1. Properties of chlorine, safety measures, and emergency response principles

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Special warning: highly toxic; inhalation of high concentrations of the gas can be fatal； The packaging container is at risk of exploding when heated. Physical and chemical properties: At normal temperature and pressure, it is a yellow-green gas with an irritating odor. At room temperature, it is a liquid at pressures above 709 kPa; liquid chlorine is golden yellow in color. Slightly soluble in water, readily soluble in carbon disulfide and carbon tetrachloride. The molecular weight is 70.91, the melting point is -101°C, the boiling point is -34.5°C, the gas density is 3.21 g/L, the relative vapor density (air = 1) is 2.5, the relative density (water = 1) is 1.41 (at 20°C), the critical pressure is 7.71 MPa, the critical temperature is 144°C, the saturated vapor pressure is 673 kPa (at 20°C), and the log Pow (octanol/water partition coefficient) is 0.85. Main uses: Used in the production of vinyl chloride, epichlorohydrin, allyl chloride, chlorinated paraffins, etc ； Used as a chlorinating agent, and also as a disinfectant in water treatment processes. Hazard Information [Flammability and Explosivity] This product is non-flammable, but it can act as a fuel. Most common combustibles can burn in chlorine, and most flammable gases or vapors can also form explosive mixtures with chlorine. When heated, the pressure inside the container or tank increases, and the leaking substances can cause poisoning. 【Active Reaction】 A strong oxidizing agent that reacts with water to produce toxic hypochlorous acid and hydrochloric acid. It reacts with bases such as sodium hydroxide and potassium hydroxide to produce hypochlorite and chloride, and this reaction can be utilized to render chlorine gas harmless. Liquid chlorine reacts violently when in contact with combustibles and reducing agents. It can form explosive mixtures when in contact with petroleum products such as gasoline, hydrocarbons, ammonia, ethers, turpentine, alcohols, acetylene, carbon disulfide, hydrogen, metal powders, and phosphorus. Contact with substances such as hydrophosphines, aluminum, antimony, arsine, bismuth, boron, brass, carbon, and diethylzinc can cause combustion and explosion, releasing toxic fumes. In humid environments, it severely corrodes iron, steel, copper, and zinc. 【Health Hazards】 Chlorine is a highly irritating gas. When inhaled through the respiratory tract, it comes into contact with the moisture on the surface of the respiratory mucosa, resulting in the formation of hydrochloric acid and hypochlorous acid. Hypochlorous acid further decomposes into hydrochloric acid and atomic oxygen, causing local irritation and corrosion. Acute poisoning: In mild cases, symptoms include tearing, coughing, slight expectoration, and chest tightness; signs of tracheobronchitis or peribronchitis may also appear ； In moderate poisoning, bronchopneumonia, focal alveolar pulmonary edema, interstitial pulmonary edema, or asthmatic attacks occur. In addition to an exacerbation of the aforementioned symptoms, patients also experience difficulty breathing and mild cyanosis ； In severe cases, alveolar edema, acute respiratory distress syndrome, severe asphyxia, coma, or shock may occur, along with complications such as pneumothorax and mediastinal emphysema. Inhaling extremely high concentrations of chlorine can cause vagal reflex-induced cardiac arrest or laryngeal spasm, leading to a \"electric shock-like\" death. Eye contact can cause acute conjunctivitis, and high concentrations of chlorine can lead to corneal damage. Skin contact with liquid chlorine or high concentrations of chlorine can cause burns or acute dermatitis in the affected areas. Chronic effects: Prolonged exposure to low concentrations can lead to chronic gingivitis, chronic pharyngitis, chronic bronchitis, emphysema, bronchial asthma, and other conditions. It can cause tooth erosion. Included in the List of Highly Toxic Chemicals. Occupational exposure limit: MAC (Maximum Allowable Concentration) (mg/m3): 1. Safety Measures [General Requirements] Operators must receive specialized training, strictly adhere to operating procedures, master operational skills proficiently, and possess knowledge of emergency response. Ensure strict sealing, provide adequate local and general ventilation; smoking is strictly prohibited in the workplace. Provide safety showers and eye wash stations. Workshops where chlorine is produced or used, as well as areas for storing chlorine, should be equipped with chlorine leak detection alarms, along with at least two sets of heavy-duty protective clothing. Wear chemical safety goggles, anti-static work clothes, and chemical-resistant gloves. When the concentration at the workplace exceeds the limit, operators must wear gas masks; in cases of emergency rescue or evacuation, they should use positive-pressure self-contained breathing apparatus. Pressure vessels and equipment such as liquid chlorine vaporizers and storage tanks should be equipped with safety valves, pressure gauges, level gauges, and thermometers, as well as safety devices that provide remote monitoring and alarm functions for pressure, level, and temperature. Install interlock devices for the rectifier unit with the chlorine compressor, power supply, pipeline pressure, ventilation facilities, or the corresponding absorption units. Emergency shut-off devices should be installed on the chlorine inlet and outlet pipelines. Avoid contact with flammable or combustible materials, alcohols, ether, and hydrogen. Safety warning signs should be installed in production and storage areas. Handle with care during transportation to prevent damage to the cylinders and accessories. During lifting, the gas cylinder should be placed in a specialized basket that meets safety requirements for transportation. The use of electromagnetic cranes, chaining, or using bottle valves as lifting points is prohibited. Equipped with appropriate types and quantities of fire-fighting equipment and emergency response devices for leaks. Containers that have been emptied and may still contain residual harmful substances should be dealt with promptly. 【Special Requirements】 【Operational Safety】 (1) For chlorination equipment, pipelines, and valve gaskets, high-strength chlorine-resistant materials such as asbestos boards, asbestos-rubber sheets, fluoroplastics, and graphite-impregnated asbestos ropes should be used; the use of rubber gaskets is strictly prohibited. (2) When using compressed air to fill liquid chlorine, the moisture content in the air should be ≤0.01%. When filling liquid chlorine using a liquid chlorine vaporizer, it is only allowed to heat the vaporizer with warm water; direct heating with steam is not permitted. (3) Equipment such as liquid chlorine vaporizers, pre-coolers, and heat exchangers must be equipped with waste discharge systems and waste treatment facilities, and the nitrogen trichloride content must be analyzed regularly. If the operator fails to discharge waste in a timely manner as required and handles the process improperly, it can lead to hazards such as nitric trichloride explosions and large-scale chlorine gas leaks. (4) It is strictly prohibited to spray water on the leaking cylinder. (5) Cylinders with a filling capacity of 50 kg and 100 kg shall have a remaining volume of more than 2 kg, while cylinders with a filling capacity of 500 kg and 1000 kg shall have a remaining volume of more than 5 kg. Before filling, ensure there are no foreign objects inside the gas cylinder. (6) During filling, use a universal joint piping filling system to strictly prevent overfilling. 【Storage Safety】 (1) Store in a cool and well-ventilated warehouse; the warehouse temperature should not exceed 30°C, and the relative humidity should not exceed 80%. Direct sunlight should be avoided. (2) It should be stored separately from flammable materials, alcohols, and food chemicals; mixed storage is strictly prohibited. Keep the tank away from ignition sources and heat sources. Keep the container sealed; the storage area should be constructed within a dike below the natural ground level. When storing gas cylinders, empty cylinders and filled cylinders should be kept separately, with clear markings in place. The storage area should be equipped with emergency equipment for dealing with leaks. (3) For units that use large quantities of chlorine cylinders, emergency sealing tools and personal protective equipment should be available on site to address cylinder leaks promptly. (4) It is prohibited to locate storage tank equipment and chlorine treatment systems near densely populated areas such as schools, hospitals, and residential districts, as well as away from frequent access points and emergency exits. (5) The system of \"two-person receipt and dispatch, and two-person custody\" for highly toxic chemicals must be strictly implemented. 【Transportation Safety】 (1) Transport vehicles shall be equipped with signs indicating the transport of hazardous goods, as well as satellite positioning devices with driving record functionality. Without the approval of the public security authorities, transport vehicles shall not enter areas where the passage of hazardous chemicals transport vehicles is restricted. It is prohibited to park in densely populated areas and locations with open flames. During summer, transportation should be done in the morning and evening to avoid exposure to direct sunlight. (2) Vehicles transporting liquid chlorine cylinders are not allowed to cross the river through tunnels. (3) When transporting cylinders with a filling capacity of 50 kg or more by vehicle, they should be placed lying down, with the valve end facing the right side of the vehicle’s direction of travel. They must be secured using wooden blocks to prevent them from rolling, and the stack height shall not exceed 2 layers nor the height of the vehicle’s cargo compartment. It is prohibited to mix items with conflicting properties in the same vehicle, as well as to allow unrelated persons to ride along. It is strictly prohibited to mix or transport it together with flammable or combustible materials, alcohols, food-grade chemicals, etc. The vehicle should be equipped with emergency sealing tools and personal protective equipment, which the escort personnel should know how to use. (4) Handlers must take precautions and wear the necessary protective gear as required ； During transportation, management personnel must be present at the site to supervise unloading and loading ； It is not suitable to transport at night or in low-light conditions, nor in rainy weather. If it is necessary to move the item under special circumstances, approval from the department head must be obtained, and measures such as protection from rain must also be taken ； Smoking during handling is strictly prohibited. (5) When using the liquid chlorine vaporization method to pump liquid chlorine into storage tanks, it is necessary to strictly control the pressure and temperature of the vaporizer. The heating jacket of the kettle-type vaporizer must not cover the bottom; it should be heated with warm water, and heating with steam is strictly prohibited. The outlet water temperature should not exceed 45°C, and the vaporization pressure should not exceed 1 MPa. Principles of emergency response [First aid measures] Inhalation: Quickly move the affected person to a place with fresh air. Keep the airway clear. In case of difficulty breathing, administer oxygen and nebulize a 2% to 4% sodium bicarbonate solution. If breathing and heartbeat stop, perform CPR immediately. Seek medical attention. Eye contact: Immediately separate the eyelids and rinse thoroughly with running water or saline solution. Seek medical attention. Skin contact: Immediately remove contaminated clothing and rinse thoroughly with running water. Seek medical attention. 【Fire extinguishing method】 This product is non-flammable, but the gas supply should be cut off in case of a fire in the surrounding area. Use water spray to cool the container, and move it as far as possible from the fire to an open area. Firefighters must wear positive-pressure self-contained breathing apparatus and full-body fire- and poison-resistant suits to extinguish the fire from the upwind side. Due to the possibility of container explosions in fire scenes, firefighters must operate from explosion-proof shelters. In the event of a chlorine leak, use fine water mist to disperse the leaking gas and keep it away from unaffected areas. Extinguishing agent: Select an appropriate extinguishing agent based on the cause of the fire around. Dry powder, carbon dioxide, water (fog), or foam can be used. 【Leak Emergency Response】 Determine a warning zone based on the area affected by gas dispersion; unrelated personnel should evacuate to a safe area from the crosswind or upwind direction. It is recommended that emergency responders wear fully enclosed chemical protective suits equipped with built-in positive-pressure self-contained breathing apparatus, as well as rubber gloves. If there is a liquid leak, care should also be taken to prevent frostbite. Do not touch or step on the spill. Do not allow the spill to come into contact with flammable materials (such as wood, paper, oil, etc.). Seal the source of the leak as much as possible. Sprayed water suppresses vapor or alters the direction of vapor clouds, preventing water flow from coming into contact with the leak. It is prohibited to direct water at the spill or the source of the leak. If possible, turn the container upside down to allow the gas to escape rather than the liquid. Prevent the spread of gases through sewers, ventilation systems, and confined spaces. Construct dikes to contain the liquid leaks. Neutralize and dilute with a diluted alkaline solution. Isolate the leak area until the gas has dissipated. Keep the area where there is a leak well-ventilated. Specific measures for different leakage situations: In the case of a leak at the sealing gasket of the bottle valve, it is necessary to check whether the tightening nut is loose, and tighten the nut if necessary ； When there is leakage at the outlet of the bottle valve, check whether it is properly closed; close it tightly, or seal the valve opening with a copper hex nut. When the leakage point on the bottle is a hole, sealing materials (such as bamboo sticks, cork, stoppers, etc.) can be used to address it, and care should be taken to secure these sealing materials properly to prevent them from falling off. If the above treatments are ineffective, the leaking gas cylinder should be promptly submerged in an absorption tank containing a sufficient volume of sodium hydroxide or lime water solution to carry out harmless treatment. It is necessary to keep the temperature of the absorption solution below 45°C and its pH at or above 7, in order to prevent the absorption solution from decomposing effectively. Isolation and evacuation distances: For minor leaks, initial isolation should be 60 m; evacuation should take place at 400 m during the day and 1600 m at night in the downwind direction ； In the event of a large-scale leak, an initial isolation zone of 600m is established; evacuations are required within 3500m during the day and 8000m at night in the downwind direction.