How hydrogen bath machines work

Pure water in the source reservoir is drawn across a PEM (Proton Exchange Membrane) or SPE (Solid Polymer Electrolyte) stack. A DC current splits each water molecule into 2H⁺ + ½O₂ at the anode; protons cross the membrane and recombine with electrons on the cathode side as H₂. Only the hydrogen stream is routed onward.

Output is governed by membrane plate area, current density and cell count. A bath chassis uses a much larger total plate area than an inhaler to produce the gas volume a tub needs within a sensible saturation window.

The hydrogen stream is delivered into the tub through a hose terminating in a dissolution head submerged below the water surface. The head breaks the gas into fine bubbles and forces them upward through the water column.

Two physical variables determine how much of that gas dissolves rather than surfacing: bubble size and water-contact time. Smaller bubbles (nanobubble / microbubble scale) have a much larger surface-area-to-volume ratio, and a longer column gives them more time to dissolve before reaching the surface.

Some systems supplement the head with a separate hydrogenation chamber that pre-saturates the water before injection — this raises the achievable dissolved concentration but adds size and cost.

Once a tub reaches working concentration, dissolved H₂ continues to escape at the surface at a rate set by water temperature, surface area and movement. The machine has to keep producing H₂ through the session to replenish those losses.

This is why the relevant spec is sustained ppb across a 20–30 minute window — not peak ppb, not visible bubble volume.

An inhaler is engineered to deliver ~1 L/min of pure H₂ through a small port at the user's nose. Plumbed into a tub, that gas bubbles out at the surface long before dissolving. The plate area is too small to ever reach a meaningful dissolved concentration in 150–200 L of water, and the dissolution head — designed for a cannula — produces large bubbles that surface immediately.