What is the cooling principle of CO₂ Fire Extinguisher?

Among fire extinguishing equipment, CO₂ fire extinguisher is popular for its unique working principle and high efficiency. It can effectively extinguish flames and has good cooling capacity. Understanding the cooling principle of CO₂ fire extinguisher will help us better understand its role in fire extinguishing.

1. Basic structure of CO₂ fire extinguisher

The main components of CO₂ fire extinguisher include gas cylinder, release valve, nozzle and pressure gauge. When the fire extinguisher is activated, the internal high-pressure carbon dioxide gas is ejected through the release valve to form a strong airflow, which quickly achieves the effect of fire extinguishing. The cooling principle plays a vital role in this process.

2. Physical properties of carbon dioxide
Carbon dioxide (CO₂) is a colorless and odorless gas. Its density at normal temperature and pressure is greater than that of air. When CO₂ is released from a high-pressure state to a low-pressure state, it will expand rapidly and cool down. This process is called adiabatic expansion of gas, which is the basis of the cooling capacity of CO₂ fire extinguisher.
Adiabatic expansion: In high-pressure gas cylinders, carbon dioxide is stored in liquid form. When the release valve is opened, liquid carbon dioxide quickly turns into gas and absorbs heat from the surrounding environment during the expansion process. According to the laws of thermodynamics, the gas will reduce its temperature when it expands, resulting in a cooling effect.
Phase change cooling: When carbon dioxide changes from liquid to gas, it absorbs a large amount of latent heat. This process not only causes the temperature of the released gas to drop sharply, but also further enhances the cooling effect. The absorption of latent heat can effectively reduce the temperature of the fire source and inhibit the continued burning of the flame.

3. Application of cooling principle in fire extinguishing
Reducing the temperature of the fire source: CO2 fire extinguishers quickly reduce the temperature of the fire source by releasing low-temperature carbon dioxide gas. Under normal circumstances, the combustion of flames requires a certain temperature and heat. After cooling, the temperature of the fire source can be reduced and the combustion reaction can be quickly suppressed.
Reduce oxygen concentration: When extinguishing a flame, the CO2 fire extinguisher not only reduces the temperature by cooling, but also reduces the oxygen concentration required for combustion by discharging carbon dioxide. This dual effect allows the flame to be extinguished quickly, ensuring the effectiveness of the fire extinguishing effect.
Suitable for electrical fires: CO2 fire extinguishers are particularly suitable for electrical fires because they do not leave any chemical residues during the fire extinguishing process. The characteristics of cooling carbon dioxide enable it to effectively extinguish electrical fires without causing further damage to the equipment.

4. Precautions in use
Although CO2 fire extinguishers perform well in cooling and extinguishing fires, users still need to be careful when using them.
Keep a safe distance: When using, you should keep a certain distance from the fire source to ensure effective fire extinguishing while protecting your own safety.
Aim at the root of the flame: When spraying, you should aim at the root of the flame, not the top, so that you can extinguish the fire more effectively.
Regular inspection: Regularly check the pressure and effectiveness of the fire extinguisher to ensure that it can work properly in an emergency.

The cooling principle of the CO2 fire extinguisher is based on the adiabatic expansion and phase change cooling characteristics of carbon dioxide, which allows it to quickly reduce the temperature while extinguishing the flame. This unique mechanism improves the fire extinguishing efficiency and also makes it perform well in dealing with electrical fires and liquid fires. Understanding the cooling principle of CO2 fire extinguishers will help us better master fire-fighting knowledge, improve fire prevention awareness, and ensure that we can respond quickly and effectively in emergency situations.