Square vs. Rectangle for Time Sensitive Thermal Shipping

Jeff asks,

We had a client ask about airflow in a RSC. They are in the baby food industry and have a limited amount of time to ship product. They asked if it was better to ship square or rectangle carton? They will be using gel packs and thermal pads with plastic liners on the inside of the RSC. Baby food will go in P.E.T. jars or biodegradable trays with cornstarch liners.

A square carton always has an advantage as a single box over a rectangular one because the side walls equally share the compression load. But the design of the box may depend on the pallet configuration and how well the deck boards support the side panels and the corners of the box. Think about the whole system.

I assume they are concerned about the degradation (warming up) of the gel packs. If the box is securely packed, and properly sealed then airflow inside the box should not be an issue regardless of the shape. If they are shipping single boxes, other than the strength of the box it should have little or no adverse affect on the temperature of the contents regardless of shape.

If they are shipping pallet sized orders, then again you must consider the entire system. Square boxes can be stacked so there is basically no air space between them. Therefore, only the outer most surfaces of the boxes on a pallet are exposed to direct airflow and any warming or cooling caused by airflow. The inner boxes and inner sides of the outer boxes on the pallet are insulated from direct flow.

If a rectangular box is designed so they are equal to two square boxes, that is exactly twice as long as they are wide, and the pallet is of the size to allow them to be packed as a solid cube, then it would be no different than stacking a cube of square boxes. However, if the rectangular box doesn’t allow for a tight cube pallet pack, or if it requires a chimney type stack or other irregular stack on the pallet, then you will have more surface area will be exposed to the atmosphere and you will lose some of the insulating properties of a solid stack.

– Ralph

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