Steam hazards explosion

Hard rubber presents a fire hazard when reduced on steam-heated rolls (see subsection Organic Polymers ). Its dust is explosive [Twiss and McGowan, India Rtwber]., 107, 292 (1944)]. 

A normal enclosure is meant for a reasonably clean atmosphere and a relative humidity not more than 50% for LT and 95% for FIT indoor enclosures. Where the atmosphere is laden with fumes or steam, saline or oil vapours, heat and humidity, excessive dust and water or contaminated with explosive and fire hazardous gases, vapours or volatile liquids (Section 7.11) a special enclosure with a higher degree of protection is required as in lEC 60529 or lEC 60079-14. For non-hazardous areas, the enclosure can be generally one of those discussed in Tables 1. 10 and 1. 11, and when required can be provided with special treatment to the metallic surfaces. For hazardous areas, however, special enclosures will be essential as discussed in Section 7.11. 

Another simple hazard is a pressure vessel rupture due lo over pressure. A steam vessel rupture may scald vorkers and injure them viih shrapnel. Many people died in the last century from boiler explosions. The ves-... 

Inspection by independent persons or bodies for safety purposes goes back to the middle of the nineteenth century. At that time, the focus of concern was the explosion of steam boilers, and this hazard was most prevalent in the textile industry. Consequently, a group of public-spirited individuals formed the Manchester Steam Users Association for the Prevention of Boiler Explosion. This body carried out boiler examinations and later added insurance as an inducement to the plant owners. By the beginning of the twentieth century steam and gas engines and electrical machines had been added, followed by lifts, cranes and hoisting machines. 

Disposal of 2 1 of the solvent into a rusted iron sewer caused an explosion. Initiation of the solvent-air mixture by rust was suspected [1], A hot gauze falling from a tripod into a laboratory sink containing some carbon disulfide initiated two explosions [2], It is a very hazardous solvent because of its extreme volatility and flammability. The vapour or liquid has been known to ignite on contact with steam pipes, particularly if rusted [3], When a winchester of the solvent fell off a high shelf and broke behind a rusted steel cupboard, ignition occurred [4],... 

In liquid phase aerobic oxidation of p-xylene in acetic acid to terephthalic acid, it is important to eliminate the inherent hazards of this fuel-air mixture. Effects of temperature, pressure and presence of steam on the explosive limits of the mixture have been studied. 

Low (subatmospheric) pressures are not in general as hazardous as the other extreme operating conditions. But a hazard, which does exist in low pressure plant handling flammables, is the ingress of air with consequent formation of a flammable mixture. Also steam explosions may take place if a volatile material (e.g. water) is fed to a low pressure system which results to a consequent vapourization. 

Possible hazards introduced by variations in experimental techniques in Kjeldahl nitrogen determination were discussed [1]. Modem variations involving use of improved catalysts and hydrogen peroxide to increase reaction rates, and of automated methods, have considerably improved safety aspects [2], An anecdote is given of the classic technique when sodium hydroxide was to be added to the sulphuric acid digestion and was allowed to trickle down the wall of the flask. It layered over the sulphuric acid. Gentle mixing then provoked rapid reaction and a steam explosion [3],... 

Explosion Hazard of Organic Vapors, Reduction of. A process which comprises the treatment of wood with. hydrocarbon vapors at an elevated temp, after which compressed air is used to impregnate the wood with a preservative. Expln hazards are reduced by introducing steam at 10—20psi before applying the air. Steam is added in an amt equal to the partial pressure of die organic vapor in the closed space... 

Pitch. Pitch used to be stored in solid form at the tar distillery in open bays, from which it was removed by small explosive charges. Loading of the lump pitch by mechanical shovel created a dust hazard both at the tar installation and at the customers, where the lumps had to be ground before use. In the 1990s, pitch is stored in tanks heated by superheated steam or circulating hot-oil coils and transported in liquid form in insulated rail, road tankers, or ships. When transport as a hot liquid is not feasible, not acceptable by the customer, or for small amounts, the pitch is converted into a dust-free particulate form, ie, short rods termed pencils, pastilles, or flakes. 

Examples of common safe practices are pressure relief valves, vent systems, flare stacks, snuffing steam and fire water, escape hatches in explosive areas, dikes around tanks storing hazardous materials, turbine drives as spares for electrical motors in case of power failure, and others. Safety considerations are paramount in the layout of the plant, particularly isolation of especially hazardous operations and accessibility for corrective action when necessary. 

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