1、 Ammonia tank area:
1. Flammability and explosiveness of ammonia
Liquid ammonia can vaporize into ammonia at room temperature and pressure. This gas is flammable in air, but it is generally difficult to ignite. If it comes into continuous contact with a fire source, it will burn and sometimes cause an explosion. If there is grease or other flammable substances, it is more likely to catch fire. When burned in oxygen, it emits a yellow flame and generates nitrogen and water.
Ammonia can also explode in nitrous oxide, with explosive concentrations ranging from 2.2% to 72%. Ammonia is oxidized by oxygen, air, and other oxidants to produce nitrogen oxides, nitric acid, etc. Reacts violently with acids or halogens, and sometimes causes scattering or explosion.
If there is an excess of chlorine, explosive nitrogen trichloride can be generated.
The mixture of ammonia and air can cause an explosion, with an explosion limit of 15% to 27% by volume containing ammonia. Although its explosive limit range is narrower than other flammable gases and less dangerous, it is still necessary to strictly prohibit smoking and fire in practical work, and to prevent air from entering storage tanks, pipelines, gas cylinders and other equipment to form ammonia air mixtures with explosive combustion.
2. The corrosiveness of ammonia
Ammonia is alkaline and highly corrosive. Anhydrous ammonia does not work on most common metals, but if mixed with a small amount of water or moisture, both gaseous and liquid ammonia will strongly react with copper, silver, tin, zinc, and their alloys. It is also prone to react with silver oxide or mercury oxide to produce explosive compounds (such as salts). Reacts with metals such as sodium and magnesium.
Due to the strong corrosiveness of ammonia, iron and iron alloys that do not contain the above-mentioned metals must be selected when selecting equipment and metal materials in contact with ammonia.
3. Toxicity of ammonia
To protect the health of liquid ammonia operators and the safety of the workshop, China has stipulated that the maximum allowable concentration of ammonia in the workshop air is 30 mg/m3. This concentration is safe for working 5 days a week and exposed to 8 hours a day, but if the exposure time is long, the sensitivity of the olfactory organs will change. The effects of different concentrations of ammonia on the human body are shown in Table 1.

Table 1 Effects of Different Concentrations of Ammonia on the Human Body

ammonia concentration（ppm）	Effects on the human body
20	Anyone can smell the odor
>25	Toxic range
25	maximum allowable concentration
100	Start to cause mucosal irritation, can withstand 6 hours
<500	Strongly irritating to eyes and nose, can withstand 0.5~1 hour
~700	It can seriously erode the eyes and nose within a few minutes, and will not cause permanent effects within 0.5 hours
>1000	Severe coughing, bronchospasm, and pulmonary edema causing asphyxia
>2000	Inhalation for 30 minutes is dangerous
>5000	It will die in a short period of time

Ammonia is mainly inhaled through the respiratory tract, and can also be absorbed through the skin. Ammonia is quickly converted into urea when inhaled into the body. The toxic effects of ammonia are mainly caused by the following three points: (1) reducing adenosine triphosphate's obstruction of the tricarboxylic acid cycle and decreasing the activity of cytochrome oxidase; (2) An increase in cerebral ammonia can cause neurological disorders; (3) The strong irritant effect of high concentration ammonia causes tissue dissolution and necrosis.
Inhaling high concentrations of ammonia can cause symptoms such as sneezing, salivation, coughing, nausea, headache, sweating, facial congestion, chest pain, shortness of breath, frequent urination, dizziness, suffocation, discomfort, stomach pain, and urinary obstruction. Stimulating the eyes can cause tearing, eye pain, and visual impairment. Skin contact can cause skin irritation, redness, burns, and erosion.
During chronic poisoning, symptoms such as headache, bad dreams, loss of appetite, irritability, chronic conjunctivitis, chronic bronchitis, bloody sputum, and hearing loss may occur.
When liquid ammonia leaks from storage tanks, gas cylinders, or pipelines, it immediately vaporizes into 884 times its original volume (at 0 ℃), 760 mmHg of gaseous ammonia is mixed with air to form a high concentration ammonia air mixture. Inhaling this mixture may result in death within a few minutes.
4. Filling of liquid ammonia tank
1. Smoking and open flames are strictly prohibited in the work area, and tools and supplies that are prone to sparking are not allowed to be used.
2. Before starting the homework, the safety grounding wire should be connected, and the connection between the pipeline and the pipe joint must be firmly sealed, and the internal air should be discharged.
During loading and unloading operations, operators and drivers are not allowed to leave the site. During normal loading and unloading operations, vehicles must not be started or moved arbitrarily.
When the liquid ammonia is filled to the specified level, close the ammonia inlet valve and tank truck valve, and then open the exhaust valve of the connecting pipe to discharge all the ammonia in the pipeline. The storage coefficient of the liquid ammonia storage tank should not exceed 0.9, and excessive filling should be avoided. The filling level of liquid ammonia should be Class I ammonia.
5. After filling is completed, the filling weight or liquid level must be rechecked. After the filling weight or liquid level is rechecked and qualified, all valves should be restored to the closed position. Confirm that the ammonia gas in the connecting pipe has been discharged before removing the connecting pipe.
After loading and unloading, the loading and unloading records should be carefully filled out and properly stored.
7. Loading and unloading operations are strictly prohibited during thunderstorms or when there are open flames nearby. Loading and unloading operations are strictly prohibited when there is a leakage of flammable, explosive, or toxic media or abnormal pressure inside the tank.
8. The driver of a tanker truck must personally confirm that all connections between the unloading and loading/unloading devices have been properly separated before moving the vehicle body.
5. Emergency measures for liquid ammonia hazards
5.1 Disposal of Liquid Ammonia Leakage
5.1.1 Safety points
1. Liquid ammonia leakage will evaporate into ammonia gas that is lighter than air (relative density of 0.597, air=1), which is easily diffused.
When liquid ammonia leaks, all sources of fire near it (especially on the downwind side) should be quickly removed, removed, or extinguished.
3. Issue an alarm warning to personnel within the area and adjacent areas (especially on the downwind side), and if necessary, evacuate to the upwind side for shelter.
4. Personnel carrying out leak sealing or repair must wear anti-virus equipment.
If the leakage accident has a tendency to expand or may cause other accidents, it should be immediately reported to the safety production supervision, special equipment safety supervision, public security, fire department, and liquid ammonia production manufacturer for assistance.
6. While spraying the leaking area with water, a large amount of liquid ammonia must be diluted with water to prevent it from being left in rivers, lakes, and seas and causing pollution.
5.1.2 Tank Leakage
5.1.2.1 Analysis of Hazardous and Harmful Factors in Liquid Ammonia Storage Tanks
Liquid ammonia storage tanks are liquefied gas storage tanks, and fire, explosion, and poisoning accidents may occur in the storage tank area. Explosions can be divided into physical explosions of the storage tank itself and chemical explosions. Physical explosions refer to the damage caused by ultrasonic waves and explosion fragments to people and objects, while chemical explosions refer to the chemical explosions of ammonia gas caused by the leakage of liquid ammonia from the storage tank. Ammonia is a toxic gas, and tank explosions or liquid ammonia leaks can also cause poisoning accidents.
Analysis of Hazardous and Harmful Factors of Physical Explosion of Liquid Ammonia
(1) If the liquid ammonia storage tank is overpressure due to the following reasons, it may cause a physical explosion of the liquid ammonia storage tank:
a. Incomplete, improperly installed or malfunctioning safety devices;
b. The environmental temperature suddenly rises, causing the liquid ammonia storage tank to overpressure due to the temperature increase;
c. The liquid ammonia storage tank is overloaded.
(2) If the liquid ammonia storage tank has the following defects, it can reduce its pressure bearing capacity and also easily cause physical explosions:
a. Corrosion of internal and external media causes wall thickness reduction, while the outer wall is corroded by the atmosphere and the inner wall is corroded by ammonia;
b. Stress corrosion caused by liquid ammonia is one of the important reasons for tank explosions, and practice has shown that an increase in temperature is conducive to the development of corrosion cracks;
c. Severe plastic deformation of the storage tank;
d. Deterioration of tank material;
(3) If the strength design, structural design, material selection, and anti-corrosion of liquid ammonia storage tanks are not reasonable, it is also easy to cause physical explosions in the tanks.
Analysis of Hazardous Factors for Fire and Chemical Explosion in Liquid Ammonia Storage Tanks
Due to the leakage of liquid ammonia, ammonia gas is formed and mixed with air to reach the explosive limit. When exposed to sources of fire such as open flames and static sparks, it can cause fires and chemical explosions.
(1) Physical explosion of liquid ammonia storage tank causing fire and explosion of ammonia outside the tank;
(2) Leakage of liquid ammonia storage tanks and their accessories (flanges, valves, elbows, etc.), bursting of tank valves and pipelines, leakage of filling systems, failure of system safety devices, and other factors leading to liquid ammonia leakage;
(3) There are sources of ignition such as open flames, static sparks, etc.
Analysis of Hazardous and Harmful Factors of Liquid Ammonia Poisoning
(1) Due to the explosion and leakage of liquid ammonia storage tanks and their accessories, the concentration of ammonia in the air exceeds the safe range value, which may cause poisoning or even death to personnel;
(2) When personnel enter the liquid ammonia storage tank for maintenance, if the internal ammonia concentration does not reach the safe range, it is also prone to poisoning accidents.
5.1.2.2 Safety measures for preventing accidents in liquid ammonia storage tank areas
1. Safety control measures for preventing physical explosions in liquid ammonia storage tanks
(1) Liquid ammonia storage tanks must have good anti-corrosion measures;
(2) Strictly control the filling amount of liquid ammonia storage tanks, and the storage coefficient of liquid ammonia storage tanks should not exceed 0.9. Do not overfill;
(3) Liquid ammonia storage tanks are designed to prevent accidental heating or significant increase in vapor pressure due to excessively high tank temperature;
(4) Minimize the entry of air into the liquid ammonia storage tank as much as possible;
(5) Liquid ammonia storage tanks should be kept at a low working temperature as much as possible, stored at low temperatures, and equipped with sprinkler water and sunshades;
(6) It is necessary to formulate operating procedures and various management systems in accordance with the "Supervision Regulations for Safety Technology of Pressure Vessels", and strictly implement them in accordance with the regulations;
(7) Regular inspections of storage tanks must be conducted in accordance with regulations to promptly detect defects and handle them properly;
(8) Safety devices such as safety valves and pressure gauges must be complete and intact, properly maintained, and regularly calibrated to ensure sensitivity and reliability;
(9) Operators should be trained and qualified before taking up their posts.
2. Safety control measures for preventing fires and chemical explosions in liquid ammonia storage tanks
(1) The ammonia station building complies with the relevant provisions of the "Code for Fire Protection Design of Buildings" (GBJ16-87) (2001 edition);
(2) The ammonia station should be open type, and the ground of the ammonia station building should be acid and alkali resistant. In the explosion-proof area of the ammonia station, explosion-proof design should be adopted, such as setting up explosion-proof equipment and devices, installing embankments, building lightning protection and grounding measures, and special fire-fighting facilities (such as fire hydrants for fire-fighting water). Fences and decorative materials should meet the fire resistance limit requirements;
(3) The number and location of gas detector systems near the liquid ammonia storage tank should be reasonable, and regular inspections should be conducted to prevent their failure;
(4) According to the "Code for Design of Fire Extinguisher Configuration in Buildings" (GB50140-2005), a certain amount of portable dry powder fire extinguishing agent should be installed at appropriate locations in the liquid ammonia storage tank area, and regularly inspected to maintain its effective state;
(5) To indicate the diffusion direction after ammonia leakage, facilitate the selection of on-site work direction by operators, and facilitate personnel evacuation in the event of a leakage accident, it is recommended to install a wind vane at a suitable location;
(6) The selection of materials for pipelines and equipment must be corrosion-resistant to prevent leakage. Liquid ammonia pipelines and ammonia pipelines must be regularly inspected to ensure that there are no leaks in pipelines, valves, flanges, etc., and to prevent insulation layer detachment, object impact, and corrosion thinning;
(7) To prevent the occurrence of fire and heat sources, regularly check the lighting circuit to prevent friction, impact, and static sparks. During maintenance, use copper tools such as copper wrenches to operate and strictly control hot work.
3 Safety control measures to prevent personnel poisoning caused by liquid ammonia storage tanks
(1) Prevent liquid ammonia leakage;
(2) Before entering the liquid ammonia storage tank for maintenance, it is necessary to first ensure that the internal ammonia concentration is within a safe range;
(3) The liquid ammonia filling position is equipped with a self-supporting air respirator.
4 Other safety control measures
(1) The site should be equipped with leak sealing materials and personal protective equipment (such as gas masks, respirators, etc.) to achieve safe leak sealing in the first time, in order to reduce the amount of leakage and minimize the impact of ammonia diffusion;
(2) During the processing, manufacturing, and installation of liquid ammonia storage tanks, strict quality control should be implemented. In production and operation, equipment maintenance should be strengthened to minimize the possibility of liquid ammonia leakage;
(3) For vulnerable and leak prone components such as valves, fittings, flanges, gaskets, etc., regular inspections, maintenance, repairs, and replacements should be carried out to ensure that everything is foolproof;
(4) For liquid ammonia storage tanks, the foundation may sink during operation, and for the convenience of loading and unloading liquid ammonia, the outlet pipeline should be connected with metal hoses or other flexible connections;
(5) From past cases, it is known that liquid ammonia leaks often occur during the loading and unloading process of liquid ammonia. Therefore, the construction party should develop detailed loading and unloading procedures and strictly implement them;
(6) Once a leak occurs, it is necessary to manage open flames and other possible sources of ignition (such as vehicles) in nearby processes and workshops according to the actual situation of the leak, and control ignition sources;
(7) Train staff to master self rescue and mutual aid measures after ammonia leakage and poisoning;
(8) Given the significant risks of fire, explosion, and poisoning associated with the equipment, the company should develop corresponding emergency response plans based on the evaluation results and conduct regular drills to ensure that all emergency facilities are functional in the event of an accident;
(9) Carry out publicity, education and training on safety and health knowledge, with a focus on ammonia poisoning prevention, to enhance employees' awareness of occupational safety and health and self-protection ability.
5.1.3 Pipeline Leakage
If a pipeline leaks, the upstream valve should be immediately closed to cut off the gas source.
If it is not possible to seal the leak, it should be flushed with water until it reaches atmospheric pressure.
5.2 Emergency treatment for liquid ammonia poisoning
5.2.1 Safety points
1. Production equipment must be tightly sealed, with strengthened local exhaust and comprehensive ventilation. Due to the fact that ammonia is lighter than air, the exhaust outlet should be installed at a higher location.
2. Chinese Health Standard (MAC): 30 mg/m3. When the concentration in the air exceeds the standard, it is necessary to wear a gas mask. When rescuing or escaping in emergency situations, air respirators should be worn. Wear chemical eye protection to protect your eyes. Wear protective gloves when necessary. Smoking, eating, and absorbing water are strictly prohibited at work or emergency sites. After leaving the work or emergency site, take a shower and change clothes.
3. Mild acute poisoning patients may exhibit skin and mucosal irritation reactions, leading to rhinitis, pharyngitis, tracheitis, and bronchitis; It can also cause corneal and skin burns. Severe cases may experience laryngeal edema, glottal stenosis, shedding of respiratory mucosal cells, airway obstruction and suffocation, which can lead to toxic pulmonary edema and liver injury. Ammonia can cause reflexive respiratory arrest. If ammonia splashes into the eyes, it can cause lens opacity, corneal perforation, and even blindness.
4. In some cases of poisoning, no symptoms are felt at the beginning of poisoning, but after a few hours, severe pulmonary edema may occur.
5. After entering the scene of the accident, rescue personnel should quickly move the poisoned person to fresh air. During the rescue and transfer process, attention should be paid to the personal safety of the poisoned person. It is not advisable to forcefully drag or pull to cause external injuries, which may worsen the condition. Especially for patients who fall from a high place after poisoning, extra attention should be paid.
6. At the same time as transferring patients, doctors should be promptly sought for diagnosis and treatment. Before the doctor arrives, the patient should be placed indoors at about 20 ℃ to rest, and the buttons and waistbands on the patient's neck and chest clothes should be loosened to maintain smooth breathing. At the same time, pay attention to keeping warm and quiet, closely monitor the patient's consciousness, respiratory status, and circulatory system function, and implement the following first aid according to the condition.
5.2.2 Disposal of Inhaled Ammonia Gas
If a poisoned patient stops breathing, artificial respiration should be performed immediately. There are three types of artificial respiration methods: pressure back, arm shaking, and mouth to mouth (nose) breathing. It is best to use mouth to mouth artificial respiration to prevent further injury caused by stabbing the lungs. The mouth to mouth method first involves keeping the respiratory tract unobstructed, loosening clothes, removing pillows, raising the jaw angle, removing dentures, and removing (suctioning) vomit or other foreign objects.
Operation method: The rescuer is located on one side of the patient and uses one hand to pinch the patient's nostril. The rescuer takes a deep breath and makes close contact between the mouth and the patient's mouth (can be covered with a gauze or handkerchief). The rescuer blows air evenly at a moderate speed, starting with two faster speeds. The patient's chest can be seen to be raised, then leave and let their chest contract to exhale on its own. The rescuer then performs the next blow until spontaneous breathing is restored.
Speed: Blow air 12-16 times per minute for approximately 2 seconds.
If the mouth to mouth breathing method is difficult to perform, the mouth to nose breathing method can be changed, which involves closing the patient's mouth with one hand and blowing air into the nostrils.
If a moderate patient is in a deep coma with no pulsation in the carotid or femoral arteries, if the pupils are dilated, the face appears grayish or cyanotic, and breathing stops or wheezes, it can be considered cardiac arrest and immediate external chest massage should be performed for emergency treatment.
Operation method: Place the patient flat and supine on a hard ground or wooden bed, and the rescuer rides on the patient. Stack the roots of both hands and apply vertical pressure at the junction of the upper 2/3 and lower 1/3 of the sternum, without touching the chest wall with fingers. Lean forward and apply force to the sternum, significantly pressing it down. At this time, when checking the femoral artery, there should be obvious pulsation to be effective. Be careful not to exert too much force to avoid rib fractures and pneumothorax with hemothorax. During two intervals, keep your hands on your chest.
The speed is similar to the heart rhythm, about 70 times per minute for adults and 100-120 times per minute for children, with the best effect. Too many times, heart blood
Insufficient reflux does not increase the effect.
Resuscitation instruction: After stopping the compression, the spontaneous heartbeat is restored.
If a poisoned patient has weak breathing, in order to prevent pulmonary edema, the patient should breathe a mixture of medical oxygen and carbon dioxide (with a content of 5%) or high-purity medical oxygen. If high-purity medical oxygen is used, the exhalation tube end of the respirator should be inserted 4 cm below the water surface in the distilled water filter bottle. Administer oxygen to the patient for 30 minutes per hour, for at least 3 consecutive hours.
4. If the nasal cavity and throat are damaged, the nasal cavity can be washed with 2% boric acid water. If the patient can eat, they can drink 0.5% citric acid or lemon water.
5.2.3 Disposal of liquid ammonia splashing into the eyes
Patients with eye injuries should lift their eyelids (skin) and rinse their eyes with flowing clean water, or immerse their face in a basin filled with clean water and shake it left and right for 15 minutes. Then, within 1 hour, rinse every 10 minutes for 5 minutes. If cleaning with 5% boric acid water or 0.5%~1% alum solution, continuously clean with water during its preparation. Without the permission of a doctor, it is not allowed to use oily ointments such as eye ointment at will.
5.2.4 Handling of Skin Splashing with Liquid Ammonia
When liquid ammonia splashes onto the skin, regardless of whether it is absorbed or not, the following measures should be taken immediately to remove the ammonia from the skin and prevent further harm.
1. Remove contaminated clothing, shoes, socks, gloves, etc.
2. Immediately wash the contaminated skin thoroughly for 15-30 minutes, then rinse with lemon water, vinegar, 5% acetic acid, or 2% boric acid solution, rinse with water, and cover with a dressing soaked in 5% acetic acid, lemon tartaric acid, or hydrochloric acid. Alternatively, wet compress with boric acid solution of 2% or more.
3. For large-scale flushing, it is necessary to avoid catching a cold or flu. If necessary, the flushing agent should be kept at an appropriate temperature, but the principle is to not affect the effectiveness of the flushing agent and to flush it in a timely manner.
When burned (frozen) by liquid ammonia, the first step is to thaw it appropriately and then remove the frozen clothes. When cleaning, pay attention to cleaning the armpits, perineum, skin folds, and any contaminants inside the nails. Do not apply any ointment to the injured area without the doctor's permission.