From the Outside In: Using Coolants to Maintain Temperature

You can have a great box, a sturdy cooler, but without the proper coolant in the shipment, your product stands little chance against the element. After implementing packaging tips referenced in earlier blog posts [insert links] to prevent damage, temperature control must be considered. If the temperature of your perishable product is not properly maintained, you risk spoilage, a shorter shelf life, decreased value, and a loss of business. To achieve the proper temperature, the coolant must be integrated into your packaging.

Perform testing to make sure you have enough coolant for the specific conditions your packaging undergoes. On average, the ratio should be between 15 percent and 40 percent; however, the amount necessary will vary based on the type of product you are shipping, the type of coolant you are using (gel packs or dry ice) what the ambient temperatures are during the shipping process, and more.

The ratio of coolant to product depends on many conditions, including the type of product, the anticipated ambient temperature, weather, and other factors.  Because of these considerations, it may be necessary to increase the amount of coolant used for a particular shipment.  Recommended coolant ratios range from 15% to 40% depending on expected weather conditions, refrigerant method (dry ice or gel packs) and product shipped.

Net/Gross Coolant Formula

 When calculating the true cost to ship your product, you should take into consideration certain factors to help you determine the net cost per pound to ship, particularly the weight of the coolant and the packaging.

For example, a 20-pound box of tuna may require 4 pounds of coolant, as determined by the 20% ratio.  With the packaging used weighing 1 pound, the total weight of the package is now 25 pounds, which will be used to calculate the price to ship the package, $65.00 (sample price).

To determine how much it costs per pound on the net to ship that product, the following formula can be used:

Price to ship package/weight of product = net cost per pound to ship product

Look to use the Coolant Formula when you are determining the true cost per pound to ship your product, excluding coolant and packaging weight.  Increasing or decreasing the amount of coolant will affect the cost per pound to ship your product.  More information is available in our Packaging Tips or on the PeriShip Customer Portal.

Shipping with Gel Packs

Gel packs are a great foundation for creating a cold internal temperature.  Gel packs can be cost-effective, reusable, and come in a variety of shapes and sizes. We encourage all gel packs to be frozen on a flat surface at a consistent temperature of -10° F for a minimum of 48 hours (preferably longer).

If concerned with condensation build up and damage to your packaging or product, consider condensation-resistant gel packs that have a fabric liner intended to absorb and prevent condensation build-up.

Also, when possible, use a larger gel pack in place of two smaller gel packs.  The larger mass allows it to thaw slower than smaller massed gel packs, thus helping to maintain internal temperatures for a longer period of time.

Shipping with Dry Ice

Dry ice (or carbon dioxide solid, UN 1845) is considered a dangerous good/hazardous material for air transport and requires special handling.  Shippers are also required to have function-specific dangerous goods training as outlined in 49CFR (Code of Federal Regulations) 172.700.

A Dry Ice label such as this one much be placed on the outside of the box prior to shipping. Failure to do so can lead to potential monetary fines.

When dry ice changes to carbon dioxide gas in enclosed spaces like aircraft cargo holds, it displaces oxygen.  The design and construction of packaging that is used for dry ice shipments must prevent the buildup of pressure that could cause rupturing.  Dry ice must never be placed in an airtight container.

When shipping with dry ice, you must provide correct identification, classification, markings, and labeling on your outer carton to comply with current requirements in the International Air Transport Association (IATA) dangerous goods regulations.

The following permanent markings are required on the outer packaging of all IATA dry ice shipments:

  • “Dry Ice” or “Carbon Dioxide Solid”
  • “UN 1845”
  • Net weight of dry ice in kilograms
  • Name and address of the shipper
  • Name and address of the recipient

Keep in mind that as the package transits and time passes the dry ice will start to sublimate, get smaller, and thus may take up less room in the package.  If the dry ice is supporting the product in any way be aware that the support will lessen over time.

It is important to ensure that you pack your products with enough coolant to maintain the proper temperature throughout the transit time.  It is highly recommended to pack your products with enough coolant or insulation to maintain temperature for one extra transit day.

These perishable packaging tips are just the beginning! Stay tuned for further details regarding each of these steps so that you can make sure your product will arrive fresh and undamaged. To further ensure the last mile makes the right impression, contact PeriShip to learn about our perishable product shipping and logistics services.

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