HHO Gas Purity: Contaminants That Reduce Performance

What's in Raw HHO Gas?

Raw HHO from a generator is not pure H₂ and O₂. It typically contains:

• Water vapor: 10–30% by volume depending on temperature and gas flow rate
• Electrolyte mist (KOH droplets): Entrained by the rising gas stream
• Trace oxygen-containing compounds: From electrolyte decomposition

Water Vapor

Some water vapor is actually beneficial — it has a mild anti-knock effect on gasoline engines. However, excessive water vapor (from an overheating cell) displaces useful HHO gas and can cause rough idle or misfires. Keep cell temperature below 50°C to minimize vapor carryover.

Electrolyte Mist

KOH mist is the most harmful contaminant. It's alkaline, corrosive to aluminum intake components, and can foul oxygen sensors and mass airflow sensors. The bubbler eliminates virtually all electrolyte mist — this is why it's non-negotiable.

The Bubbler as Purifier

By bubbling HHO through a column of distilled water, you simultaneously scrub electrolyte mist and partially saturate the gas with clean water vapor. This is a better outcome than either raw HHO or zero water vapor — the clean moisture content benefits combustion slightly.

Activated Carbon Filtration

For extreme purity requirements (experimental engines or performance builds), adding an activated carbon stage after the bubbler removes additional organic contaminants from the gas stream. This is overkill for most automotive HHO applications but used in research setups.