Just about everybody has heard of dry ice, a super cooling agent with many practical uses—from keeping food and medical samples frozen to creating fog for concerts and Halloween parties. But do you know what dry ice is made of? Or how to use dry ice properly when shipping products that need to stay at extremely cold temperatures?
Dry ice, or solid carbon dioxide, was discovered more than 180 years ago by French inventor Adrien-Jean-Pierre Thilorier. Dry ice possesses the special property of sublimation, meaning that it turns directly from a solid into a gas.
If it’s not handled correctly, dry ice can be hazardous. The extreme cold can actually burn skin, while the gas vapor can cause explosions if not allowed to properly vent. However, used correctly and in the right circumstances, dry ice can be a highly effective coolant for your shipment.
Since dry ice has an exceptionally cold temperature of minus 109.3 degrees Fahrenheit (minus 78.5 degrees Celsius), it’s best reserved for products that absolutely need to be kept very cold, such as frozen foods, sensitive medical supplies and some biologics.
Even then, it could be overkill for certain products that don’t need to stay deeply frozen. “You need to make sure dry ice doesn’t adversely affect the quality of the shipped product,” says Quint Marini, package engineering manager at UPS Package Design and Test Lab. Even when dry ice is an appropriate refrigerant, “it might make sense to combine it with other coolants such as frozen gel packs,” Marini recommends, particularly for transit times of more than one to two days.
Ester Van den Bossche, UPS Temperature True® healthcare packaging manager in Europe, also recommends understanding your options. Certain healthcare products display a particular sensitivity to deep cold temperatures, she explains, in which case dry ice shipping may not be the best choice. “It really depends on the product. UPS can discuss these issues with you to help you determine if dry ice is the right choice for your shipment,” she states.
Once you have decided to ship with dry ice, it’s important to understand the precautions and regulations around it.
Procuring dry ice
You can obtain dry ice from local dry ice suppliers, including some grocery and big box stores. It comes in different shapes and sizes, from pellets and big blocks to slices and little bullets, depending on your need. Dry ice is generally inexpensive, and the larger the quantity you buy, the lower the price per pound.
Handling dry ice
Be very careful when handling dry ice. Its extreme cold temperature can cause physical harm. Handlers must wear goggles to protect eyes, special gloves to safeguard hands, and bibs to ensure dry ice does not spill under clothes. Anyone in the supply chain who may come into contact with dry ice must receive the appropriate level of training.
Storing dry ice
Use special containers for storing dry ice. Do not use containers that are airtight, as the process of sublimation can create severe internal pressure and cause the container to rupture or explode. Do not place dry ice in glass containers, as the glass can crack.
Calculating how much dry ice to use
How much dry ice should you include in your shipment? As a rule of thumb, expect five to ten pounds of dry ice to sublimate every 24 hours. However, the exact sublimation rate will depend on the density of the expanded polystyrene (EPS) insulating foam container you use. The lower the density, the faster the sublimation. Factor this into your shipping calculation.
If you use UPS Temperature True healthcare packaging, you’ll get a higher density EPS foam that comes from preferred suppliers who corroborate the performance level with temperature validation studies. “We can help shippers choose the right solution and calculate the amount of dry ice needed based on the packaging and the time in transit,” explains Van den Bossche. “We also like to add enough dry ice for an additional 24 hours of time to cover any delays.”
Packing with dry ice
Make sure your contents are at the optimal temperature when you’re ready to pack them. Use an EPS foam container for its insulating properties, and place it inside a sturdy, corrugated cardboard box.
Try to keep your contents separate from the dry ice. “The only use for the dry ice is to keep your shipment cold,” says Marini. “You don’t want anything touching the dry ice. You just want to let the dry ice do its job, which is to keep the packaging system cold.” If you are shipping food with dry ice, pack the food carefully to preserve freshness and avoid damage.
As with storage containers, DO NOT seal your dry ice box airtight—the vapor needs to be able to escape or your package could explode. Go lightly with that packing tape.
Labeling for dry ice
For non-medical, non-hazardous air shipments in the United States with 5.5 lbs. or less of dry ice, simply mark the carton with “Dry Ice” or “Carbon Dioxide, Solid,” along with a note of the contents and how many pounds or kilograms of dry ice are included. If you have more than 5.5 lbs. of dry ice, you’ll also need to include a Class 9 diamond hazard label.
If you’re shipping dry ice internationally, IATA regulations apply. You will need to have a signed International Special Commodities (ISC) contract with UPS and a Class 9 diamond hazard label with the amount of dry ice noted on the label.
Help with dry ice shipping
Shipping with dry ice can seem complex, but UPS is here to help with the information you need, plus custom solutions for dry ice shipping across your supply chain. For example, there are various UPS Temperature True options for healthcare shippers who need cold chain solutions. Customers can buy specialized packaging, as well as get advice on which solutions will work best for their product, shipping mode and time in transit.
It’s crucial to arrive at the right shipping method and duration for dry ice shipping, says Van den Bossche. “For risk mitigation, I will always factor in extra time for transit, especially if we are shipping healthcare products internationally, since the shipment could have a customs hold.”
Detailed preparation reduces the possibility that someone along the chain will need to open the box and add dry ice. Says Van den Bossche, “Once the product is in the box, we want to keep it closed up until final arrival.” However, UPS Proactive Response® service can assist if there is a case when a shipment requires dry ice replenishment while in transit.
Dry ice is a safe and effective way of shipping goods that need to stay frozen, if used properly and compliantly. Whatever your dry ice shipping need, UPS can help. Get your shipment on its way today.
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