72-Hour Dry Ice Shipping: Define the Exposure Before Testing

“72-hour dry ice pack” is a proposed shipping duration, not an inherent coolant rating. A three-day claim needs evidence that the actual product stays within its limits in the complete packout. Include the real dispatch-to-receipt exposure and credible delays before choosing a test duration.

Decide what the 72 hours includes

Scheduled transit is only one part of exposure. Map the time between packing, collection, sorting, transfers, delivery and movement into suitable receiving storage. A parcel packed before pickup can begin using coolant well before its tracking record shows movement.

Set the intended duration from that operating plan. If the credible exposure exceeds three days, a test that ends at 72 hours may not cover the route. Do not add a generic percentage reserve without defining the delay scenario it is meant to cover.

Choose a candidate configuration

• Use the actual product temperature limits and freeze sensitivity.
• Specify the container and manufacturer-permitted dry-ice use.
• Record payload dimensions, mass and starting condition.
• Choose trial dry-ice form, mass and positions.
• Keep separator and closure details in the packing drawing.
• Confirm suitable gas release and carrier acceptance for the route.

Dry ice is not suitable for every vaccine, medicine or laboratory material. Follow the specific product’s instructions rather than assuming a frozen-shipping target for all sensitive goods.

Use measurements to plan the coolant

Obtain dry-ice loss observations for a representative configuration, then use them to develop a trial quantity. An average loss rate is a planning input; it is not proof that the payload remains within its limits throughout three days.

Do not scale dry ice directly from payload weight or container volume. Compare both residual coolant and the full product temperature record. See the dry ice calculation guide for the distinction between estimation and demonstrated performance.

Test the route’s demanding conditions

Include relevant seasonal exposures and permitted load variations. Place sensors at justified warm and cold product locations. Record temperature throughout the required duration, as well as changes in the layout or closure after handling.

Define acceptance criteria before the trial and investigate deviations. A trial with coolant remaining can still fail because a product location became too warm or too cold. Keep the configuration and exposure represented by the result with the duration claim.

Where applicable to US air or water shipments, 49 CFR 173.217: carbon dioxide, solid addresses gas-release packaging. Thermal performance does not replace operator acceptance.

Frequently asked questions

Does more dry ice guarantee three days?

No. It changes loading, fit and temperature distribution and must be assessed in the complete system.

Can I count weekend delays within the same claim?

Only when the operating plan and supporting exposure actually cover them.

Can the carrier refill the box automatically?

Do not assume replenishment. If it is part of the route, agree the service and controlled handling in advance.

Approve the operating instruction

Use the accepted study to specify preparation, loading, dispatch timing, monitoring and receiving actions. Review it when the route or package changes, rather than renewing a duration claim based on its name.