Ductile Water Supply Manhole Cover
Ductile Water Supply Manhole Cover made of ductile iron to use water supply manhole top and other places, such as road side pavement and so on.
Manhole cover, ductile manhole cover, ductile iron manhole cover, cast iron manhole. Runchun Casting (Zhoushan) Co., Ltd. , https://www.en124casting.com
Preliminary study on prevention and disposal of liquid ammonia leakage accident
Liquid ammonia is widely used in the ice-making and refrigeration industries due to its cost-effectiveness. For example, in Qidong City, Jiangsu Province, over 200 ice-making and refrigeration companies located in six coastal and Yangtze River ports use ammonia-based refrigeration systems. However, the hazardous nature of liquid ammonia cannot be ignored. It is a colorless, toxic gas with a strong, irritating odor. Its aqueous solution is alkaline and highly soluble in water. Liquid ammonia is commonly used as a refrigerant, but direct contact can cause severe frostbite. The flammability range of ammonia gas is between 15.7% and 27.4%, meaning that when mixed with air or oxygen, it can form an explosive mixture. In addition, containers holding liquid ammonia can explode if exposed to heat. Ammonia can also cause serious harm to the skin, eyes, and respiratory system, leading to coughing, bronchospasm, acute pulmonary edema, and even blindness or suffocation.
Preventing liquid ammonia leakage accidents is crucial for fire brigades at the grassroots level. Based on investigations and practical experiences from recent ammonia leakage and explosion incidents, several key prevention measures have been identified. First, ammonia is classified as a Class B flammable gas and is stored under pressure in steel cylinders or tanks. Regular inspections of these containers are essential to ensure safety. Storage areas should be cool, well-ventilated, and away from heat sources, sunlight, and incompatible substances like chlorine, fluorine, and acids. During handling, care must be taken to avoid damage to the cylinder or valve. When transporting, vehicles should avoid high temperatures and be equipped with proper safety devices such as pressure gauges and valves. Additionally, the ammonia compressor room must meet strict fire protection standards, including explosion-proof electrical equipment, emergency pressure relief systems, and fire suppression facilities like water mist hydrants.
In the event of a leakage, immediate action is necessary. First, establish a warning zone based on the situation, and park vehicles and personnel upwind and on higher ground. Personnel involved in the response must wear appropriate protective gear, such as chemical-resistant suits and air-breathing apparatus. Direct contact with liquid ammonia requires additional cold protection. Fire sources and flammable materials should be removed quickly, and the area should be ventilated. If a cylinder is leaking, non-sparking tools should be used, and the leak should be directed upwards to minimize flow. If valve closure fails, consider submerging the cylinder in water or a dilute acid solution, or moving it to an open area for decontamination. Water mist or flower-shaped water jets can be used to disperse the gas, while precautions should be taken to prevent it from entering sewers or controlled areas. In case of fire, apply water mist, anti-solvent foam, sand, or COâ‚‚ to extinguish the flames. Cool the container walls with large volumes of water and move movable objects out of the danger zone if possible. If signs of impending explosion, such as loud venting sounds or discoloration of the container, are observed, evacuate immediately.