How should we properly handle gas cylinders? What are the hazards of gas cylinders?

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The hazards of gas cylinders lie not only in their \"high pressure\" but also in their \"contents\". Introduction to common gases in laboratories – Knowing yourself and your enemy ensures success in every battle. 1. Introduction to methane: Methane, also known as biogas, is the simplest organic compound. Molecular weight: 16.04. H—C—H bond angle: 109°28′. Molecular structure: The methane molecule has a tetrahedral shape and is a non-polar molecule. Crystal type: Molecular crystal (sp3 hybridization). Physical properties of methane: Appearance and characteristics: Colorless and odorless gas. Melting point: -182.5°C. Boiling point: -161.5°C. Solubility: Slightly soluble in water; soluble in alcohol and ether. Chemical properties of methane: Stability: It is quite chemically stable and generally does not react with strong acids (such as H2SO4, HCl), strong bases (such as NaOH), or strong oxidizing agents (such as KMnO4). Under appropriate conditions, reactions such as oxidation, pyrolysis, and halogenation occur. Overview of hazards: Health risks: Methane is essentially non-toxic to humans, but at high concentrations it significantly reduces the oxygen level in the air, leading to suffocation. When methane levels in the air reach 25%–30%, it can cause headaches, dizziness, nausea, fatigue, difficulty concentrating, accelerated breathing and heartbeat, and ataxia. If not removed in time, it can lead to death from suffocation. Skin contact with the liquefied product can cause frostbite. Fire and explosion hazard: This product is flammable and poses a suffocation risk. First aid measures: Skin contact: Seek medical treatment if frostbite occurs. Inhalation: Quickly move to a place with fresh air. Keep the airways clear. If there is difficulty breathing, administer oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention. Eye contact: Rinse the affected area with plenty of cold water. Fire-fighting measures: Hazardous properties: Flammable; it can form explosive mixtures when mixed with air, and is prone to combustion and explosion in the presence of heat sources and open flames. It reacts violently upon contact with bromine pentoxide, chlorine, hypochlorous acid, nitrogen trifluoride, liquid oxygen, oxygen difluoride, and other strong oxidizing agents. Harmful combustion products: carbon monoxide, carbon dioxide. Fire extinguishing method: Cut off the gas supply. If the gas supply cannot be cut off, it is not allowed to extinguish the flame at the leak site. Spray the container with water; if possible, move the container away from the fire to an open area. Extinguishing agents: fogged water, foam, carbon dioxide, dry powder. Emergency response to leaks: Take immediate action to evacuate people from the area contaminated by the leak to areas upwind, and establish a barrier to strictly control access. Cut off the source of fire. It is recommended that emergency responders wear self-contained positive-pressure breathing apparatus and anti-static work clothing. Seal the source of leakage as much as possible. Ensure proper ventilation to accelerate diffusion. Sprayed water dilutes and dissolves it. Construct dikes or dig pits to contain the large amount of wastewater generated. Individual protection: Respiratory protection: No special protection is generally required, but it is recommended to wear a self-priming filter-type gas mask (half-mask) in special situations. Eye protection: No special protection is generally required, but safety goggles can be worn in case of high-concentration exposure. Physical protection: Wear anti-static work clothes. Hand protection: Wear general-purpose protective gloves. Other protections: Smoking is strictly prohibited at the work site. Avoid prolonged and repeated exposure. When working inside tanks, confined spaces, or other areas with high concentrations, a supervisor must be present. 2 Introduction to nitrogen: Elemental nitrogen is a colorless and odorless gas under normal conditions. Its solubility in water is very low; at room temperature and pressure, approximately only 0.02 volumes of nitrogen dissolve in 1 volume of water. Liquid nitrogen is slightly soluble in water and ethanol. Content of main components: High-purity nitrogen ≥99.999%; Industrial grade, grade 1 ≥99.5%; grade 2 ≥98.5%. The N2 molecule is the most stable among known diatomic molecules, and the relative molecular mass of nitrogen is 27. 　Under discharge conditions, nitrogen can combine with oxygen to form nitric oxide. Hazards and first aid measures: Fire and explosion hazard: This product is non-flammable. Health hazards: Excess nitrogen in the air reduces the partial pressure of oxygen in the inhaled air, leading to hypoxia and asphyxiation. Skin contact: Seek medical treatment if frostbite occurs. Inhalation: Quickly move to a place with fresh air. Keep the airways clear. If there is difficulty breathing, administer oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention. Fire-fighting measures and emergency response to leaks: Hazardous properties: In the event of high temperatures, the pressure inside the container increases, posing a risk of cracking and explosion. Harmful combustion products: Nitrogen. Fire extinguishing method: This product is non-flammable. Use misted water to keep the containers in the fire area cool. Mist water can be used to accelerate the evaporation of liquid nitrogen, but the water gun must not be directed at the liquid nitrogen. Emergency response: Quickly evacuate people from the area contaminated by the leak to an upwind location, isolate the area, strictly restrict access, and ensure ventilation. Contact control/individual protection: No special protection is generally required for respiratory protection. However, when the oxygen concentration in the workplace air is below 18%, an air respirator, oxygen respirator, or long-tube mask must be worn. Eye protection: Wear a safety face shield. Physical protection: Wear cold-weather clothing. Hand protection: Wear insulated gloves. Other precautions: Avoid inhaling high concentrations. Prevent frostbite. 3 Introduction to Hydrogen Hydrogen is the lightest gas in the world. Pure hydrogen GB/T7445-1995, H2≥99.99%; High-purity hydrogen GB/T7445-1995, H2≥99.999%; Ultra-high-purity hydrogen GB/T7445-1995, H2≥99.9999%. Physical properties of hydrogen: Appearance and characteristics: a colorless and odorless gas. At room temperature, hydrogen is quite stable and does not readily undergo chemical reactions with other substances. Solubility: Insoluble in water, insoluble in ethanol and ether. Melting point (°C): -259.2 Boiling point (°C): -252.8 Chemical properties of hydrogen: When hydrogen burns in air, the flame is pale blue, and the heat released during combustion is three times that of gasoline under the same conditions. High flammability, reducing agent, with a liquid temperature lower than that of nitrogen. Hazard and first aid measures Health hazards: This product is a physiologically inert gas; asphyxiation occurs only at high concentrations due to the reduced oxygen partial pressure in the air. At very high partial pressures, hydrogen can exhibit **activity**. Fire hazard: This product is flammable. Inhalation: Quickly move to a place with fresh air. Keep the airways clear. If there is difficulty breathing, administer oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention. Fire-fighting measures: Hazardous properties: When mixed with air, it can form an explosive mixture that will explode upon exposure to heat or open flames. Gases are lighter than air; when used and stored indoors, any leaks will rise and remain trapped under the roof, making it difficult for them to escape. They can explode when exposed to sparks. Hydrogen reacts violently with halogens such as fluorine, chlorine, and bromine. Harmful combustion products: Water. Fire extinguishing method: Cut off the gas supply and ventilate. Extinguishing agents: fogged water, foam, carbon dioxide, dry powder. Contact control/individual protection: Respiratory protection: No special protection is generally required; an air respirator can be worn in cases of high-level exposure. Eye protection: No special protection is generally required. Wear anti-static work clothes for body protection. Hand protection: Wear general-purpose protective gloves. Other protections: Smoking is strictly prohibited at the work site. Avoid inhaling high concentrations. When working inside tanks, confined spaces, or other areas with high concentrations, a supervisor must be present. 4 Introduction to Oxygen: Oxygen has the chemical symbol O, an atomic number of 8, and an atomic weight of 15.9994; it belongs to group VIA of the periodic table. Oxygen makes up 48.6% of the Earth’s crust, ranking first. Oxygen has three stable isotopes, namely oxygen-16, oxygen-17, and oxygen-18, of which oxygen-16 accounts for 99.759%. Physical properties of oxygen: Color, taste, state: Colorless and odorless gas under standard conditions. Melting point: -218.4°C (turns into a pale blue crystalline solid). Boiling point: -182.9°C (turns into a pale blue liquid). Water solubility: It is not readily soluble in water; under standard conditions, about 30 mL of oxygen can dissolve in 1 L of water. Chemical properties of oxygen: Generally speaking, oxygen has relatively reactive chemical properties. Apart from noble gases, chlorine, bromine, and iodine among the halogens, as well as some inert metals such as gold and platinum, the vast majority of nonmetals and metals can directly undergo oxidation reactions with oxygen. Fire-fighting measures: Hazardous properties: It is a flammable substance; one of the basic elements for combustion and explosion, and it can oxidize most reactive substances. It forms explosive mixtures with flammable substances such as acetylene and methane. Fire extinguishing method: Use water to keep the container cool to prevent it from exploding due to heat, which could exacerbate the fire. Quickly cut off the gas supply. Prevent air circulation. Contact control/Personal protection: Respiratory protection: No special protection is generally required. Eye protection: No special protection is generally required. Body protection: Wear regular work clothing. Hand protection: Wear general-purpose protective gloves. Other precautions: Avoid inhaling high concentrations. 5 Introduction to Helium Helium is a colorless, odorless, non-flammable gas, with an abundance of about 5.2 parts per million in the air. It is completely chemically inert and does not combine with other elements or compounds under normal conditions. With a molecular weight of 4.003, helium is a colorless, odorless, and tasteless gas at room temperature and atmospheric pressure. Hazard overview Health hazards: This is an inert gas; at high concentrations, it can reduce the oxygen partial pressure, posing a risk of asphyxiation. As the helium concentration in the air increases, patients first experience rapid breathing, difficulty concentrating, and ataxia ； This is followed by fatigue and weakness, restlessness, nausea, vomiting, coma, convulsions, leading to death. 6 Introduction to Argon Argon is a colorless, odorless inert gas with a molecular weight of 39.938 and the molecular formula Ar. Under standard conditions, its density is 1.784 kg/m3. Its boiling point is -185.7°C. Introduction to silanes: Silane: SiH4, a colorless and odorless gas with a density of 1.44 grams per liter; its melting point is -185°C and its boiling point is -111.8°C. It is insoluble in water. Disilane: Si2H6, a colorless and odorless gas with a density of 2.87 grams per liter; its melting point is -132.5°C and its boiling point is -14.5°C. It undergoes slight hydrolysis. Other silanes are liquids. Silanes are more chemically reactive than alkanes. All silanes have very poor thermal stability. Appropriately heating high-silane decomposes it into low-silane. Low silanes (such as SiH4) decompose into silicon and hydrogen at temperatures above 500°C. It has strong reducing properties. It can ignite spontaneously in air, producing silicon dioxide and water while releasing a large amount of heat. Silane reaction: SiH4 + 2O2 —— SiO2 + 2H2O. Hazards and first aid measures. Health hazards: Inhaling silane vapors can cause headaches, dizziness, fever, nausea, and excessive sweating ； In severe cases, there is pale complexion, weak pulse, and coma. Fire and explosion hazard: This product is flammable and toxic. Inhalation: Quickly move to a place with fresh air. Keep the airways clear. If there is difficulty breathing, administer oxygen. If breathing stops, perform artificial respiration immediately. Seek medical attention. Fire-fighting measures: Hazardous properties: Can form explosive mixtures when mixed with air. It is highly flammable and explosive when exposed to open flames or high temperatures. It can catch fire on its own when exposed to air. It undergoes violent chemical reactions when in contact with fluorine, chlorine, etc. Harmful combustion products: silicon oxide, hydrogen. Fire extinguishing method: Firefighters must wear gas masks and full protective firefighting suits, and extinguish the fire from the upwind direction. Cut off the gas supply; if it is not possible to cut off the gas supply, do not attempt to extinguish the flame at the leak site. Move the container away from the fire as far as possible to an open area. Water is sprayed to keep the containers at the fire site cool until the fire is extinguished. Extinguishing agents: water, foam, dry powder, carbon dioxide. Emergency response to leaks: Take immediate action to evacuate people from the area contaminated by the leak to areas upwind, and establish a barrier to strictly control access. Cut off the source of fire. It is recommended that emergency responders wear self-contained positive-pressure breathing apparatus and anti-static work clothing. Enter the site from the upwind side. Seal the source of leakage as much as possible. Diluted with spray water. If possible, use an exhaust fan to send the residual gas or escaping gas to a wash tower or a fume hood connected to the tower. Leaking containers must be properly handled, repaired, and inspected before being reused. Contact control/individual protection: Respiratory protection: When the concentration in the air is above the permissible level, it is recommended to wear a self-priming filter-type gas mask (half-mask). In cases of emergency rescue or evacuation, an air respirator should be worn. Eye protection: Wear chemical safety goggles. Physical protection: Wear anti-static work clothes. Hand protection: Wear latex gloves. Other protections: Smoking is strictly prohibited at the work site. When working inside tanks, confined spaces, or other areas with high concentrations, a supervisor must be present.