100 facts about work safety! A must-see and must-learn!

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1. What is security? Answer: Safety means being free from threats, danger, harm, and loss. A state in which humanity and the resources of its living environment coexist in harmony, without causing harm to one another and without any potential risks or dangers, is a state free from unacceptable risks of damage. Safety, in the context of human production processes, refers to the state in which the potential damage that the operating conditions of a system may cause to human life, property, and the environment is kept below acceptable levels. 　　 2. What is an accident? 　　Answer: An accident refers to an unexpected incident that occurs suddenly during purposeful productive work, forcing production to stop temporarily or causing injuries to people. An accident is an abnormal sudden change in production practice. 3. What is labor protection?
Answer: Labor protection refers to the implementation of organizational and technical measures, in accordance with **laws and regulations, by relying on technological progress and scientific management, to eliminate unfavorable conditions and behaviors that pose a threat to workers’ safety and health. Its purpose is to prevent accidents and occupational diseases, thereby safeguarding the safety and health of workers during the course of their work. The contents of labor protection include: occupational safety, occupational health, protection for female workers, protection for underage workers, as well as working hours and leave systems. 4. What are the “three violations”? Giving illegal instructions, performing illegal operations, and violating labor discipline. 5. What is the principle of four no-harms? Answer: Do no harm to oneself, do no harm to others, avoid being harmed by others, and protect others from harm. 6. What is the principle of “four things not to let go”? Answer: We will not let go until the cause of the accident is clarified; we will not let go until those responsible for the accident are properly dealt with; we will not let go until both the responsible parties and those who need to be educated have received appropriate education; and we will not let go until preventive measures are implemented. 7. The degrees of injury in accidents are classified as: minor injuries, serious injuries, and death. 8. What is a minor injury? Answer: A minor injury refers to an injury that causes physical disability in an employee, or mild functional or organic damage to certain organs, resulting in a slight or temporary loss of working capacity. Generally refers to injured workers who are unable to work for more than one working day, but whose injuries do not qualify as serious. 9. What is considered a serious injury? Answer: A serious injury refers to an injury that results in limb amputation or severe damage to organs such as the eyes, ears, etc. Generally, it leads to long-term functional impairments in the body or significant loss of working capacity. The resulting disability results in a loss of more than 105 working days. 10. What is a liability accident? Answer: It refers to an accident caused by the negligence of the relevant persons. 11. What is a non-responsible accident? Answer: It refers to accidents that occur as a result of natural forces and are irresistible, or accidents that happen due to limitations in current scientific and technological capabilities and are difficult to predict. 12. What is a sabotage accident? Answer: It refers to an accident deliberately caused in order to achieve a certain purpose. 13. If employees suffer injury or death due to illness during the course of their work, can this be treated as a workplace accident? Answer: If injuries or deaths occur during the work process due to illness, and after diagnosis by a hospital at or above the county level and investigation by the labor authorities, it is confirmed that the condition was caused by the employee’s own illness, then it is not treated as an employee injury or death accident. 14. What is China’s current safety management system? (WeChat subscription: Safety Management Dictionary) Answer: Enterprises bear full responsibility, industry authorities carry out management, **supervision and public oversight are in place, and workers must abide by rules and regulations. 15. What are the emergency principles in case of an industrial accident? Answer: Rescue the injured, preserve the accident scene, and report to the relevant authorities promptly. 16. The core of all types of work safety systems is the work safety responsibility system. 17. Safety inspections are an important step in identifying and eliminating unsafe factors. 18. An unsafe condition refers to the physical conditions that lead to accidents. Unsafe behavior refers to human errors that can cause accidents. 19. What are the tasks of enterprise safety production education? It is about striving to improve the safety competence of the workforce, raising employees’ awareness of the importance of safe production, enhancing their sense of responsibility in this regard, increasing their willingness to abide by rules and regulations as well as labor discipline, strengthening their understanding of the legal aspects related to safe production, and improving their technical knowledge in safety matters as well as their ability to handle accidents using the appropriate safety techniques. 20. What is the content of team safety training? 　　1. Understand the tasks and functions of the position, the production characteristics, production equipment, and safety devices. 　　2. Understand the job-related safety regulations and safety operating procedures. 　　3. Understand the specific usage methods of protective equipment, tools, and apparatuses for the position. 　　4. Understand the accidents that have occurred in the position and the lessons learned from them. 21. What are protective grounding and neutral grounding? Answer: Protective grounding is intended to prevent the risk of electric shock caused by insulation failure; it involves closely connecting those metal parts that could develop dangerous voltages with respect to ground in the event of a fault, and this is known as protective grounding. Grounding to neutral involves connecting the metal casing or frame of electrical equipment, whose live parts are insulated, to the neutral wire in a direct grounding system. 22. What are the requirements for installing temporary electrical wires? Answer: 1. Height above the ground – not less than 2.5 meters indoors, not less than 3 meters outdoors, and not less than 5 meters when crossing roads. 2. The insulation of the wires must be good. 3. Wires must not come into contact with flammable, explosive, or high-temperature/humid pipes and equipment. 4. The ends of the wires should be wrapped with insulating tape or placed in a temporary power distribution socket panel. 23. What is the flash point? What is the ignition point? 　　Answer: For any flammable liquids and the vapors of such liquids, when they come into contact with an open flame, a flash fire can occur; the temperature at which this happens is known as the flash point. The temperature at which a substance begins to burn is called its ignition point. 24. What are the main causes of fires in electrical circuits? 　　Answer: (1) Inter-wire short circuit ； (2) The fuse is not installed properly ； (3) Overload ； (4) Poor contact at the joints or connections results in high resistance, causing the wires to heat up. 25. What are the causes of mechanical injuries? 　　Answer: 1. The mechanical equipment does not meet safety requirements ； 2. Inadequate protection during use, no protective facilities available ； 3. Inadequate safety operation procedures and insufficient safety training. 26. In the event of an electrical fire at a construction site, the power supply must be cut off first, and the fire should be extinguished using sand, carbon dioxide, \"1211\" extinguishers, or dry powder extinguishers; water or foam extinguishers should not be used. 27. Fires are classified into four categories: A, B, C, and D. 1. Category A fires: refer to fires involving solid materials. Such substances often have organic properties and generally produce hot embers when burned. Such as fires involving wood, cotton, wool, linen, paper, etc. 2. Class B fires: refer to fires involving liquids and meltable solids. Such as fires involving gasoline, kerosene, crude oil, methanol, ethanol, asphalt, paraffin, etc. 3. Class C fires: refer to gas fires. Such as fires involving gas, natural gas, methane, ethane, propane, hydrogen, etc. 4. Class D fires: refer to metal fires. This refers to fires involving potassium, sodium, magnesium, titanium, zirconium, lithium, aluminum-magnesium alloys, etc. 28. The Work Safety Law of the People’s Republic of China was promulgated on June 9, 2002, and came into effect on November 1, 2002. On August 31, 2014, the 10th meeting of the Standing Committee of the 12th National People’s Congress adopted a decision by the Standing Committee of the National People’s Congress regarding the amendment to the Work Safety Law of the People’s Republic of China, which came into effect on December 1, 2014. The newly revised Work Safety Law was passed and issued on June 10, 2021, and came into effect on September 1, 2021! 29. The prevention and control of occupational diseases adhere to a prevention-first approach combined with prevention and control measures, and implement classified management and comprehensive treatment. 30. For victims in work-related accidents who have stopped breathing and their heart has stopped beating, the success rate of rescue within 5 minutes is very high. 31. The best time to extinguish a fire in a building is within 5 to 7 minutes of it starting; after that, one must try to escape from the fire scene. 32. If an employer forces workers to carry out work in violation of regulations and at high risk, resulting in serious casualties and severe consequences, the persons responsible shall be held criminally liable in accordance with the law. 33. The safe current level that the human body can tolerate is 9 milliamps for males and 6 milliamps for females. A current of 50 milliamps can be life-threatening and is known as a lethal current. 34. National Fire Prevention Day is November 9th. 35. Classification of safety colors and their meanings: Red: Prohibition signs; Blue: Instruction signs; Yellow: Warning signs; Green: Guidance signs. 36. When high-voltage wires fall to the ground, no one is allowed to enter within 20 meters of the point where the wires have broken. 37. In a three-wire cable, the red wire represents the live wire. 38. The “Labor Safety and Health Symbol” features a green cross representing labor safety and health at its center, surrounded by a pattern formed by modified gears and olive leaves. The gear on the left side symbolizes labor, the Great Wall, and China, while the olive leaves on the right side represent peace, prosperity, and happiness. 39. If the person who has been electrocuted is seriously injured, with stopped breathing or a stopped heartbeat, every effort should be made to perform artificial respiration and chest compressions. 40. When using a fire extinguisher to put out a fire, aim it at the base of the flames. 41. Work carried out at heights of 2 meters or more above the reference level for falling heights, where a fall is possible, is called work at height. 42. When carrying out demolition work at a construction site, it must be done from top to bottom. 43. The storage area for acetylene cylinders should be kept away from direct sunlight, and the distance from open flames must be at least 15 meters. 44. The pathways of fire spread include heat conduction, heat radiation, and heat convection. 45. For acts of negligently causing a fire that have not yet resulted in serious losses, a warning, a fine, or detention for up to ten days shall be imposed as punishment. 46. The scope of safe production includes personal safety and equipment safety. 47. The “four comprehensives” principle of safety production management refers to all employees, the entire process, all aspects, and 24/7 coverage. 48. The seat belt should be inspected once after 2 years of use. 49. When working at heights, tools must be kept in a portable tool box or tool bag. 50. **It is stipulated that the weight of a safety helmet should not exceed 400 grams.** 51. If a “D” mark is indicated on a safety helmet, it indicates that the helmet has insulating properties. 52. The belt should be fastened high and used low. 53. Work in which two or more groups of workers are simultaneously carrying out tasks within the same vertical volume, thereby increasing the risk of object strikes, is known as cross-work. 54. The “three essentials” at a construction site are safety helmets, safety belts, and safety nets. 55. Safe voltage values: 42, 36, 24, 12, 6 volts. 56. Power supply for safe voltage: Powered by a specific power source, including an independent power supply and a safety isolation transformer (composed of two relatively independent coils mounted on the same core). Autotransformers, voltage dividers, and semiconductor devices cannot be used as voltage supply sources. 57. Requirements that must be met for the safe voltage circuit: Ⅰ. Electrical isolation must be implemented between the input and output of the power supply ； 　　II. Circuits operating at safe voltage levels must have no electrical connection to other electrical systems (grounding is not allowed, but the core of the safety isolation transformer should be grounded) ； 　　III. When a safe voltage of 24V or higher is used, protective measures must be taken to prevent direct contact with live parts; exposed live parts are not permitted ； 　　IV. The circuit meets the following conditions: the voltage rating of the components and wires is at least 250V; plugs designed for safe voltages cannot be inserted into sockets with higher voltages. 58. Key points for rescue at an electric shock scene: Quickly disconnect from the power source ； Provide accurate first aid (artificial respiration and chest compressions) ； Provide first aid on the spot ； Treatment must be pursued to the end. 59. What are the working pressure, maximum working pressure, and design pressure of a pressure vessel? What is the relationship between them? What do the working temperature and design temperature of a pressure vessel refer to respectively? (WeChat subscription: Safety Management Dictionary) Answer: Working pressure (also known as operating pressure) refers to the pressure at the top of the vessel during normal operational conditions. The maximum operating pressure refers to the highest pressure that may occur during normal process operation. When the pressure exceeds this value, the safety device on the container will activate. The determination of the maximum operating pressure is related to the working medium. The design pressure refers to the pressure used at the corresponding design temperature to determine the calculated wall thickness of the vessel as well as the dimensions of its components. The Regulations on Safety Supervision of Pressure Vessels stipulate that the design pressure of a vessel shall not be lower than the maximum operating pressure. For pressure vessels equipped with safety relief devices, their design pressure shall not be lower than the opening pressure or burst pressure of such relief devices. The operating temperature of a pressure vessel refers to the temperature of the working medium inside the vessel during normal operation, that is, the temperature of the medium. The design temperature refers to the highest or lowest temperature that the shell wall or the metal components of a vessel may reach under the corresponding design pressure during normal operation. When the temperature of the shell wall or component metal is below -20°C, the design temperature is determined based on the lowest temperature; otherwise, the design temperature is always chosen based on the highest temperature. The operating temperature of a pressure vessel refers to the temperature of the medium, while the design temperature refers to the design temperature of the shell. 60. Starting from the date of manufacture, fire extinguishers (cans) must be retired after reaching the following time limits: Portable chemical foam fire extinguishers — 5 years ； Portable acid-base fire extinguisher—5 years ； Portable water fire extinguisher—6 years ； Portable dry powder fire extinguisher (gas cylinder type) — 8 years ； Portable pressure-storage dry powder fire extinguisher—10 years ； Portable 1211 fire extinguisher—10 years ； Portable carbon dioxide fire extinguisher—12 years ； Cart-type chemical foam fire extinguisher—8 years ； Cart-type dry powder fire extinguisher (gas cylinder type) — 10 years ； Pushcart pressurized dry powder fire extinguisher—12 years ； Cart-type 1211 fire extinguisher—10 years ； Cart-type carbon dioxide fire extinguisher—12 years. Furthermore, extinguishers or gas cylinders that are to be scrapped must have holes made in their bodies, and a clear “Scrapped” label must be attached using adhesive tape; the label should display the word “Scrapped” in letters no smaller than 25mm×25mm ； Year and month of retirement ； Name of the maintenance unit ； Inspector’s signature. Fire extinguishers should be maintained and inspected at least once a year. 61. Classification of chemical pressure vessels: Pressure vessels are classified by purpose into reaction vessels, heat transfer vessels, separation vessels, and storage and transportation vessels. 62. What is a pressure vessel? A pressure vessel is a sealed device used to hold gases or liquids and withstand certain pressures; it is defined as one whose maximum operating pressure is greater than or equal to 0.1 MPa (gauge pressure). 63. The contents of safety inspections for pressure vessels include: 1. The condition of insulation, corrosion protection, and the equipment nameplates. 2. Check whether the container has any cracks, deformation, local bulging, or similar issues. 3. Check for any leaks in all cracks of the container and in the pressure-bearing components. 4. Are the safety accessories complete, sensitive, and reliable? 5. Check whether the foundation has settled or tilted. Are the sturdy screws complete and in good condition? 6. Is there any vibration or friction? 7. Whether the operating pressure, temperature, and component parameters meet the design specifications during operation. 8. Are the operation logs and maintenance records complete and accurate? 64. Toxic effects of common chemicals in the chemical industry: Chlorine (Cl2): A yellow-green gas that is readily soluble in water, alkaline solutions, carbon disulfide, and carbon tetrachloride. Reaction with carbon monoxide can produce phosgene, which is more toxic. Chlorine dissolves in water to form hydrochloric acid and hypochlorous acid, causing local irritation. It primarily damages the mucosa of the upper respiratory tract and bronchi, causing bronchospasm, bronchitis, and peribronchitis; in severe cases, it can lead to pulmonary edema. Inhalation of high concentrations of chlorine causes vagal reflex-induced cardiac arrest, resulting in a \"shock-like\" death. 65. Sulfur dioxide (SO2): a colorless gas with a density 2.3 times that of air. It becomes liquefiable under pressure; the relative density of the liquid is 1.434, and the boiling point is –10°C. Soluble in water, ethanol, and ether. Upon inhalation into the respiratory tract, sulfurous acid and sulfuric acid are formed on the moist mucosal surfaces, causing a strong irritant effect. Inhalation in large amounts can cause laryngeal edema, pulmonary edema, and vocal cord spasm, leading to asphyxiation. 66. Carbon monoxide (CO): a colorless, odorless, and non-irritating gas. Its density is 0.968 times that of air; it is insoluble in water, but soluble in ammonia, ethanol, benzene, and acetic acid. The flame is blue when burning. Once inhaled, carbon monoxide enters the bloodstream through the alveoli. Carbon monoxide forms carboxyhemoglobin with hemoglobin. Carboxyhemoglobin has no oxygen-carrying capacity and does not dissociate easily, resulting in hypoxia in tissues throughout the body. 67. Hydrogen cyanide (HCN): a colorless gas with a bitter almond odor; its density is 0.94 times that of air, its melting point is –13.4°C, and its boiling point is 26°C. Soluble in water, ethanol, and ether. It dissolves in water to form volatile hydrocyanic acid. Hydrogen cyanide has a strong affinity for the trivalent iron ions in oxidized cytochrome c oxidase in the body; by binding tightly to them, the enzyme loses its activity, thereby hindering the process of biooxidation and preventing tissue cells from utilizing oxygen, resulting in internal asphyxiation. 68. Hydrogen sulfide (H2S): a colorless gas with a rotten egg odor; its density is 1.19 times that of air, and its boiling point is –61.8°C. Soluble in water, ethanol, glycerin, and petroleum solvents. 69. Basic methods of extinguishing fires: I. Cooling method: Spray the fire extinguishing agent directly onto the burning object to lower its temperature below the ignition point, thereby stopping the combustion ； Alternatively, the extinguishing agent can be sprayed on the materials near the source of fire to prevent new fire points from forming due to the heat radiation from the flames. Cooling fire suppression is a major method of extinguishing fires, with water and carbon dioxide being commonly used as extinguishing agents to cool down and put out the fire. Fire extinguishing agents do not participate in the chemical reactions that occur during combustion during the fire extinguishing process. This method belongs to the category of physical fire extinguishing methods. II. Isolation fire extinguishing method: Remove the surrounding unburned combustible materials or isolate them from the material that is on fire, thereby cutting off the supply of combustible material and stopping the combustion due to the lack of fuel. The specific methods are: 1. Remove combustible, flammable, explosive, and oxidizing materials from around the source of fire ； 　　2. Close the valves on the pipelines for flammable gases and liquids to reduce and prevent flammable substances from entering the combustion area ； 　　3. Try to prevent the spread of flammable and combustible liquids ； 　　4. Demolish flammable buildings adjacent to the fire source to create a zone that prevents the spread of the fire. 　　III. Smothering fire extinguishing method: Prevent air from entering the burning area or dilute the air with non-flammable gases, so that the burning material does not receive enough oxygen and thus goes out. The specific method is as follows: 1. Cover the burning material with non-flammable or slowly flammable materials such as sand, cement, wet burlaps, or wet quilts ； 　　2. Spray firefighting agents such as mist water, dry powder, or foam over the burning material ； 　　3. Fill the container or equipment where a fire has occurred with water vapor or inert gases such as nitrogen or carbon dioxide ； 　　4. Enclosed buildings, equipment, and openings on fire ； 　　5. Spray non-flammable gases or liquids (such as carbon dioxide, nitrogen, carbon tetrachloride, etc.) onto the area where the fire is occurring or onto the burning material. 70. Glossary of Terms 1. Illegal operation: Refers to the act of violating various regulatory documents issued by **, as well as various rules and regulations established by enterprises, institutions, and their management bodies to reflect the objective laws of safe production. These include procedures, rules, regulations, guidelines, methods, and systems related to process technology, production operations, labor protection, safety management, etc., as well as notices and decisions concerning safe production. 　　2. Safety production responsibility system: The safety production responsibility system is a system established in accordance with safety production regulations, whereby leaders at various levels, functional departments, engineering and technical personnel, and operators are each held accountable for ensuring safety in the work process. 　　3. Potential accident hazards: Refer generally to human unsafe behaviors, unsafe conditions of objects, and management deficiencies within a production system that can lead to accidents. 　　4. Work-related injuries and fatalities: refer to physical injuries and acute poisoning incidents that occur to employees during the course of work. That is, injuries (i.e., minor injuries, serious injuries, death) and acute poisoning incidents that occur when employees are working at their regular posts, or even though they are not working there, due to unsafe equipment and facilities in the enterprise, poor working conditions and environments, inadequate management, as well as being assigned by the enterprise’s management to carry out activities related to the enterprise outside its premises. 5. Work-related injuries and fatalities: refer to physical injuries and acute poisoning incidents that occur to employees during the course of work. That is, injuries (i.e., minor injuries, serious injuries, death) and acute poisoning incidents that occur when employees are working at their regular posts, or even though they are not working there, due to unsafe equipment and facilities in the enterprise, poor working conditions and environments, inadequate management, as well as being assigned by the enterprise’s management to carry out activities related to the enterprise outside its premises. 71. The primary task of occupational health is to improve working conditions and prevent occupational hazards. 72. On a macro level, according to statistics, the main causes of accidents are unsafe conditions of objects and unsafe behaviors of people. 73. The types of safety inspections include: daily safety inspections, regular safety inspections, specialized safety inspections, seasonal safety inspections and safety inspections after holidays, as well as ad-hoc safety inspections. 74. Comrade Zhou Enlai put forward the slogan “Safety first” in 1957. 75. The scope of special operations and personnel includes: (WeChat subscription: Safety Management Dictionary) (1) Electrical work operations. Includes workers involved in power generation, transmission, transformation, and distribution; those responsible for the installation, operation, maintenance, and testing of electrical equipment; as well as electricians working in underground mines. 　　(2) Metal welding and cutting operations. Includes welders and cutters. 　　(3) Operations of lifting machinery (including elevators). Includes operators of lifting machinery (including elevators), riggers, signal handlers, and installation and maintenance workers. 　　(4) Operation of motor vehicles within the enterprise. Drivers of various motor vehicles that operate in production areas such as corporate docks and freight yards, as well as at construction sites. 　　(5) Work involving working at heights. Includes workers who perform tasks such as climbing heights of over 2 meters for installation, demolition, and maintenance, as well as workers who clean the surfaces of high-rise buildings. 　　(6) Boiler operations (including water quality testing). Operators of pressure-bearing boilers, and personnel responsible for testing boiler water quality. 　　(7) Pressure vessel operations. Positions include pressure vessel tankers, inspectors, transport escorts, and operators of large air compressors. 　　(8) Refrigeration operations. Includes refrigeration equipment installers, operators, and maintenance technicians. 　　(9) Blasting operations. Includes surface engineering blasting and underground blasting workers. 　　(10) Mine ventilation operations. It includes main fan operators, gas extraction workers, ventilation and safety monitoring personnel, as well as wind and dust measurement workers. 　　(11) Mine drainage operations. Workers involved in the main drainage pumps of mines, and those working at tailing dam sites. 　　(12) Mine safety inspection operations. Includes safety inspectors, gas inspectors, and explosion-proof inspection technicians for electrical equipment. 　　(13) Mine hoisting and transportation operations. Including hoist operators, (uphill and downhill) winch operators, fixed belt conveyor operators, signalmen, and tank handlers (hookmen). 　　(14) Excavation (stripping) operations. Includes coal miner operators, tunneling machine operators, rock scraper operators, and drill operators. 　　(15) Mine rescue operations. 　　(16) Handling of hazardous materials. Operators handling hazardous chemicals, civil explosives, and radioactive materials, as well as transport escorts and storage supervisors. 　　(17) Other operations approved by the **Work Safety Supervision and Administration Bureau. 76. Special operation personnel must be at least 18 years old, but those engaged in blasting work and gas inspection in coal mines must be at least 20 years old. 77. Special operation personnel may take up their posts only after passing professional technical training and examinations and obtaining an operation permit. 78. Except for motor vehicle driving, marine vessel driving, and engine operation, in accordance with **relevant regulations, other special operation certificates must be renewed every 2 years. 79. Cylinders with visible protrusions (bulges) on their body shall be scrapped. The storage area for acetylene cylinders should be kept away from direct sunlight, and the distance from open flames must be at least 10 meters. 80. In welding operations, to ensure the safety of the operator, the shielding sheet is generally replaced after being used for a total of 8 hours. 81. Gas welding is a welding method that uses the flame from gas combustion as a heat source. 82. Flammable materials should not be stored at the location where welding work is carried out. 83. The three main safety accessories of a boiler are the safety valve, pressure gauge, and water level gauge. Improper long-term treatment of boiler water can lead to a boiler explosion. The external inspection, which is part of the boiler inspection schedule, is carried out once a year. 84. When the crane is approaching its end point, the power should be turned off in a timely manner, trying to avoid using the travel limiters as much as possible. 85. Before using a DC welding machine for welding, the voltage must not exceed 110 volts. 86. When opening the cylinder valve, the operator should stand to the side. 87. The red line marked on the dial of the pressure gauge indicates high operating pressure. 88. The main responsibility of the signalman for lifting equipment is to give the operator appropriate signals during the lifting process, so as to ensure smooth progress of the lifting operation. 89. 12-volt lighting should be used when repairing boilers and pressure vessels. 90. An act that causes a fire due to human negligence and results in serious consequences constitutes the crime of negligently starting a fire. 95. The core temperature of a cigarette butt can reach 700–800°C, which exceeds the ignition points of flammable materials such as cotton, linen, woolen fabrics, paper, and furniture. Discarding cigarette butts carelessly can easily lead to fires. 96. The main function of machine guards is to prevent operational accidents. 97. Hand tools should not be placed on the edge of the workbench because they can fall and injure people. 98. Precautions for using gas cylinders: 1. When moving or storing gas cylinders, shock-absorbing washers should be installed, and the safety caps should be tightened to protect the control valves, preventing them from turning accidentally and reducing the risk of collisions. 　　2. When carrying gas cylinders filled with gas, it is best to use a special stretcher or trolley; they can also be lifted horizontally by hand or rotated vertically. However, it is absolutely not allowed to move the switch valves by hand. 　　3. When gas cylinders filled with gas are transported by vehicle, they must be properly secured to prevent them from rolling or colliding during transit ； When loading and unloading, handle it gently; throwing, sliding, or any other method that may cause impact is prohibited. 　　4. Cylinders filled with gases that can cause combustion or explosion when in contact with each other (such as hydrogen cylinders and oxygen cylinders) must not be transported together or stored in the same place, nor should they be stored together with other flammable and explosive materials. 　　5. If the gas cylinder body has defects, the safety accessories are incomplete or damaged, and safe use cannot be ensured, it must not be sent for gas filling again; it should be taken to a relevant authority for inspection, and only after passing the inspection can it be used. 99: Boilers operate under high temperature and pressure, and are constantly subjected to the erosion by substances such as smoke, fire, and water vapor, as well as the effects of their operating conditions ； Pressure vessels and gas cylinders are used under conditions of high temperature and pressure in some cases, and under low temperature and cryogenic conditions in others. Some of them contain flammable, explosive, toxic, highly toxic, or corrosive substances. The metal materials used in these devices can suffer from corrosion, wear, deformation, fatigue, decarburization, and changes in their microstructure. The accessories and auxiliary equipment associated with these devices may also develop faults or get damaged due to operational factors. If these issues are not detected and addressed in a timely manner, it could lead to severe damage to the equipment as well as accidents resulting in injuries or deaths. Therefore, in order to keep track of the condition of equipment such as boilers, pressure vessels, and gas cylinders in a timely manner, identify and eliminate potential hazards, and ensure the safe and economical operation of such equipment, it is necessary to conduct regular inspections and repairs on them. 100. Why is it necessary to treat the water quality in boilers? Answer: The quality of water used in boilers has a close relationship with the safe and economical operation of these boilers. Poor boiler water quality can cause scale to form on the heating surfaces, affecting heat transfer and leading to fuel waste. In severe cases, it can cause the boiler drum to bulge and pipe blockages, leading to accidents. Various impurities present in the boiler water, including gases, can also cause metal corrosion and reduce the service life of the boiler ； Excessive impurities can also affect the quality of the steam, causing it to contain water and resulting in foaming. Therefore, strengthening water treatment for boilers is an important aspect in ensuring their safe and economical operation.