Sometimes we see reports of people being frostbitten by dry ice that creates smog effects in stage performances. Why does dry ice frostbite people? How to deal with frostbite by dry ice?

Dry ice is not ice, but solid carbon dioxide. At normal temperature, the pressure is 6079.8 kPa. Carbon dioxide is condensed into a colorless liquid, and then evaporates rapidly under low pressure, and then condenses into pieces of compacted ice-snow-like solid substances. The temperature is minus 78.5°C, which forms dry ice.

Because solid carbon dioxide looks like ice and has an extremely low temperature of -78.5°C, and no water is produced during the sublimation cooling process, it is called dry ice.

Compared with ordinary ice cubes (below 0°C), dry ice has the characteristics of small size and better cooling effect, and dry ice is non-toxic, has no peculiar smell, and has bactericidal effect, which can effectively prevent the reproduction of bacteria in food and maintain the freshness of food. Therefore, it is widely used in the preservation, storage and transportation of fresh food, aquatic products, and processed meat products, as well as in the pharmaceutical industry and low-temperature treatment of cold-embedded metals. Because of its sublimation characteristics of no moisture and extremely low temperature, it is used in the cleaning industry of industrial machinery and equipment. , has the advantages of high efficiency and environmental protection, and is currently widely used abroad, but it has just emerged in China.

Why does dry ice frostbite people? It quickly absorbs a lot of heat when sublimated

Anyone engaged in stage design and production knows that dry ice is often used to create cloud and fog effects on the stage. Because after the dry ice is placed at room temperature, as the air pressure decreases and the temperature increases, the dry ice vaporizes. The dry ice absorbs heat during the sublimation process, which reduces the temperature around the stage, and the water vapor in the air will use the dust particles in the air as a medium to condense into small water droplets, which look like clouds in large areas. According to the same principle, dry ice is also applied to artificial rainfall and fire extinguishing and equipment surface cleaning.

Then, why does dry ice hurt people? Dry ice sublimates when it comes in contact with human skin. In the process of sublimation, it will absorb a lot of heat. When the dry ice directly contacts the human body, it will cause frostbite to the human skin tissue. Therefore, in daily life, when taking dry ice, be careful not to touch it directly with your hands, otherwise, your skin will be frostbitten in an instant.

When holding dry ice with bare hands, the dry ice will stick to the skin immediately, so you must use tools to take the dry ice. If it is a very short-term contact, cotton gloves can play a role in preventing frostbite. However, if the contact time is too long, such as ten or twenty minutes, cotton gloves will not work. The correct way to deal with frostbite after being frostbitten by dry ice is to go indoors at around 22-25°C, or immerse in warm water at 38-42°C to rapidly raise body temperature, instead of baking with fire, soaking in cold water, or rubbing with snow. Elevate the injured area as much as possible and keep it warm.

Precautions for contact with dry ice:

1. Do not touch dry ice directly with your hands

The temperature of dry ice is minus 78.5°C. When it sublimates rapidly, the temperature of the surrounding air will drop rapidly. Direct contact can cause skin tissue to be excessively stimulated by cold and form trauma.

2. Dry ice sticking to the wound can be warmed up with warm water

If the wound is stuck to the fabric of the clothes when you are frostbited by dry ice, do not tear off the fabric recklessly, and wash it with warm water. After the ice cubes melt, the fabric will fall off automatically. It cannot be baked with fire, nor can it be soaked in cold water.

Dry ice storage Dry ice is difficult to store, but the longest is 10 days

Generally speaking, the storage time of dry ice is relatively short. Even if it is stored in a special Liandek dry ice freezer, it can only be stored for 5-10 days. After the storage period, the dry ice will form ice clusters or even gasify. Also, don't store dry ice in well-sealed, small containers. This is because dry ice is extremely volatile and produces a gas 1000 times larger than the solid area, which creates a huge pressure on the sealed container.

As for the dry ice used for keeping fresh, the best way to deal with it is to discard it directly and let it volatilize naturally, so as to avoid danger caused by improper storage. If you want to continue to store, the better way is to store it in a dry thermos bottle. There is a vacuum layer between the inner wall of the thermos bottle and the outer wall for heat insulation, and the gas generated by the volatilization of dry ice can be released from the gap between the cork and the bottle wall. , reducing the internal pressure. Scientific experiments have shown that this method can generally save a day and a night.