At present, dry ice is usually pressurized at room temperature to obtain liquid carbon dioxide, and then evaporated at low temperature. In the evaporation process, part of the liquid is cooled and solidified to obtain dry ice.

Dry ice can be made by a dry ice maker. Its raw material is not direct gaseous carbon dioxide, but liquid carbon dioxide, which still solidifies into solid particles after evaporation and cooling. About 40% of liquid carbon dioxide is converted into solid dry ice.

Dry ice fire extinguisher is the application of dry ice in the field of fire fighting, and it is also one of the important uses of dry ice. Dry ice fire extinguishers are usually called carbon dioxide fire extinguishers, which use liquid carbon dioxide stored in high-pressure gas cylinders as fire extinguishing agents. After pressing the switch, the pressure in the bottle drops, and the liquid carbon dioxide vaporizes into carbon dioxide gas, which insulates the air and achieves the purpose of extinguishing the fire.

No trace is left after fire extinguishing, which is suitable for fire extinguishing in expensive instruments, archives and computer rooms. It does not conduct electricity, so it is also suitable for extinguishing low-voltage electrical equipment and oil fires with electricity, but it cannot be used to extinguish fires of potassium, sodium, magnesium, aluminum and other substances.

Dry ice is a solid form of carbon dioxide, which can neither burn nor help combustion. It covers the surface of burning objects to isolate oxygen from fire fighting.

Using dry ice sublimation to absorb heat, the temperature of combustion products is reduced below the ignition point; At the same time, the density of carbon dioxide produced by sublimation of dry ice is higher than that of air, which does not support combustion. Carbon dioxide covers the surface of burning objects, isolating oxygen and extinguishing fire.