What is dry ice?
Dry ice is essentially a block (or pellets) of frozen carbon dioxide gas (CO2). Compared to regular ice, dry ice is useful because it chills to a lower temperature – a block of dry ice has a surface temperature of -78.5 degrees Celsius. This allows it to preserve contents at a cold temperature, evaporate when exposed to oxygen and unlike wet ice, not create water residue.
In normal atmospheric conditions, dry ice undergoes a process of sublimation, which means as it breaks down, it turns directly from a solid to a gas. The gas dry ice generates is colourless that may form a white vapour from condensed atmospheric moisture.
How is it used?
Due to its ability to stay much colder than regular ice, it is commonly used to preserve items that need to remain cold or frozen. These are commonly used by:
- Hospitals and clinics – to preserve biological samples or vaccines
- Food processing and distribution – to preserve frozen foods, meat or vegetables
- Industrial cleaning
- Theatrical and special effects
Dry ice is commonly used for airline shipping because it can stay colder for longer periods of time, such as a long-haul international flight.
Is dry ice considered dangerous goods?
Yes. Dry ice is classified as class 9 “miscellaneous” dangerous goods. Miscellaneous dangerous goods are a class of dangerous goods without one specific hazard. Dry ice is considered hazardous, in particular during transportation, because it releases a large volume of carbon dioxide gas as it evaporates which can cause an explosive hazard if contained.
If not handled correctly, dry ice can also cause freeze burns, and the increase of vapor pressure in a sealed package can cause the container to explode.
As dry ice emits carbon dioxide that displaces oxygen, in a confined space, it takes up a lot of oxygen, causing potential suffocation for people or animals in the same confined space.
How can dry ice be handled and transported safely?
When handling dry ice, protective gear must always be worn – that includes protective gloves. Prolonged contact with the skin can cause skin cells to freeze and cause serious injury, similar to a burn.
Dry ice should always be stored in a dangerous goods regulator approved insulated container with proper air ventilation and insulations (such as Styrofoam). Dry ice should never be stored in an air-tight container because the carbon dioxide gas will cause the container to expand and possibly explode – this includes jerrycans, steel drums and plastic bags.
It should also never be stored in an unventilated room, cellar, auto or boat holds. The sublimated carbon dioxide gas will sink to low areas and replace the oxygenated air, which can cause suffocation if breathed exclusively. Dry ice should also never be stored in a refrigerator freezer, but when storing large quantities, it should be stored in a commercial storage container.
For more information about the safe storage, handling, and transportation of dry ice, please contact us.
Disclaimer: the information in this article is not intended to be used as a complete guide, it won’t suit every dry ice situation or type of transport as it contains recommendations of a general nature. Compliance requirements and safety standards can only be met by applying professional advice specific to each transportation situation. If you’d like more information or require advice for your dangerous goods management system, please contact us here.