wichita.edu
…gas-including compressed gas, liquefied gas, pressurized cryogenic gas, compressed gas in solution, asphyxiant gas and oxidizing gas. Flammable gas --- A gas that, at ambient temperature and pressure, forms a flammable mixture with air at a concentration of 13 percent by volume or less; or a gas that, at ambient temperature and pressure, forms a range of…
https://www.wichita.edu/services/environmental_health_and_safety/Safety/compressed_gas_safety.php