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Chlorine is an essential raw material (auxiliary substance) for various industries and sectors. Today, I will share some facts related to chlorine to help everyone gain a better understanding of it. 1. The number of persons entering the chlorine production facility (plant) and storage areas at the same time should not exceed 3; the number of workers in the liquid chlorine filling area should not exceed 2, and the number of persons during the handling of abnormal conditions should not exceed 6. Adopt engineering and management measures to reduce the number of personnel on site and prevent catastrophic accidents that result in mass deaths and injuries. 2. Chlorine reacts with carbon steel at temperatures above 121°C; therefore, welding is prohibited on liquid chlorine pipelines. “The 5.12” Lixing Rubber accident occurred because of a lack of knowledge in this area: electric heating was used instead of hot water to vaporize liquid chlorine, which led to the perforation and leakage of the liquid chlorine pipelines. 3. Liquid chlorine should not be contained within sealed pipelines; if there is liquid chlorine inside such pipelines with the valves at both ends closed, pressure relief measures must be in place to prevent overpressure and leakage due to temperature increases. The liquid chlorine level in liquid chlorine storage tanks/cylinders, metering tanks, and vaporizers should not exceed 80% of the container’s volume. 4. Liquid chlorine pipelines shall not be laid underground, nor shall they cross public areas other than the plant site. 5. Chlorine pipelines should use dedicated valves, chlorine-resistant gaskets, and lubricants that do not react with chlorine. 6. For liquid chlorine transfer pumps, shaft-sealed pumps should not be used. For example: shielded pumps, magnetic pumps, etc. 7. A burst disc should be installed in front of the chlorine safety valve; pressure monitoring should be provided between the safety valve and the burst disc, and the vent line of the safety valve should lead to the accident chlorine absorption unit. 8. The liquid chlorine storage tank building, bottle warehouse, filling area, and vaporization room shall have a closed structure; no liquid absorption spray systems such as those using water or alkalis, nor alkali neutralization tanks, shall be installed inside. In the event of a liquid chlorine leak, it is prohibited to spray water directly on the tank; instead, the leak site should be turned upward (toward the gas phase where the leak occurs), the leak should be sealed, and the liquid chlorine removed. 9. An ORP or pH meter should be installed in the chlorine refrigerant water system to continuously monitor for any leaks of liquid chlorine within the heat exchange equipment. 10. Temperature monitoring should be installed on titanium equipment and pipelines in the chlorine treatment process to prevent wet chlorine from turning into dry chlorine and reacting chemically with the titanium. 11. When the temperature of wet chlorine is below 12°C, chlorine octahydrate (Cl2·8H2O) forms and accumulates, blocking the pipes. 12. Pressurized chlorine pipelines should be equipped with measures to prevent the condensation of liquid chlorine. If liquid chlorine is entrained in gaseous chlorine, it can cause problems such as overpressure or excessive reaction rates. 13. The vaporization of liquid chlorine should be carried out using a full-vaporization process, with the outlet chlorine temperature to be controlled between 75°C and 85°C. With a special vaporizer (steam heating), the temperature must not exceed 120°C. 14. A needle valve should be installed at the outlet of the liquid chlorine cylinder to control the chlorine flow rate; the cylinder valve should not be used directly for adjusting the chlorine flow rate. The cylinder valve of the chlorine cylinder must be opened using a special wrench. 15. The pipes connected to the valve of the liquid chlorine cylinder should be made of annealed copper tubes or stainless steel tubes that have undergone solution treatment. 16. Liquid chlorine storage tanks should be equipped with two or more level gauge instruments based on different principles. Glass plate level gauges shall not be used in liquid chlorine storage tanks. 17. Flammable and combustible materials shall not be stored within 20 meters of the liquid chlorine storage tank building and the bottle warehouse. Liquid chlorine storage should be equipped with at least one tank of the largest capacity as a backup tank for emergency use in case of liquid chlorine incidents. The liquid chlorine storage tank building should have a sealed structure; where possible, the liquid chlorine loading and unloading areas should also be enclosed. 18. Forklifts should not be used to load or unload liquid chlorine cylinders. Liquid chlorine heavy cylinders must not be stored outdoors. 19. Liquid chlorine storage tanks should be equipped with backup accident tanks, enabling tank transfer operations to be carried out remotely without operators entering the chlorine plant. 20. For routine testing of nitrogen trichloride emissions and samples, vaporization should not be used; instead, liquid-phase processing is required to prevent the concentration of nitrogen trichloride in the liquid phase and subsequent explosion.