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Combustion and Explosion Hazard

Aufbauskizze He-Lager Faubourg
Sketch He-Reservoir Faubourg

There are three hazards that can lead to fire and explosions: combustible gases, oxygen as fire promoter and ozone.

Combustible gases

  • methane,
  • LNG (liquefied natural gas) and
  • hydrogen.
In certain mixture ratios with air, explosions are possible [1].
A dangerous hydrogen-air mixture can form by condensation of air on liquid hydrogen.
 
Oxygen
 
Liquid or gaseous oxygen can:
  • strongly promote combustion processes,
  • reduce the ignition temperature,
  • accumulate in combustible materials (especially also in clothes),
  • which will burn from violent to explosion like when ignited.
  • The figure shows the result of a helium purifier explosion, which has been caused by the accumulation of liquid oxygen in an active charcoal adsorber. [15].
 
Hazards in oxygen systems
  • unsuitable materials
  • mechanical failures
  • impurities (remaining from the production or the machining e.g. oil and grease, flux, dirt, rust and welding residues)
Ozone
  • A safety risk is posed by the production of ozone in systems which contain oxygen and which are exposed to gamma or neutron radiation. An explosive amount of ozone can already be created from the oxygen impurities in a liquid nitrogen system if exposed to radiation [16].
N.B.: A danger not to be forgotten is the possibility of fires in the vicinity of cryogenic installations.