Daily Safety Technology Quiz (2016.9.3)

For closed transfer or pipeline transfer, enhance ventilation if the substance is volatile.

(1) Preventive and control measures for poisoning and pollution accidents caused by hazardous chemicals 　　① Substitution. The most ideal way to control and prevent the hazards of chemicals is to avoid using toxic, harmful, flammable, and explosive chemicals, but this is difficult to achieve. The common approach is to use non-toxic or low-toxicity chemicals in place of those that are toxic and harmful, and to use combustible chemicals instead of highly flammable ones. 　　②Change the process. Although substitution is the preferred approach for controlling the hazards of chemicals, there are currently very few alternatives available; especially for technical and economic reasons, it is inevitable to produce and use harmful chemicals. At this point, the hazards associated with chemicals can be eliminated or reduced by changing the process. Just as acetaldehyde was previously produced from acetylene using mercury as a catalyst, it has now evolved to be manufactured from ethylene through oxidation or chlorination, without the need for a mercury catalyst. By changing the process, mercury hazards were completely eliminated. 　　③Isolation. Isolation involves using measures such as sealing off areas and setting up barriers to prevent workers from being directly exposed to harmful environments. The most common isolation method is to completely enclose the equipment used in production or operation, so that workers do not come into contact with chemicals during use. Another common isolation method is to separate the production equipment from the control room. 　　④Ventilation. Ventilation is the most effective measure for controlling harmful gases, vapors, or dusts in the workplace. Through effective ventilation, the concentrations of harmful gases, vapors, or dusts in the air of the workplace are kept below safe levels, thereby ensuring the health of workers and preventing fires and explosions. 　　Ventilation is divided into local exhaust ventilation and general ventilation. Local exhaust ventilation involves enclosing the source of pollution and extracting the polluted air; it requires less airflow, is cost-effective, and facilitates purification and recycling. General ventilation, also known as dilution ventilation, works by supplying fresh air to the work area and removing polluted air, thereby reducing the concentration of harmful gases, vapors, or dusts in that area. Total ventilation requires a large volume of air, which cannot be purified and recycled. For point-source diffusion, local exhaust ventilation can be used. When using local exhaust ventilation, the source of pollution should be kept within the range controlled by the ventilation hood. To ensure the high efficiency of the ventilation system, it is crucial that the design of the ventilation system is reasonable. For installed ventilation systems, regular maintenance is necessary to ensure they function effectively. 　　⑤Personal protective equipment. When the concentration of hazardous chemicals in the workplace exceeds safe levels, workers must use appropriate personal protective equipment. Personal protective equipment cannot reduce the concentration of hazardous chemicals in the workplace, nor can it eliminate such chemicals; it merely serves as a barrier to prevent harmful substances from entering the human body. The failure of the protective equipment itself means the disappearance of the protective barrier; therefore, personal protection cannot be regarded as the main means of controlling hazards, but only as an auxiliary measure. Protective equipment mainly includes head protection devices, respiratory protection devices, eye protection devices, body protection gear, and hand and foot protection gear. 　　⑥Hygiene. Hygiene includes two aspects: keeping the workplace clean and maintaining the personal hygiene of workers. Regularly cleaning the workplace, properly disposing of waste and spills, and keeping the workplace clean can also effectively prevent and control chemical hazards. Workers should develop good hygiene habits to prevent harmful substances from adhering to their skin and from penetrating into the body through it. 　　(2) Prevention of fires and explosions involving hazardous chemicals. Theoretically, the basic principles for preventing such accidents are to prevent and restrict the formation of flammable and explosive systems ； Eliminate all types of ignition sources ； Prevent and restrict the spread of fires and explosions. 　　①Prevent the formation of combustion and explosion systems. Control in accordance with the hazardous properties of the substance ； Prevent the spillage of flammable materials ； inert gas shielding ； Ventilation replacement ； Safety monitoring and interlocking. ②Safe control of process parameters. In the chemical and petrochemical production processes, process parameters mainly refer to temperature, pressure, flow rate, and material ratios. Strictly controlling process parameters within safe limits as required by the process specifications, in order to prevent overheating, overpressure, and material leakage, is one of the basic measures for fire and explosion prevention, as well as a fundamental guarantee for ensuring safe production. ③Eliminate the ignition source. Sources of fire that can cause accidents include open flames, hot surfaces, impact friction, spontaneous heating, electrical sources, static electricity sparks, heat from chemical reactions, and light exposure; therefore, scientific and strict management of such fire sources is necessary. ④Measures to prevent the spread of fires and explosions. Measures to restrict the spread of fires and explosions include fire arrestors, fire suppression systems, explosion relief devices, and isolation. 　　(3) Safety in the transportation and storage of hazardous chemicals 　　(I) Safety techniques during transportation 　　Accidents involving chemicals during transportation are relatively common; therefore, a thorough understanding of the safe transportation of chemicals and familiarity with the relevant regulations in this regard are of great importance for reducing transportation accidents. 　　①To ship hazardous materials, relevant certificates must be presented, and the procedures must be handled through the designated departments such as those in the railway, transportation, and shipping sectors. The items being shipped must correspond to the descriptions listed on the shipping manifest. For hazardous items that are not included in the national list of permitted items, a technical assessment report issued by the relevant authorities must be provided for approval. 　　②Personnel responsible for loading and unloading hazardous materials shall wear the appropriate protective equipment depending on the nature of the hazardous materials being handled. Loading and unloading must be done gently; dropping, dragging, applying heavy pressure, or causing friction is strictly prohibited. The packaging containers must not be damaged, and attention should be paid to the labels as well as to proper stacking of the materials. 　　③Before loading or unloading hazardous materials, the vehicles (ships) and handling equipment must be properly ventilated and cleaned to ensure that no residues remain; for vehicles (ships) carrying highly toxic substances, they must be thoroughly washed after unloading. 　　④When transporting items such as explosives, highly toxic substances, radioactive materials, flammable liquids, and combustible gases, transport vehicles that meet safety requirements must be used; the use of battery-powered vehicles, dump trucks, forklifts, bicycles, etc., for transporting explosives is prohibited. 　　⑤When transporting explosive, highly toxic, and radioactive materials, a dedicated escort must be assigned, with no fewer than 2 escorts. 　　⑥Vehicles transporting hazardous materials must maintain a safe speed and keep an appropriate distance between vehicles; overtaking, speeding, and forced passing are strictly prohibited. The routes taken to transport hazardous materials must be approved in advance by the local public security traffic management authorities; transportation must take place along designated routes and at specified times, and it is not allowed to drive or stop on busy streets. 　　⑦Motor vehicles transporting flammable and explosive materials shall be equipped with flame arresters on their exhaust pipes, and must display a “Hazardous Materials” sign. 　　⑧When using steam locomotives for shunting operations, for vehicles carrying flammable and explosive materials, at least 2 buffer cars must be attached, and it is strictly prohibited to allow such vehicles to roll without control. 　　⑨When transporting bulk solid hazardous materials, measures such as fire prevention, explosion prevention, water protection, dust control, and shading should be taken depending on their properties. 　　(II) Safety techniques during storage When storing hazardous chemicals, the following rules must be followed: ① Hazardous chemicals should be stored in designated locations and must not be stored together with other materials. 　　②Hazardous chemicals should be stored in categories and in separate piles; the piles should not be too high or too dense, and there should be sufficient spacing, passages, and ventilation areas between the piles as well as between the piles and the walls. ③ Items that can easily catch fire or explode when in contact with each other, as well as items that require different firefighting methods, should be stored separately. ④ Hazardous chemicals that are prone to burning or exploding when exposed to water should not be stored in damp areas or places where water can accumulate easily. Hazardous chemicals that are prone to combustion or explosion when exposed to sunlight must not be stored in outdoor areas or in places with high temperatures; cooling and insulation measures should also be taken when necessary. 　　⑤The containers and packaging must be intact; if any damage or leakage is detected, immediate safety measures must be taken. 　　⑥Hazardous chemicals that are unstable in nature, prone to decomposition and deterioration, and contain impurities that can pose risks of fire and explosion should be regularly inspected, temperature-checked, and analyzed to prevent spontaneous combustion and explosions. 　　⑦Tests, repackaging, packing, welding, and other operations that may cause fires are prohibited in warehouses storing hazardous chemicals or near open-air stacks. 　　⑧No one is allowed to stay in the warehouse, and a fire safety check should be conducted and the power supply turned off at the end of work.

Substitution, process modification, isolation, ventilation, personal protection, hygiene.

Principles: (1) Substitution: Replace toxic substances with non-toxic ones, and replace highly toxic substances with less toxic ones； (2) Isolation: Seal off the source of danger or increase the distance between the operator and harmful substances ； (3) Ventilation: Use general or local ventilation to remove or reduce the concentration of harmful substances in the air ； (4) Use personal protective equipment.

①Alternative. ②Change the process. 　　③Isolation. 　　④Ventilation. 　　⑤Personal protective equipment. 　　⑥Hygiene.

(1) Substitution: non-toxic replaced by toxic, low-toxicity replaced by high-toxicity； (2) Isolation: Seal off the source of hazard or increase the distance between the operator and harmful substances; (3) Ventilation: Use general or local ventilation to remove or reduce the concentration of harmful substances in the air; (4) Use personal protective equipment.

①Alternative. ②Change the process. 　　③Isolation. 　　④Ventilation. 　　⑤Personal protective equipment. 　　⑥Hygiene.

Substitution, isolation, ventilation, use of personal protective equipment

Use non-toxic or low-toxic alternatives, employ advanced technologies to reduce hazards, and provide personal protective equipment