic separation/distillation of air is required; the equipment operates at ambient temperature.
Unlike PSA systems, the output pressure can be arbitrarily high, depending on the compressor and the integrity of the secondary reservoir.
Startup time from cold is short compared to other such systems.