Liquid oxygen, hazards

Also, beeause the boiling points of these eryogenie liquids are lower than that of oxygen, if exposed to air they ean eause oxygen to eondense preferentially, resulting in hazards similar to those of liquid oxygen. 

Hazards arising from the oxidation of organic compounds are greater when the reactants are volatile, or present as a dust or an aerosol. Liquid oxygen and various concentrated acids, e.g. nitric, sulphuric or perchloric acid, and chromic acid are strong oxidizing agents. The use of perchloric acid or perchlorates has resulted in numerous explosions their use should be avoided when possible (refer to Table 6.5). 

Accidental addition of liquid oxygen to vacuum jars containing acetone residues from trap-cooling use caused a violent explosion. Liquid nitrogen is less hazardous as a trap coolant, but only under controlled conditions. 

The detonation capacity of mixtures of acetylene and liquid oxygen is increased by the presence of organic material (oils) in the oxygen. Hazards of accumulation of oil in air-liquefaction and -fractionation plants are emphasised. 

The explosive properties of liquid methane-oxygen mixtures were determined [8], Dining investigation of an explosion in a portable air liquefaction-separation plant, hydrocarbon oil was found in a silica filtration bed [9], The mechanism of slow heterogeneous accumulation of hydrocarbons dissolved in trace amounts in liquid oxygen on the liquid evaporator surfaces is discussed. It was concluded that months of continuous evaporation would be required to attain explosion-hazardous levels in real evaporators [10],... 

Many common polymers, polymeric additives and lubricants oxidise so rapidly after impact in liquid oxygen that they are hazardous. Of those tested, only acrylonitrile-butadiene, poly(cyanoethylsiloxane), poly(dimethylsiloxane) and polystyrene exploded after impact of 6.8-95 J intensity (5-70 ft.lbf). All plasticisers (except dibutyl sebacate) and antioxidants examined were very reactive. A theoretical treatment of rates of energy absorption and transfer is included [1], Previously, many resins and lubricants had been examined similarly, and 35 were found acceptable in liquid oxygen systems [2],... 

Ozone is strongly endothermic (A(g) +142.2 kJ/mol, 2.96 kJ/g) and the pure solid or liquid materials are highly explosive. Evaporation of a solution of ozone in liquid oxygen causes ozone enrichment and ultimately explosion [1], Organic liquids and oxidisable materials dropped into liquid ozone will also cause explosion of the ozone [2], Ozone technology and hazards have been reviewed [3], a safe process to concentrate ozone by selective adsorption on silica gel at low... 

Oxidizers will nearly always be identified as such on their MSDSs or International Chemical Safety Cards. They may be identified as DOT/UN Hazard Class 5.1 materials for shipping purposes and labeled as oxidizers. However, some oxidizers are classified otherwise. Chlorine, for example, is DOT/UN Class 2.3 (gases toxic by inhalation) and labeled as POISON GAS for shipping purposes it may also be labeled as a corrosive material. Liquid oxygen is Class 2.2 (nonflammable nontoxic compressed gases) but should be labeled as NONFLAMMABLE GAS and OXIDIZER. 

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