Liquid Oxygen

The objective of the research was to validate and qualify what has been traditionally taught as fact in first responder’s hazardous materials training regarding response precautions to and the likely behaviors of liquid oxygen (LOx) during a release. Subject matter experts disagreed that these precautions were well-founded in precedent or science. Findings showed that mechanical impact pressure did cause a reaction in LOx and asphalt under very specific, yet unrealistic, conditions. Conditions that are not likely to be encountered during an emergency response. No reactions were observed by combining LOx with common saturated and unsaturated hydrocarbons and alcohols. No reactions were observed driving fire apparatus over frost and through a LOx pool on asphalt. No reactions were observed by combining LOx and ordinary combustible materials. No reactions were observed when spark ignition was used as a source of ignition. Pilot ignition sources were introduced directly into a LOx pool on asphalt without a reaction. However, immediate, and violent reactions were observed when pilot ignition or arc ignition was used to initiate combustion when combustible materials and fuels were in an ultra-high gaseous or liquid oxygen environment. Without flaming or arc ignition sources, no reactions were observed. The elimination of ignition sources and standard precautions for cryogenic materials are fundamental to a safe emergency response to LOx.

Traditional LOx Response Precautions Tested in this Study:

Do not walk on or drop any tools on the LOx frozen asphalt because it may cause an explosion.
Always wait 30 minutes after the last frost is gone before stepping on the asphalt due to a potential explosive reaction.
Do not drive over the LOx frozen asphalt because the weight of the vehicle could cause a detonation.
Do not allow LOx to contact combustible materials, such as dried grass in the median or hydrocarbons such as diesel fuel, because it will ignite spontaneously resulting in a fast and intense fire.
Do not introduce sources of ignition such as a road flare directly into LOx spilled on asphalt because the asphalt will ignite causing an intense fire or an explosion.