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BASICS OF SAFE LIFE
Emergencies at chemically hazardous economic facilities and when using chemical weapons. Basics of safe life
Directory / Basics of safe life OE of the chemical and petrochemical industry are characterized by a huge number of a wide variety of fire and explosive processes, and the substances used with high toxicity violate the usual composition of atmospheric air. Air plays a vital role in the metabolism of a living organism. A person cannot live without air for more than a few minutes. Air is a mixture of gases that varies with height from the Earth's surface (Table 4.1). Table 4.1. Percentage composition of atmospheric air (main components)
In addition, the composition of the air includes carbon dioxide, carbon monoxide, inert gases, a large number of substances of natural and anthropogenic origin (water vapor, dust, chemical and organic substances in the form of vapor or aerosols). The qualitative and quantitative composition of the atmosphere is constantly changing, which can become a prerequisite for the development of emergencies. Aerosols can be in solid or liquid dispersed phase. Particle sizes of impurities can constantly change, move and settle on a variety of surfaces. Aerosols often adsorb gaseous and vaporous chemicals, and particulate matter can be dissolved in aerosol droplets. Air is an oxidizing environment. For example, if the oxygen content in the atmosphere were not 21, but 25%, then this would lead to a fire in a tree even in heavy rain and all plants on Earth would have been destroyed long ago! And with a 10% oxygen content in the atmosphere, even completely dry firewood could not burn. Foreign matter in the atmosphere reduces the access of ultraviolet rays and forms nuclei for condensation of water vapor or freezing of atmospheric moisture, which leads to the formation of haze, shroud, fog or rain in the area. Many chemical processes proceed at high temperatures and pressures, using a large amount of explosive and flammable substances. Even minor changes in the parameters of the technological process can lead to a sharp change in the rate of reactions or the development of side processes - followed by an explosion in equipment, communications or premises. Therefore, the strict implementation of safety measures, compliance with the technological process and operating modes, as well as the competent operation of the equipment are of particular importance. Automatic protection systems used in the chemical and petrochemical industries are designed for:
When designing equipment, errors are possible in the arrangement of thermal compensators, supports and fixtures, in the placement of pipelines on overpasses, and the properties of the transported gases are not taken into account. Thus, the danger of an explosion of acetylene directly depends on the diameter and length of the gas pipeline: an increase in the size of acetylene pipelines can lead to an explosion. If the gas velocity in pipelines with a flare installation turns out to be underestimated (or a system for purging equipment with inert gas and igniting combustible gas when it is suddenly discharged into a flare is not provided), then gas contamination of the air pool will occur and accidents are possible. The danger of hazardous chemicals (SDYAV) in terms of contamination of the surface layer of the atmosphere is determined by their physical and chemical properties, as well as their ability to go into a "damaging state", that is, to create a concentration that affects people, or to reduce the oxygen content in the air below an acceptable level. All AHOV (SDYAV) can be divided into three groups, based on their boiling point at atmospheric pressure, critical temperature and ambient temperature; state of aggregation AHOV (SDYAV); storage temperature and operating pressure in the vessel. The 1st group includes AHOV (SDYAV) with a boiling point below -40°C. When these substances are released, only a primary gas cloud is formed with the likelihood of an explosion and fire (hydrogen, methane, carbon monoxide), and the oxygen content in the air is also sharply reduced - especially in enclosed spaces (liquid nitrogen). When a single container is destroyed, the duration of the gas cloud does not exceed a minute. The 2nd group consists of AHOV (SDYAV) with a boiling point from -40°C to +40°C and a critical temperature above the ambient temperature. To bring such SDYAV into a liquid state, they must be compressed. Such SDYAV are stored refrigerated or under pressure at normal temperature (chlorine, ammonia, ethylene oxide). The release of such SDYAV usually gives a primary and secondary cloud of contaminated air (03B). The nature of infection depends on the ratio between the boiling points of SDYAV and the air temperature. So, butane (twhale\u0d 1 ° C) in hot weather will be similar in action to SDYAV of the 3st group, that is, only the primary cloud will appear, and in cold weather - SDYAV of the 03rd group. But if the boiling point of such a substance is lower than the air temperature, then when the tank is destroyed and SDYAV is released, a significant part of it may turn out to be in the primary XNUMXB, since the liquid in the tank boils at a pressure much less than atmospheric. At the same time, noticeable hypothermia and moisture condensation can be observed at the accident site. 3rd group - AHOV (SDYAV) with a boiling point above 40 ° C, that is, all SDYAV that are at atmospheric pressure in a liquid state. When they are poured out, the area is contaminated with the danger of subsequent contamination of groundwater. The liquid evaporates from the soil surface for a long time, that is, the formation of secondary 03B is possible, which expands the affected area. The most dangerous AHOV (SDYAV) of the 3rd group, if they are stored at elevated temperatures and pressures (benzene, toluene). The classification of harmful substances is shown in fig. 4.1.
Rice. 4.1. Classification of harmful substances Some of the most common AHOVChlorine - poisonous gas, which is almost 2,5 times heavier than air. Often used in pure form or in combination with other components. At a temperature of about 20 ° C and atmospheric pressure, chlorine is in a gaseous state in the form of a greenish-yellow gas with an unpleasant, pungent odor. It vigorously reacts with all living organisms, destroying them. Liquid chlorine is a mobile oily liquid, which at normal temperature and pressure has a dark greenish-yellow color with an orange tint, its specific gravity is 1,427 g/cm3. At -102°C and below, chlorine hardens and takes the form of small dark orange crystals with a specific gravity of 2,147 g/cm3. Liquid chlorine is poorly soluble in water, and chlorination of water at the disinfection facilities of the water utility is carried out only with the help of gaseous chlorine. The production of gaseous chlorine (hydrogen and alkali) is based on the electrolysis of table salt. This is a complex complex: brine preparation, its purification, evaporation, electrolysis, cooling, gas pumping. A dry mixture of chlorine with air explodes at a chlorine content of 3,5 ... 97%, that is, mixtures containing less than 3,5% chlorine are non-explosive. Particularly dangerous in terms of the strength of the explosion are mixtures in which chlorine and hydrogen are in a stoichiometric ratio (1: 1). Such mixtures explode with the greatest force, and the explosion is accompanied by a powerful sonic boom and flame. The initiator of an explosion of a hydrogen chloride mixture (except for an open flame) can be an electric spark, a heated body, direct sunlight in the presence of contacting substances (charcoal, iron and iron oxides). Wet chlorine causes severe corrosion (this is hydrochloric acid), which leads to the destruction of tanks, pipelines, fittings and equipment. An emergency situation in the workshop can occur when the water supply, electric current is suddenly turned off, an explosive mixture is formed, chlorine (gas) enters the production room, overpressure is created in the hydrogen collector during electrolysis, in case of fire. In such situations, appropriate light or sound alarms should be triggered, and hydrogen compressors should automatically stop. Railway tanks, containers, barrels, cylinders should be filled only to the permissible weight - with careful control of the mass of empty and filled containers, since liquid chlorine increases in volume by almost 0,2% when heated on GS, and with an increase in pressure for every 100 kPa its volume decreases by 0,012%, that is, in a vessel filled with liquid chlorine, an increase in temperature by 1 ° C leads to an increase in pressure by 1500 ... 2000 kPa. The rate of filling vessels with liquid chlorine is set at the rate of 1,25 kg of chlorine per 1 liter of capacity. On metals, except for tin and aluminum, dry chlorine has almost no effect, and in conditions of moisture it exposes them to severe corrosion. At a concentration of chlorine in the air of 0,1-0,2 mg / l, a person develops poisoning, a choking cough, headache, pain in the eyes, damage to the lungs, irritation of the mucous membranes and skin. The victim must be immediately taken out to fresh air (only in a horizontal position, because due to pulmonary edema, any load on them provokes an aggravation of the lesion), warm, let it breathe with vapors of alcohol, oxygen, wash the skin and mucous membranes with a 2% soda solution in within 15 min. Ammonia - colorless gas with a pungent, suffocating odor of ammonia. A mixture of ammonia vapor with air at a volume content of ammonia from 15 to 28% (107 ... 200 mg / l) is explosive. The explosion pressure of an ammonia-air mixture can reach 0,45 MPa with a volume content of ammonia in the air above 11% (78,5 mg/l). In the presence of an open flame, the combustion of ammonia begins. At a pressure of 1013 GPa (760 mm Hg), its boiling point is -33,3°C, solidification -77,9°C, ignition 630°C. The content of ammonia in the air:
Ammonia causes damage to the body, especially the respiratory tract. Signs of gas action: runny nose, cough, shortness of breath, pain in the eyes, watery eyes. When liquid ammonia comes into contact with the skin, frostbite occurs, burns of the 2nd degree are possible. The victim should be transported in a horizontal position. Hydrocyanic acid (HCN) and its salts (cyanides) are produced by the chemical industry in large quantities. This acid is widely used in the production of plastics and artificial fibers, in electroforming, and in the extraction of gold from gold-bearing ores. Under normal conditions, hydrocyanic acid is a colorless, transparent, volatile, flammable liquid with a bitter almond odor. Melts at -14°C, boils at +25,6°C. The flash point is -17°C. Vapors of hydrocyanic acid with air form explosive mixtures at 5,6 ... 40% (by volume). Hydrocyanic acid is one of the strongest poisons, leading to paralysis of the nervous system. Penetrates the body through the gastrointestinal tract, blood, respiratory organs, and with a high concentration of its vapors - through the skin. It is poorly adsorbed by activated carbon, that is, for protection it is necessary to use industrial gas masks of grades B, BKF, which have special chemical absorbers. The poisoning effect of hydrocyanic acid depends on the amount and speed of its entry into the body: 0,02 ... 0,04 mg / l are painlessly tolerated for 6 hours; 0,12 ... 0,15 mg / l are life-threatening after 30-60 minutes; concentrations of 1 mg/l and above lead to almost instantaneous death. The damaging effect of hydrocyanic acid is due to the blocking of iron-containing cell enzymes that regulate oxygen uptake. It is completely miscible with water and solvents. Sulfur dioxide (sulfur dioxide, sulfur dioxide) is obtained by burning sulfur in air. It is a colorless gas with a pungent odor. At normal pressure, it passes into a liquid state at a temperature of -75 ° C, 2,2 times heavier than air. It dissolves well in water (under normal conditions, up to 40 volumes of gas dissolve in one volume of water), forming sulfurous acid. It is used in the production of sulfuric acid and its salts, in paper and textile production, in fruit canning, and for disinfection of premises. Liquid sulfur dioxide is used as a refrigerant or solvent. Average daily MPC of sulfur dioxide in the atmosphere of a settlement 0,05 mg/m3, and in the working room - 10 mg/m3. Even a small concentration of it creates an unpleasant taste in the mouth and irritates the mucous membranes, a higher concentration irritates the skin, causes coughing, eye pain, burning, lacrimation, and burns are possible. With a significant excess of the MPC, hoarseness, shortness of breath appear, the person loses consciousness. Possible fatal outcome. First aid: take the victim to fresh air, rinse the skin and mucous membranes with water or a 2% solution of baking soda, and rinse the eyes with running water for at least 15 minutes. Air contamination with a damaging concentration of this gas can occur in the event of an industrial accident at a chemically hazardous OE, leakage during storage or transportation. The danger zone must be isolated, outsiders must be removed, work only in protective equipment. Depending on the concentration of sulfur dioxide (in MPC), industrial gas masks of grade B, E, BKF or insulating gas masks (if the concentration is unknown) are used. Spilled liquid must be protected with an earthen rampart, preventing water from entering it (when extinguishing a fire!). Provide isolation of liquid sulfur dioxide from reservoirs, water supply and sewerage systems. Heptyl (hydrazine, diamide, unsymmetrical dimethylhydrazine) - a liquid fuming in air with an unpleasant odor. Melts at +1,5°C. Soluble in water, alcohols, amines, insoluble in hydrocarbons. Heptyl is hygroscopic, forms explosive mixtures with air, and upon contact with asbestos, coal, iron, is capable of self-ignition. Heavier than air. Decomposes in the presence of a catalyst or when heated above 300°C. Refers to extremely hazardous substances (hazard class 1). MPC in the air of the working area 0,1 mg/m3. It is most commonly used as a combustible propellant component. When spilled, it penetrates deep into the soil (more than 1 m) and remains there unchanged for up to 20 years. It enters the human body through the skin, mucous membranes or by inhalation (in the form of steam). Threshold toxodose 14, short-term permissible concentration 000 mg/m3, life-threatening - 100 mg/m3, lethal - 400 mg/m3. Causes temporary blindness (up to a week), burns on the skin, when absorbed into the blood leads to disorders in the central nervous and cardiovascular systems, blood (destruction of red blood cells and anemia). Signs of poisoning: agitation, muscle weakness, convulsions, paralysis, decreased heart rate, acute vascular insufficiency, nausea, vomiting, diarrhea, possible damage to the kidneys and liver, coma. When leaving a coma, psychosis with delusions, auditory and visual hallucinations are possible for several days. The presence of heptyl in the air is determined by a photometric method, and in case of emergency - using indicator tubes for heptyl. Nitric acid has a density of 1,502 g/cm3. Its vapors are 2,2 times heavier than air. Miscible with water in all respects with the release of heat. It is very hygroscopic, strongly "smokes" in air, acts on all metals except noble ones and aluminum. Ignites organic materials, releasing nitrogen oxides, which have high damaging properties. When nitric acid enters turpentine or alcohol, an explosion occurs. Toxic doses: damaging 1,5 mg/l, lethal 7,8 mg/l. Chemically dangerous object (XOO) is called OE, in the event of an accident or destruction of which mass damage to people, animals, and plants can occur. The regulatory documents of the government established a list of hazardous chemical products (AHOV) and determined the standards for their storage at the ONX. Depending on this, a sanitary protection zone is established around the HOO. Its value for the 1st class HOO is 1 km, for the 2nd class HOO - 0,5 km, the 3rd class - 0,3 km, the 4th class - 100 m, the 5th class - 50 m. The administration of the HOO must ensure the safety of the population in the area of its deployment, and, if necessary, take additional measures: notification, provision of protective equipment, evacuation of the population of the area. There should be reserve tanks for pumping from emergency or collecting spilled hazardous chemicals. Statistics show that the average annual concentrations of highly hazardous substances in the atmosphere do not decrease from year to year and often exceed the maximum permissible values by several times (Table 4.2). Table 4.2. Exceeding the MPC (number of times) of harmful substances in the atmosphere of some cities
At the facilities, AHOV are stored in containers: tanks, reservoirs, tanks, tanks, barrels under pressure or in liquid form. Their production, storage and transportation are strictly regulated. According to the effect on the body, most AHOVs are substances of general poisonous or asphyxiating action. Chemically hazardous OE and the territory (region, city, district) are classified as the 1st degree of danger for infection if more than 75 thousand people fall into the zone of its action (or for the region more than 50% of the population); to the 2nd degree - respectively, more than 40 thousand people (more than 30% of the population); to the 3rd degree - at least 40 thousand people (more than 10% of the population); The 4th degree of danger is established only for CSOs, the territory of infection of which does not go beyond its sanitary protection zone. An analysis of accidents that occurred during the operation of gas pipelines shows that more than 40% of such accidents are caused by violations in the design of gas pipelines and safety rules during installation and repair work. There are quite frequent cases of destruction of pipelines with ammonia, chlorine during the movement of oversized cargo on the territory of the OE. Pipeline failures are caused by untimely and poor-quality control over their condition during the operation period - the appearance of cracks, fistulas. If there is water in the transported gases, then ice plugs can form in the gas pipeline during untimely purges. Incorrect actions of personnel during pipeline defrosting often lead to accidents. As an example of the development of an accident at the HOO, one can cite the incident at the Production Association "CJSC" (Ionova, Lithuania). Here, on March 20.3.92, 7000, a tank with 7 tons of ammonia collapsed. A fire started, air pollution turned out to be significant, 50 people died, 30 were injured. In total, about XNUMX thousand people were evacuated from the danger zone. A significant concentration of nitric oxide (a strong poison that affects the blood) arose in the atmosphere. As a result of an accident at a chemical protection facility, a chemical attack site (OCCP) often occurs, characterized by the length and width of the zone of direct contamination. In turn, the length of the AHOV distribution zone can be divided into a zone of lethal concentration and a zone of damaging concentration. The size of the OCHP depends on the amount of hazardous chemicals in the "release", their type, the nature of the release, weather conditions, terrain, the nature of buildings, and vegetation. Depending on the size and danger of the POC, the civil defense and emergency services organize rescue operations and liquidation of the consequences of the accident, ensuring work package:
The success of rescue operations largely depends on the timeliness, reliability and completeness of data on the situation, the quality of forecasting by the working body of the Civil Defense and Emergency Situations, the efficiency of the observation network and laboratory control. The forces and means of the Civil Defense and Emergency Situations must be in constant readiness for action and have the necessary amount of personal and collective protective equipment. To prevent the occurrence of accidents at chemical facilities, it is necessary to:
HOO should be located as far as possible from residential areas. At present, there is an acute problem of what was previously considered harmless dioxin. It turned out to be the most dangerous of the poisons discovered by man: more toxic than cyanides, curare, military agents. Dioxin is not one specific substance, but a whole class of chemical compounds that are usually formed in an oxygen environment from benzene rings in the presence of chlorine or bromine, especially at high temperatures. In the 50s, scientists suspected that dioxin was the culprit for many diseases, and many of them proved this by the loss of their health. Dioxins are supplied to the environment by enterprises for the purification of graphite, for the manufacture of herbicides, gasoline, as well as pulp and paper, electrolysis plants. Dioxins also occur during the burning of garbage, the disposal of chlorine-containing waste, and during fires at power plants. The effect of this poison on a person - at significant concentrations - is terrible: many die immediately, and the survivors develop non-healing ulcers on the body, mental disorders, and malignant tumors. Even small doses of dioxin lead to the birth of deformed children, a catastrophic drop in immunity. These are very stable compounds (withstand heating up to 1200°C, have a half-life of up to 20 years). Dioxin accumulates in the liver, thymus gland, hematopoietic organs, suppressing the immune system, causing mutations, malignant tumors. The content of dioxins in foods, liquids and air must be limited. For drinking water, the concentration of dioxins should not exceed 20 pg/l (lpg = 10-12г). It is possible to detect such a quantity of a substance only using very sensitive and extremely expensive instruments. The lethal dose of dioxin for humans does not exceed 1/3 aspirin tablets. In 1995, phenols got into the Ufa water supply system. Their interaction with chlorinated water led to the formation of dioxins and mass poisoning of the population. In Russia, 6 laboratories conducting dioxin analyzes have been certified. Dioxins were the main damaging element of the US chemical warfare in Vietnam, over the territory of which over 45 million liters of dioxin-forming defoliant were sprayed. This is the reason for the huge number of victims and victims of the use of "non-dangerous" defoliants. Many of the victims are still paying for this with the health of their own and their children. More than 60 former US servicemen sought medical help with complaints of a sharp deterioration in health, the appearance of a "chlorine rash" and malignant formations on the skin, severe headaches, diseases of the gastrointestinal tract, liver, and impaired coordination of movements. Health professionals confirm the connection of these diseases with exposure to chemicals. According to the US, 538 former soldiers who had contact with dioxin had 77 crippled children (deaf, blind), but these consequences are especially deplorable for Vietnam. The combined effect of dioxin and radiation leads to a sharp increase in negative consequences. So, the total effect of 10 MPC of radiation exposure and 10 MPC of dioxin is equivalent to the action of 40 ... 60 MPC. Even your own apartment does not save you from polluted air from the street. The measurements showed that indoor air pollution, where a person spends up to 80% of the time, is 1,8...4 times higher than outdoors. There are more than 100 volatile chemicals and metals in the form of aerosols (lead, cadmium, mercury, zinc). The reason for this is the "chemicalization" of construction and the uncontrolled addition of harmful substances and industrial waste to building materials (Table 4.3). Table 4.3. Chemicals released from finishing materials and furniture
Chemical weapons are different OVs. Chemical weapons also include special substances intended for the destruction of plants (herbicides, defoliants). There are several classifications of OV 1. According to the behavior of the OV on the ground during combat use:
2. According to the danger to human health and life:
3. The classification dividing agents into groups depending on their toxic effect has received the greatest use:
During the passage of the ER, particles of OM are deposited on the terrain, equipment, buildings, clothing, and people. As a result of human contact with contaminated surfaces, as well as the use of contaminated food and water, people are affected. A quantitative characteristic of the degree of contamination of surfaces is the density of contamination (g/m2), that is, the amount of OM per unit area of the contaminated surface. A quantitative characteristic of contaminated air and water is the concentration of OM - the amount of OM contained in a unit volume (g / m3). Toxicity is the ability of an agent to have a damaging effect on a living organism. Determined by the toxic dose. Toksodoz - a quantitative characteristic of the toxicity of agents, corresponding to a certain effect of damage. If the average concentration of RH in the air is measured in g/m3, then a person through the respiratory system in t minutes will receive a toxodose in g * min / m3. The effect of damage through the skin is determined in mg / person, that is, the toxodose is determined by the mass of liquid OM (mg) that has entered the human skin (Table 4.4). To characterize the toxicity of agents when exposed to humans through the respiratory organs, the average lethal toxodose is often used, at which death is observed in 50% of the victims, which is indicated by the combination LD50 (L - from lat. lethal, that is, fatal) (Table 4.5). As a result of the use of chemical weapons, a difficult situation may result with the formation of an OCHP (territory exposed to the action of agents, where people and animals can be injured). OChHP can be divided into several zones (Fig. 4.2). Table 4.4. Toxicological characteristics of agents
Table 4.5. Characteristics of the main toxic substances
Rice. 4.2. View of the focus of chemical damage during the release of SDYAV The zone of direct OS spill (application area) is characterized by the length and width of the OS application area. The zone of distribution of contaminated air is characterized by the depth of distribution in the direction of the wind with the preservation of lethal concentrations (Gcm) and damaging concentrations (Gpores). Outside the latter, people can be without PPE. The shape of the zones of distribution of contaminated air is determined by the wind speed and can be in the form of a circle, semicircle or sector of a certain angular size. Meteorological conditions, terrain, building density and other factors have a great influence on the formation of OCHP. I provide high temperature of the soil and the lower layers of air! rapid evaporation of AHOV (OV) from contaminated surfaces, and the wind disperses these vapors, reducing their concentration. In winter conditions, the evaporation of OM is insignificant, and the contamination of the area will be long-term. In this case, it is necessary to take into account the degree of vertical stability of the surface layers of the atmosphere. Inversion and isotherm ensure the preservation of a high concentration of OM in the surface air layer and the spread of a cloud of contaminated air over considerable distances. Convection causes the dissipation of the contaminated cloud, i.e. a decrease in the concentration of OB vapors. The most favorable for the use of OM is dry, quiet, cool weather: OM quickly settles on the surface of objects and retains a high concentration for a long time. To protect against RH, it is necessary to seal the premises and shelters, as well as to create air overpressure in them. The degree of impact of chemical weapons compared to nuclear weapons is illustrated in Table. 4.6. Table 4.6. Comparative evaluation of nuclear and chemical weapons
Authors: Grinin A.S., Novikov V.N.
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