Dry ice is the solid form of carbon dioxide. Unlike regular ice made from water, dry ice does not melt into a liquid when it warms; instead, it transitions directly into a gas in a process called sublimation. This unique property makes it an extremely effective chilling agent for keeping items frozen without leaving behind any watery residue. Its temperature is approximately -78.5 degrees Celsius, or -109.3 degrees Fahrenheit. This characteristic is utilized for industrial cooling, preserving sensitive biological samples, and creating dramatic, low-lying fog effects for entertainment purposes.
Where to Purchase Dry Ice
Acquiring dry ice for personal use is straightforward, as it is stocked in numerous retail locations. Many major grocery store chains and large warehouse stores carry dry ice, often near the front of the store or in the frozen goods section. These retailers sell the product in blocks, which are suitable for general cooling needs and tend to last longer than smaller forms.
For specialized needs, such as smaller pellets, dedicated ice companies or welding supply stores are reliable options. Before visiting any location, call ahead to confirm availability, especially if you require a specific form or a substantial amount. Dry ice sublimates continually, so it is best to purchase it as close as possible to the time you intend to use it.
Essential Safety Precautions
Handling dry ice requires safety measures to avoid personal injury. The substance’s extremely low temperature poses a risk of thermal injury, which can cause severe frostbite upon direct contact with bare skin. Insulated gloves, such as heavy leather or cryogenic gloves, must always be worn, and you should use tongs or a scoop to move the dry ice when possible.
The second primary hazard is carbon dioxide gas buildup in unventilated areas. As the carbon dioxide sublimates, it releases a large volume of gas, with one pound of ice expanding to about 250 liters of gas. This gas is heavier than air and can rapidly displace the oxygen in a small, enclosed space, leading to a risk of asphyxiation.
Symptoms of overexposure can include headache, confusion, rapid breathing, and loss of consciousness. Dry ice is only used and stored in spaces with adequate ventilation, such as an open room or outdoors. Never store it in walk-in refrigerators, as the gas will settle at low levels and create a dangerous environment.
Buying and Transport Logistics
Dry ice is commonly sold in large blocks or smaller pellets, with blocks offering a slower sublimation rate for extended cooling periods. The best container for transport is an insulated cooler, such as a thick Styrofoam chest, which helps to slow the sublimation process.
The container must never be completely sealed or airtight. As the solid CO2 sublimates into gas, the pressure inside a sealed vessel will build up quickly, risking rupture or explosion. The insulated container should have a loose-fitting lid or some form of venting to allow the carbon dioxide gas to escape safely.
During vehicle transport, place the vented container in the trunk or cargo area, which is separate from the passenger cabin if possible. If the dry ice must be transported inside the vehicle, keep the windows partially cracked to ensure continuous ventilation and prevent the accumulation of carbon dioxide gas. Five to ten pounds of dry ice will last up to 24 hours in a standard insulated cooler at room temperature.