Liquid oxygen reacts with many materials such as wood, leather and asphalt. It has a strong mechanical impact with these materials. Mechanic impact represents potential for ignition between two materials when they strike each other during an operation. The process involves generation of heat through transfer of kinetic energy and creation of strain energy due to transfer of the momentum of one materials mass to another material. For mechanical impact to occur, the masses of the material involved must be large and must strike each other during service. Mechanical impact is common in gases and liquid oxygen as well as porous hydrocarbons such as asphalt.
Properties of oxygen make this possible. Oxygen is the only gas that supports combustion of combustible materials. Oxygen reacts violently with organic component such as asphalt. Oxygen saturated environment such as liquid oxygen can have explosive reaction with asphalt (Meyer, 2010). Asphalt is organic since it contains hydrocarbons. Therefore, mechanical impact occurs when liquid oxygen and organic asphalt contained in asphalt pavement come in contact.
The mechanical impact is strongly influenced by mechanical heat energy, which is kinetic energy or molecular motion energy. Friction between surfaces also results in mechanical heat energy. Compressing gas into a liquid also result in heat energy. This is notable in diesel engines where ignition sparking is negated by heat of compression, which relies on heat production through compressing air and mixing it with petroleum. Exothermic reactions occur when kinetic energy is transformed into molecular motion leading to a violent explosion. It this kind of reaction that occurs when liquid oxygen spill on asphalt pavements. If explosions do not occur immediately dropping something such as a hammer in the area of spill triggers the explosion.
For these reason, it is always important to cordon off area of liquid oxygen spill, avoid walking on such surfaces s or dropping anything on them until they are cleaned. Liquid oxygen is frequently used by patients in hospital and at home. It is important for the users to be taught safety measure and how to handle spill especially when they have asphalt floors.
Meyer, E. (2010). Chemistry of hazardous materials (5th ed.). Upper Saddle River, NJ: Prentice Hall.