The removal of thermal cargo covers unnecessarily or prematurely during pharma transportation has been identified as a common occurrence according to DuPont, manufacturer of the Tyvek range of cargo covers. This is often due to a misunderstanding as to their function and can lead to serious temperature excursions.

In recent years, thermal cargo covers have become an essential part of a pharmaceutical shipper’s temperature-management arsenal as the industry strives to comply with increasingly onerous EU, FDA and other mandatory GDP requirements around the world. However, like all temperature management solutions, thermal covers must be used correctly.

In some cases, the misuse of cargo covers can create performance problems as Yves Le Minor, Business development Manager for DuPont Tyvek cargo covers explains: “Breathable, reflective cargo covers work extremely well in protecting pharmaceutical merchandise from the temperature surges that typically result from the solar exposures that occur on the airport tarmac and at other handover points during the shipment of pharma products. But like any passive packaging solution, cargo covers must be used correctly and they should not be removed until they reach their final destination.”

Le Minor cautions that If cargo covers have to be removed prior to arrival at the final destination then the removal must take place in a controlled environment in which the temperature is appropriate for the products concerned. “And, if cover removal is absolutely essential, then any product exposure must be for the shortest period possible with the cover being replaced and secured exactly as before.”

DuPont is addressing this issue by providing more explicit user instructions and by affixing a permanent warning message to all Tyvek cargo covers. This will take the form of a tape which will completely surround the product for maximum visibility. The cautionary legend advises against cover removal before the protected product reaches its final destination and will be presented in written, symbolic and pictogram forms. 

Greenhouse effect
DuPont have also seen many instances of Tyvek covers being covered with transparent stretch-wrap materials. Again Le Minor points out that this is not best practice. “We appreciate that stretch-wrap can be a cheap and secure means of stabilising pallets. However the Tyvek covers should be applied after any such unitisation has been carried out,” Le Minor asserts before going on to say that all strapping, wrapping and stabilising should be carried out before applying the Tyvek cover: “The application of the Tyvek cover should always be the last action prior to applying the cargo restraining net.”

Le Minor also confirms that using Tyvek negates the need for any additional weather protection: “Putting clear stretch-wrap and other films on top of Tyvek for rain protection to some extent defeats the object of the exercise,” he adds. “There is no need to add additional rain protection since, despite being breathable, Tyvek has a hydrostatic head of more than 1000mm which is more than sufficient to keep out the wettest tropical storm. Protection from surface water and splashes can be gained by using the optional Tyvek base cover which also provides further thermal benefit.”

While Tyvek covers will still provide a benefit when covered by stretch-wrap materials, the full benefit can only be realised when the cover is not encapsulated by another material. This is due to the adverse ‘greenhouse’ effects of plastic films and the fact that they are completely impermeable. “The greenhouse effect is probably the single biggest cause of unwelcome temperature excursions,” says Le Minor. “The stifling temperatures you get when you enter a greenhouse, or a car for that matter, on a hot, sunny,  day, is exactly what a pharma product experiences when it is enclosed in a stretch-wrap layer. The resulting inner temperatures can be as high as 70 degrees C or more which is way beyond the safe temperature range for many pharma products.”