Chemical Products, in Particular, Ammonia, Flux and Chemical Preparations for Welding; Materials for Cleaning, Drying or Separation of Gases; Industrial Gases, in Particular, Hydrogen, Acetylene, [ Methane, Butane, Propane, ] Ethylene, Propylene, Oxygen, Ozone, Nitrogen, Argon, Helium, Rare Gases, Carbon Dioxide, Gas Mixtures; Medical Gases, in Particular Oxygen, Nitrous Oxide [ and Cyclopropane; and Liquid Oxygen Explosives ]