Dry Powder Fire Extinguisher: Dry powder fire extinguishers are filled with dry powder extinguishing agent. Dry powder extinguishing agent is a dry, free-flowing fine powder used for fire extinguishing. It is composed of inorganic salts with fire-extinguishing properties and a small amount of additives, dried, pulverized, and mixed into a fine solid powder. By covering the flame surface, it isolates the air, preventing further combustion and thus achieving the fire extinguishing effect.
Wind-Powered Fire Extinguisher: Wind-powered fire extinguishers eliminate the third condition (temperature) to extinguish the flame. They blow a large amount of air at high speed towards the flame, rapidly lowering the surface temperature of the burning object. When the temperature drops below the ignition point, combustion stops. This is the principle of a wind-powered fire extinguisher.
The structure of a wind-powered fire extinguisher is simple: an electric motor, fan blades, a duct, and a battery.
Foam Fire Extinguisher: Al2(SO4)3 + 6NaHCO3 == 3Na2SO4 + 2Al(OH)3↓ + 6CO2↑
Carbon Dioxide: Carbon dioxide has a high density, approximately 1.5 times that of air. At normal pressure, liquid carbon dioxide vaporizes instantly; generally, 1 kg of liquid carbon dioxide can produce about 0.5 cubic meters of gas. Therefore, during fire extinguishing, carbon dioxide gas can displace air and surround the surface of the burning object or distribute itself in a relatively confined space, reducing the oxygen concentration around the combustible material or within the protected space, thus suffocating the fire. Additionally, when carbon dioxide is released from its storage container, it rapidly vaporizes from liquid to gas, absorbing some heat from the surroundings and providing a cooling effect.
Carbon dioxide fire extinguishers are mainly used to extinguish initial fires involving valuable equipment, archives, instruments, electrical equipment below 600 volts, and oil.
Water fire extinguishers use water as the extinguishing agent. Water has low viscosity, high thermal stability, high density, and high surface tension at room temperature. It is an ancient and widely used natural extinguishing agent, easy to obtain and store. It primarily extinguishes fires through cooling and suffocation. Because each kilogram of water, when heated from room temperature to its boiling point and completely evaporated, can absorb 2593.4 kJ of heat, it utilizes its ability to absorb sensible and latent heat to exert a cooling and extinguishing effect, which is unparalleled by other extinguishing agents. Furthermore, the water vapor formed after water vaporization is an inert gas and expands in volume by approximately 1700 times. During fire extinguishing, the water vapor produced by water vaporization occupies space in the combustion zone, dilutes the oxygen content around the burning material, and hinders the entry of fresh air into the combustion zone, greatly reducing the oxygen concentration and thus achieving the purpose of suffocation. When water is sprayed in mist form, the specific surface area of the water droplets and mist droplets increases significantly, enhancing the heat exchange between water and fire, thereby strengthening its cooling and suffocation effects. In addition, it can also dilute some flammable and combustible liquids that are easily soluble in water; the water mist generated by a strong jet can emulsify flammable and combustible liquids, rapidly cooling the liquid surface and reducing the rate of flammable vapor production, thus achieving the purpose of extinguishing the fire.
Portable fire extinguishers are lightweight fire extinguishers. They are characterized by an extinguishing agent fill volume of less than 500 grams, a pressure of less than 0.8 MPa, and are single-use only, not refillable. Based on the type of extinguishing agent, portable fire extinguishers include: 1211 fire extinguishers (also known as aerosol halon fire extinguishers); portable dry powder fire extinguishers (also known as lightweight dry powder fire extinguishers); and portable air foam fire extinguishers (also known as lightweight air foam fire extinguishers). Portable fire extinguishers are suitable for home use. Portable 1211 fire extinguishers and portable dry powder fire extinguishers can extinguish initial fires on liquefied petroleum gas stoves and cylinder valves, or gas stoves, as well as fires involving hot pots and burning solid combustibles such as wastepaper baskets. Portable air foam fire extinguishers are suitable for initial fires caused by oil pans, kerosene stoves, oil lamps, and candles, and can also extinguish fires involving burning solid combustibles.
There are three conditions for combustion: the substance to be burned, oxygen, and temperature.