Ozone precautions

Dry cleaning - Several solvents exist to replace the ozone-depleting solvents that have traditionally been used by the dry cleaning industry. Perchloroethylene has been used for more than three decades. Petroleum solvents, while flammable, can be safely used when appropriate safety precautions are taken. They include white spirit, Stoddard solvent, hydrocarbon solvents, isoparaffins, and n-paraffin. A... 

Liq ozone in concns greater than 30% by wt is extremely unstable, and may expld on contact with even minute traces of organic matter. Not only all precautions for handling liq oxygen, but also extra precautions for a sensitive expl must be observed (Ref 4, p 430)... 

Over-pressurization, See also Pressure rupture, 46 Ozone, 16 hazards, 303 physical properties, 303 physiological properties, 304 precautions, 304... 

All of the theoretically possible high-energy (and potentially hazardous) oxidant-fuel systems have been considered for use, and many have been evaluated, in rocket propulsion systems (with apparently the sole exception of the most potent combination, liquid ozone-liquid acetylene). Some of the materials which have been examined are listed below, and it is apparent that any preparative reactions deliberately involving oxidant-fuel pairs must be conducted under controlled conditions with appropriate precautions to limit the rate of energy release. 

Hydroxylation of t-carbon atoms. Detailed directions including necessary precautions for dry ozonation have been published. Seven examples for preparation of tertiary alcohols arc included (yields 72-90%). 

With the addition of hydrogen peroxide to UV radiation, the elimination rate of pollutants can be increased. Hydrogen peroxide is cheaper than ozone production, and the application is less complicated and requires less safety precautions than the more toxic ozone. All this allows hydrogen peroxide/UV radiation to be easily included in a treatment scheme. It has its drawbacks though. 

Cryogenic collection of true hydrocarbons as well as some oxygenated hydrocarbons works well if precautions are taken to remove ozone. 

High voltage equipment (e.g. for use in electrophoresis, or in the generation of ozone) requires special precautions. Ideally, such apparatus should be isolated within an enclosure equipped with an interlocking device so that access is possible only when the current is switched off. 

The addition of a gas to a reaction mixture (commonly the hydrogen halides, fluorine, chlorine, phosgene, boron trifluoride, carbon dioxide, ammonia, gaseous unsaturated hydrocarbons, ethylene oxide) requires the provision of safety precautions which may not be immediately apparent. Some of these gases may be generated in situ (e.g. diborane in hydroboration reactions), some may be commercially available in cylinders, and some may be generated by chemical or other means (e.g. carbon dioxide, ozone). An individual description of the convenient sources of these gases will be found under Section 4.2. 

These studies indicate that liquid ozone-fluorine mixtures are homogeneous and do not form a two-phase region as does the ozone-oxygen system. Mixtures of 30% ozone in fluorine require very few handling precautions over those observed with 100% liquid fluorine. 

Further safety precautions for the operation of photochemical equipment include protection against electrocution risks and efficient ventilation to prevent ozone exposure. Certain lamps may produce significant amounts of ozone de-... 

Moreover by recovering all of the ozone formed and taking all the necessary precautions when evaporating liquid oxygen and then liquid ozone, approximately 3 grams of ozone per kilowatt-hour were obtained, which constitutes a noticeable improvement over experiments with gaseous oxygen. 

Because of the unstable nature of ozone, the usual techniques for determination of physical properties can rarely be applied. Contact with many materials generally used in experimental work, such as rubber tubing, organic stopcock grease, and mercury, must be avoided. The quantity of pure liquid ozone must be kept small in the interests of safety. Even 1 ml. of undiluted liquid ozone can cause a disastrous explosion unless suitable precautions are taken to protect the experimenter. 

In spite of all precautions, explosions may occur. Pure liquid ozone at temperatures near its normal boiling point is particularly dangerous. At this temperature the slightest jar or vibration may cause an explosion. The most disastrous explosion, however, occurred when about 1 ml. of pure liquid ozone was in a glass tube immersed in 2 liters of liquid nitrogen. At this temperature liquid ozone had been thought fairly safe. 

The decomposition of ozone at ordinary temperatures complicates the preparation of mixtures of known composition. At liquid air temperatures, thermal decomposition is negligible and, with precautions to avoid sensitized decomposition, stable liquid mixtures may be prepared. The density of liquid ozone has been reported (3) with a margin of error of 0.25%, permitting volumetric preparation of mixtures with comparable accuracy. 

The tests described above showed that any of these concentrations of ozone could be handled safely with suitable precautions. 

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