Oxidant explosion hazards

SAFETY PROFILE Poison by ingestion. Moderately toxic by skin contact and inhalation. A skin irritant. A very dangerous fire hazard, when exposed to heat or flame. Can react with oxidizers. Explosion hazard is unknown. Keep away from heat and open flame. To fight fire, use foam, CO2, dry chemical. When heated to decomposition it emits toxic fumes of NOx. See also AMINES. 

PRUSSIC ACID (74-90-8) HCN Highly flammable liquid. Unless inhibited (usually with phosphoric acid), material may undergo rapid spontaneous explosion and fire (especially material stored more than 90 days). Above the boiling point, 80°F/27°C, the vapors form explosive mixtures with air [explosion limits in air (vol %) 5.6 to 40 flash point 0 F/-18°C autoignition temp 1000°F/538°C Fire Rating 4 (anhydrous)]. Elevated temperatures above 122°F/50 C or contact with even traces of alkalis, amines, or amides can cause explosive polymerization. Violent reaction on contact with oxidizers (explosion hazard), acetaldehyde, imidoester hydrochlorides. Solutions containing more than 2 to 5%... 

HAZARD RISK Red Fire hazard when exposed to heat or oxidizers explosion hazard may explode on impact decomposition emits toxic fumes of phosphorus oxides Whtie extreme fire hazard ignites spontaneously in moist air decomposition emits toxic fumes of phosphorus oxides NFPA Code Not available. 

Some of the ketones may react violently with strong oxidizers. Explosion hazards are discussed below for individual ketones. 

Precaution Highly flamm. very dangerous fire hazard exposed to heat or flame reacts vigorously with oxidizers explosion hazard in vaporform exposed to heat or flame explosive limits 1.5-8.2% mixts. with bromine trifluoride may explode... 

There are explosion hazards with phthahc anhydride, both as a dust or vapor in air and as a reactant. Table 11 presents explosion hazards resulting from phthahc anhydride dust or vapor (40,41). Preventative safeguards in handling sohd phthahc anhydride have been reported (15). Water, carbon dioxide, dry chemical, or foam may be used to extinguish the burning anhydride. Mixtures of phthahc anhydride with copper oxide, sodium nitrite, or nitric acid plus sulfuric acid above 80°C explode or react violently (39). 

Finely divided barium is susceptible to rapid, violent combination with atmospheric oxygen. Therefore, in powdered form it must be considered pyrophoric and very dangerous to handle in the presence of air or other oxidising gases. Barium powder must be stored under dry argon or helium to avoid the possibihty of violent explosions. Massive pieces of barium, however, oxidize relatively slowly and present no explosion hazard if kept dry. 

Bromates represent a potential fire and explosion hazard if heated, subjected to shock, or acidified. They should not be allowed to contact reactive organic matter, including paper and wood. Industrial quantities are packed in fiber dmms with polyethylene liners or in metal dmms. Laboratory quantities are supphed in glass bottles. For shipment, a yellow oxidizer label is required under DOT regulations. 

Explosibility and Fire Control. As in the case of many other reactive chemicals, the fire and explosion hazards of ethylene oxide are system-dependent. Each system should be evaluated for its particular hazards including start-up, shut-down, and failure modes. Storage of more than a threshold quantity of 5000 lb (- 2300 kg) of the material makes ethylene oxide subject to the provisions of OSHA 29 CER 1910 for "Highly Hazardous Chemicals." Table 15 summarizes relevant fire and explosion data for ethylene oxide, which are at standard temperature and pressure (STP) conditions except where otherwise noted. 

About two-thirds of the N2 produced industrially is supplied as a gas, mainly in pipes but also in cylinders under pressure. The remaining one-third is supplied as liquid N2 since this is also a very convenient source of the dry gas. The main use is as an inert atmosphere in the iron and steel industry and in many other metallurgical and chemical processes where the presence of air would involve fire or explosion hazards or unacceptable oxidation of products. Thus, it is extensively used as a purge in petrochemical reactors and other chemical equipment, as an inert diluent for chemicals, and in the float glass process to prevent oxidation of the molten tin (p. 370). It is also used as a blanketing gas in the electronics industry, in the packaging of processed foods and pharmaceuticals, and to pressurize electric cables, telephone wires, and inflatable rubber tyres, etc. 

The total consumption type of burner consists of three concentric tubes as shown in Fig. 21.5. The sample solution is carried by a fine capillary tube A directly into the flame. The fuel gas and the oxidant gas are carried along separate tubes so that they only mix at the tip of the burner. Since all the liquid sample which is aspirated by the capillary tube reaches the flame, it would appear that this type of burner should be more efficient that the pre-mix type of burner. However, the total consumption burner gives a flame of relatively short path length, and hence such burners are predominantly used for flame emission studies. This type of burner has the advantages that (1) it is simple to manufacture, (2) it allows a totally representative sample to reach the flame, and (3) it is free from explosion hazards arising from unbumt gas mixtures. Its disadvantages are that (1) the aspiration rate varies with different solvents, and (2) there is a tendency for incrustations to form at the tip of the burner which can lead to variations in the signal recorded. 

Fire and Explosion Hazard. Dangerous, as K nitrate is both a fire and expln hazard. As a strong oxidizer it can give up its oxygen to other materials to produce a vigorous reaction which may result in detonation. Toxic fumes are emitted on decompn. It is sensitive to shock, can be very easily detonated, and when mixed with flammable materials becomes very sensitive (Refs 6 10)... 

Ethylene oxide gas is highly explosive in mixtures of >3.6% vN in air, in order to reduce this explosion hazard it is usually supplied for sterilization purposes as a 10% mix with carbon dioxide, or as an 8.6% mixture with HFC 124 (2 chloro-1,1,1,2 tetrafluoroethane) which has replaced fluorinated hydroearbons (freons). Alternatively, pure ethylene oxide gas can be used at below atmospheric pressure in sterihzer chambers from which all air has been removed. 

Finely divided aluminium powder or dust forms highly explosive dispersions in air [1], and all aspects of prevention of aluminium dust explosions are covered in 2 recent US National Fire Codes [2], The effects on ignition properties of impurities introduced by recycled metal used to prepare dust were studied [3], Pyrophoricity is eliminated by surface coating aluminium powder with polystyrene [4], Explosion hazards involved in arc and flame spraying of the powder are analysed and discussed [5], and the effect of surface oxide layers on flammability was studied [6], The causes of a severe explosion in 1983 in a plant producing fine aluminium powder are analysed, and improvements in safety practices discussed... 

In the analysis of diethylzinc, a 1 ml sample is cooled to — 196°C and treated with 2 ml of ethanol to give the ethoxide. During subsequent conversion to zinc nitrate (prior to pyrolysis to the oxide) by treatment with 3 ml of 30% nitric acid, cooling must be continued to avoid an explosion hazard. 

The finely powdered anti-oxidant is a significant dust explosion hazard. 

The explosion hazard associated with the usual laboratory preparation from white phosphorus and alkali may be avoided by an alternative method involving oxidation of phosphine with an aqueous iodine solution [1], The commercial 50% solution reacts violently with oxidants. On heating, it decomposes rapidly above 100°C evolving phosphine, which is liable to explode with air. It is recommended it... 

The earlier references, which state that this powerful oxidant is stable when pure, but explosive when formed as a layer on metallic potassium [1,2], are not wholly correct [3], because the superoxide is manufactured uneventfully by spraying the molten metal into air to effect oxidation [4], Previous incidents appear to have involved the explosive oxidation of unsuspected traces of mineral oil or solvents [3]. However, mixtures of the superoxide with liquid or solid potassium-sodimn alloys will ignite spontaneously after an induction period of 18 min, but combustion while violent is not explosive [3], The additional presence of water (which reduces the induction period) or hydrocarbon contaminant did produce explosion hazards under various circumstances [5], Contact of liquid potassium with the superoxide gives no obvious reaction below 117°C and a controlled reaction between 117 and 177°C, but an explosive reaction occurs above 177°C. Heating at 100°C/min from IT caused explosion at 208°C [6],... 

In the third step, the chemical structure is used to determine if the substance is compatible with materials which are common to the process unit, such as air, water, oxidizers and combustibles, acids, alkalies, catalysts, trace metals, and process utilities (see Section 2.2.4). Even if the substance is considered to be a non-explosion hazard (both nonenergetic and compatible with the... 

UNUSUAL FIRE AND EXPLOSION HAZARDS Never mix or store acids, oxidizing agents, Super Tropical Bleach (STB) or High Test Hypochlorite (HTH) together with DS2 fire or explosion may result. 

U.S. Environmental Protection Agency (USEPA), 2000. Case Study Waste Fuel/Oxidizer Reaction Hazards, Prevention of Reactive Chemical Explosions, EPA 550-F00-001, Office of Solid Waste and Emergency Response, April 2000. 

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