Dry ice is solid CO2. It exists in its solid state at -78.5°C. At any temperature above this and at atmospheric pressure it will sublimate directly to a gas, skipping the liquid phase. This is why it is referred to as “DRY ICE”
Normal water ice exists in the solid phase from 0°C and lower. As it melts it reverts back to the liquid phase and you are left with water. Weight for weight dry ice has approximately 5 times the cooling power of wet ice.
Yes, providing you observe some simple safety rules. The CO2 gas that sublimates from the dry ice is non-toxic (it is the same gas used in all carbonated drinks), however, in a confined space it poses an asphyxiation risk. Dry ice is also extremely cold at -78.5°C which means that if it is in contact with human skin for longer than a second or two it can lead to a "frostbite" like burn. Protective gloves should always be used. For more details on the safe handling of dry ice please see the “Safe handling” section.
Weight for weight dry ice has approximately 5 times the calorific cooling power when compared with conventional wet ice. Dry ice leaves no liquid residue after it has sublimated and has the benefit of producing a CO2 vapour blanket which, in certain applications, can assist with inhibiting microbial growth. It also provides protection from oxidation.
As dry ice exists in its solid form at -78.5°C it will sublimate at any temperature above this. This means that to effectively store dry ice and to minimize losses it must be stored in a storage container which has good insulating properties. The better the insulation the longer the dry ice will last. It also helps to minimize the free air space in the container and keep the container in as cool an environment as possible and avoid extended periods in hot vehicles. We have a range of containers available for you to store your dry ice in. See the section on storage of dry ice.