2. Properties of ammonia, safety measures, and emergency response principles

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Special warning: Can form an explosive mixture with air； Inhalation can cause toxic pulmonary edema. Physical and chemical properties: It is a colorless gas at normal temperature and pressure, with a strong pungent odor. It can be liquefied at 20°C and 891 kPa, releasing a large amount of heat. Liquid ammonia has a very large coefficient of volume change when the temperature changes. Soluble in water, ethanol, and ether. The molecular weight is 17.03, the melting point is -77.7°C, the boiling point is -33.5°C, the gas density is 0.7708 g/L, the relative vapor density (air = 1) is 0.59, the relative density (water = 1) is 0.7 at -33°C, the critical pressure is 11.40 MPa, the critical temperature is 132.5°C, the saturated vapor pressure is 1013 kPa at 26°C, the explosion limit is 15%–30.2% (by volume), the auto-ignition temperature is 630°C, and the maximum explosion pressure is 0.580 MPa. Primary uses: Mainly used as a refrigerant and in the production of ammonium salts and nitrogen fertilizers. Hazard Information [Risk of combustion and explosion] Highly flammable; it can form explosive mixtures with air, and combustion and explosion can occur in the presence of open flames or high temperatures. 【Reactive reaction】 It undergoes violent chemical reactions when in contact with fluorine, chlorine, etc. 【Health hazards】 It has a strong irritating and corrosive effect on the eyes and respiratory mucosa. Acute ammonia poisoning causes irritation of the eyes and respiratory tract, bronchitis or peribronchitis, pneumonia, and toxic pulmonary edema may occur in cases of severe poisoning. High concentrations of ammonia can cause reflexive respiratory and cardiac arrest. Can cause burns to the eyes and skin. PC-TWA (Time-Weighted Average Allowable Concentration) (mg/m3): 20; PC-STEL (Short-Term Exposure Allowable Concentration) (mg/m3): 30. 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 tight sealing to prevent leaks; provide adequate local and general ventilation in the work area. Keep it away from sources of fire and heat, and smoking is strictly prohibited in the work area. Workshops where ammonia is produced or used, as well as areas for storing ammonia, should be equipped with ammonia leak detection and alarm devices. Explosion-proof ventilation systems and equipment must be used, and at least two sets of positive-pressure air respirators, long-tube gas masks, heavy protective clothing, and other protective gear should be available. Wear chemical safety goggles, anti-static work clothes, and rubber gloves. When the concentration at the workplace exceeds the limit, operators should wear filtered gas masks. Frostbite should be prevented when in contact with liquids. Pressure vessels and equipment such as storage tanks should be equipped with safety valves, pressure gauges, level gauges, and thermometers. They must also have safety devices that provide remote monitoring and alarm functions for pressure, level, and temperature. Interlock devices should be installed to connect them to presses, power supplies, pipeline pressures, ventilation systems, or appropriate absorption devices. Emergency shut-off devices must be installed on key storage tanks. Avoid contact with oxidizers, acids, and halogens. Safety warning signs should be installed in production and storage areas. During transfer, cylinders and containers must be grounded and bonded to prevent the generation of static electricity. Handle with care during transportation to prevent damage to the cylinders and accessories. The use of electromagnetic cranes, binding with chains, or using the bottle valve as a lifting point is prohibited. Equipped with fire-fighting equipment of appropriate types and quantities, as well as emergency response equipment for leaks. 【Special Requirements】 【Operational Safety】 (1) It is strictly prohibited to use ammonia pipelines as welding ground wires. It is strictly prohibited to strike pipes and valve bodies with iron tools to avoid generating sparks. (2) The following protective measures should be taken when working in an environment with ammonia gas: ——Equip appropriate ammonia gas detectors and protective devices according to the different working environments, and implement proper personnel management to keep these detectors and protective devices in standby mode ； ——A wind vane should be installed in the working environment ； ——The air compressor of the air supply unit should be placed on the upwind side ； ——When performing maintenance and emergency repair work, an ammonia detector and a positive-pressure air respirator should be carried. (3) During filling, use a universal joint piping filling system to strictly prevent overfilling. 【Storage Safety】 (1) Store in a dedicated, cool, and well-ventilated warehouse. Keep away from flames and heat sources. The warehouse temperature should not exceed 30°C. (2) Store separately from oxidizers, acids, halogens, and food chemicals; mixed storage is strictly prohibited. Store the tank away from sources of fire and heat. Use explosion-proof lighting and ventilation facilities. The use of mechanical equipment and tools prone to generating sparks is prohibited. The storage area should be equipped with emergency equipment for handling leaks. (3) Liquid ammonia cylinders should be placed at a distance of at least 5 meters from the work area, in a well-ventilated location. (4) Pay attention to lightning and static electricity protection; the ammonia storage tanks within the plant (workshop) should be equipped with lightning and static electricity protection facilities in accordance with the Requirements for Lightning Protection Design of Buildings (GB 50057). 【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. (2) Special tank trucks should be used for transportation by tank truck. The flame arrester (spark extinguisher) installed on the tank truck must be in good condition. Tank trucks and delivery trucks must be equipped with anti-static trailing cables ； The tank truck must be equipped with at least 2 dry powder or carbon dioxide fire extinguishers and explosion-proof tools ； Prevent direct sunlight. (3) When transporting cylinders by vehicle, the openings of the cylinders must always face to the right, in the direction of travel. The stacking height shall not exceed the vehicle’s protective barriers, and the cylinders should be secured with wooden blocks to prevent them from rolling. It is prohibited to mix items with conflicting properties in the same vehicle, as well as to allow unrelated persons to ride along. Keep away from sources of fire during transportation; do not park in areas with open flames or in crowded places, and someone should be present to watch over the vehicle when it is parked. In the event of a leak or fire, drive the vehicle to a safe place to extinguish the fire or seal the leak. (4) Pipelines for transporting ammonia should not be laid near heat sources ； When pipes are laid above ground, protective measures should be taken in areas with high pedestrian traffic and those prone to being struck by vehicles or foreign objects, along with the installation of clear warning signs ； When ammonia pipes are installed overhead, they should be laid on supports or trestles that are not combustible. Under the installed ammonia pipelines, no buildings unrelated to these pipelines shall be constructed, nor shall flammable materials be stored there ； The color and markings on the outer wall of ammonia pipelines shall comply with the provisions of \"Basic Identification Colors, Identification Symbols, and Safety Markings for Industrial Pipelines\" (GB 7231). Principles of first aid 【First aid measures】 Inhalation: Quickly move the affected person to a place with fresh air. Keep the airways clear. If there is difficulty breathing, provide oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention. Skin contact: Immediately remove contaminated clothing and thoroughly rinse with 2% boric acid solution or plenty of water. Seek medical attention. Eye contact: Immediately lift the eyelids and rinse thoroughly with plenty of flowing water or saline for at least 15 minutes. Seek medical attention. 【Fire extinguishing method】 Firefighters must wear full-body fire and gas-resistant suits and extinguish the fire from the upwind side. Cut off the gas supply. If the gas supply cannot be cut off, it is not allowed to extinguish the flame at the leak site. Use water spray to cool the container, and move it as far as possible from the fire to an open area. Extinguishing agents: fog water, alcohol-resistant foam, carbon dioxide, sand. 【Leak Emergency Response】 Eliminate all ignition sources. A safety zone is established based on the affected area caused by the gas, and uninvolved personnel are evacuated to a safe area from the side wind and upwind direction. It is recommended that emergency responders wear fully enclosed chemical protective suits equipped with built-in positive-pressure self-contained breathing apparatus. In the event of a liquefied gas leak, care should also be taken to prevent frostbite. Do not touch or cross the spill. Seal the source of leakage as much as possible. Prevent the spread of gases through sewers, ventilation systems, and confined spaces. If possible, turn the container upside down to allow the gas to escape rather than the liquid. Construct dikes or dig pits to contain the liquid spill. Neutralize with acetic acid or other dilute acids. It can also be diluted and dissolved with sprayed water, while dikes are built or pits are dug to contain the large amount of wastewater generated. If possible, use an exhaust fan to send the residual gas or escaping gas to a scrubber tower or a fume hood connected to the tower. In the event of a leak from a cylinder that cannot be sealed, it can be immersed in water. It is advisable to install water or dilute acid spraying facilities in the tank area. Isolate the leak area until the gas has dissipated. Leaking containers must be handled properly; they should be repaired and inspected before reuse. Isolation and evacuation distances: For small leaks, initial isolation should be 30 m; evacuation is required at 100 m during the day and 200 m at night in the downwind direction ； In case of a major leak, initially establish a 150m exclusion zone; evacuate people downwind at a distance of 800m during the day and 2,300m at night.