Why Is Dry Ice Used in Packaging?

Why Is Dry Ice Used in Packaging?

The solid form of carbon dioxide is called dry ice. Dry ice is a colorless, odorless gas, while dry ice is its solid form; both have the same chemical formula as carbon dioxide.

Dry ice, often called a "miracle potion," has a wide range of uses. In logistics, it's used in packaging to preserve frozen foods, especially during transportation when other refrigeration systems or devices are unavailable.

What is Dry Ice?

Many temperature-sensitive pharmaceuticals and biological samples are packaged using dry ice during transportation. Dry ice is non-toxic and helps maintain the cold chain during the transportation of these materials. Unlike ice made from frozen water, dry ice does not leave any wet spots on the packaging.

Dry ice is a solid form of carbon dioxide, primarily used as a refrigerant. It's used to maintain a constant temperature for medical supplies, food, and other items during transport. It can also be used to freeze cargo when mechanical refrigeration isn't available.

Dry ice can be extremely dangerous if handled improperly. The extremely low temperatures can cause skin burns, and the gas can explode if not properly vented. Dry ice has many benefits , but it only works when used under the right conditions.

Because dry ice can reach extremely low temperatures, reaching -78.5°C (-109.3°F), it's primarily used for products that require freezing or refrigeration, such as frozen foods. Even for foods, dry ice may be overkill for products that don't require complete freezing, so it can be combined with ice packs.

Properties of Dry Ice

Before discussing its use in preserving temperature-sensitive materials, let's review some of its key properties.

Dry ice is colorless, odorless, and non-flammable. Its surface temperature is extremely low, at -78.5°C (-109.2°F).

At normal atmospheric pressure, dry ice changes directly from a solid to a gas at temperatures below -78.5°C. This process is called sublimation. Its extremely low sublimation temperature makes it an ideal coolant for packaging. However, this same property also makes it dangerous to humans if handled improperly.

Handling Dry Ice

Prolonged, unprotected exposure to dry ice, especially in confined spaces, can cause hypercapnia, a sudden increase in blood carbon dioxide levels. If left untreated, hypercapnia can lead to respiratory failure, convulsions, and even death.

Packaging Dry Ice

If improperly handled, dry ice can cause severe burns to the skin, similar to those caused by severe frostbite. Dry ice is typically stored in insulated boxes, either in block or pellet form. Handling dry ice requires extreme caution and should only be done in well-ventilated rooms. Vehicles transporting dry ice or packages containing dry ice must be well-ventilated to prevent the accumulation of carbon dioxide.

People handling dry ice must wear heat-insulated gloves, a face shield, and goggles. They must also receive proper training in handling dry ice and its packaging. Furthermore, dry ice must be kept out of the reach of children.

Dry Ice Container Labeling

In most countries, dry ice is classified as a dangerous material and has the UN 1845 dangerous goods number. Any container containing dry ice must be labeled Class 9 (Miscellaneous Dangerous Goods).

Transport operators must comply with various standards and regulations when packaging goods with dry ice (whether by road, air, or sea).

Goods packaged with dry ice must be clearly marked (UN 1845) and labeled to indicate that they contain dry ice. The packaging must be sturdy enough to withstand any damage during transportation and handling. The bill of lading must indicate "Dry Ice. Class 9. UN 1845," along with the number of containers containing dry ice and the net weight of the dry ice used (in kilograms).

How is dry ice made?

Dry ice is produced through a simple and therefore inexpensive process. Carbon dioxide gas is first liquefied and then frozen at -78.5°C (-109°F). It is then compressed into a solid state and cut into blocks or pellets as needed. Large blocks can be cut using a gas saw.

Dry Ice Marking

In most cases, the carbon dioxide used to make dry ice is a byproduct of ammonia refining. Natural gas is burned to separate carbon and hydrogen atoms. The hydrogen mixes with nitrogen to produce ammonia, while the remaining carbon mixes with oxygen to produce carbon dioxide.

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Carbon dioxide is also a byproduct of ethanol production.

Dry ice is often tightly packed with insulation board or paper to slow sublimation.

Food-Grade Dry Ice

Sometimes, regular dry ice may not be suitable for preserving certain medications or foods. The carbon dioxide used to make food-grade dry ice undergoes a process called desorption.

During this process, the carbon dioxide passes through a chamber containing a carbon dioxide absorbent. During the desorption process, any other gases are removed, leaving only clean carbon dioxide.

The carbon dioxide is then liquefied, frozen, and compressed into large blocks. Afterwards, it is cut into the desired size. In logistics and transportation, this process is known as "purging."

Packing Goods with Dry Ice

For best results, use expanded polystyrene (EPS) foam boxes and corrugated cardboard boxes to transport temperature-sensitive goods. Sometimes, Styrofoam is used instead of EPS.

Place the temperature-sensitive goods in an expanded polystyrene (EPS) (or Styrofoam) box filled with dry ice. Then, secure the box and place it inside a slightly larger, sturdier corrugated cardboard box. Then, fill the space between the two.

Extreme care must be taken to ensure that the box is not tightly closed or sealed. Carbon dioxide produced during sublimation can cause pressure to build up inside a tightly sealed box, potentially causing it to burst.

Generally speaking, at extremely low temperatures of -78.5°C, 10 kg of dry ice in a well-insulated box will last for 40 to 50 hours unless opened during this time. However, this depends greatly on the type and packaging method.

To ensure optimal results, high-quality packaging materials should be used.

What other uses does dry ice have?

Besides refrigeration, dry ice has other uses. Let's take a look at some of them.

Dry ice is used in the soft drink and ice cream industries. It's also used for decorations to prevent ice from melting and for smoke effects in theaters.

When dry ice is used in sealed containers, it can deter certain pests, such as insects. It's also used for pest control, such as rodents, and for certain types of insect bait.

Dry ice has many other industrial uses, the most important of which is a process called sandblasting. In this process, dry ice pellets are forced through a nozzle using an air compressor to remove various residues, such as paint, glue, oil, mold, etc., from mechanical equipment.

The discovery of dry ice is attributed to French inventor Adrien Jean-Pierre Thilorier in 1835. In 1925, his invention was patented and trademarked in the United States , and he began commercializing it, particularly for refrigeration applications.

How to Ship Dry Ice?

Precautions must be taken when handling dry ice to ensure safety. Wear safety goggles, an apron to protect your body and clothing, and special gloves to prevent burns. Anyone handling dry ice in the supply chain should receive training. Packaging dry ice requires special care as it can be hazardous. Good ventilation is essential. As carbon dioxide sublimates, its pressure increases, potentially causing explosions and asphyxiation.

Shipping dry ice requires multiple layers of special packaging to ensure safe transport. Food must be shipped between dry ice blocks in an insulated container. The insulation must be made of some type of polystyrene foam, as it is strong, resists deformation, and provides physical protection during transport. The insulated box containing dry ice must be placed inside an outer corrugated cardboard box.

Not all of these layers should be sealed, as this could be hazardous. (These steps are for reference only, not instructions.)

Dry ice shipments must be labeled on the outside with a label stating "Dry Ice" or "Solid Carbon Dioxide" and the weight of the dry ice.