Sudden rises or falls in temperature can have dire consequences for medical products in transit or storage. Thermal blankets are increasingly being touted as a cost-effective means of guarding against this, and their proponents have academic research on their side.
Melissa Germain and Jean-Pierre Emond, cold chain technology researchers at Georgia Tech Research Institute, released a 2013 paper on heat-transfer principles, the effects of environmental temperatures, and the purpose of packaging components that gave blankets the thumbs-up, and it is generally accepted that a fitted sheet wrapped around a pallet of goods can be a useful component in a cold chain.
As the technique is still relatively new, however, creating an effective, complete system that combines thermal blankets with other temperature maintenance measures still throws up a range of issues.
Comparing and qualifying
In the US, regulators now look for documentation that controlled room temperature (CRT) products, as well as refrigerated items, have been protected from temperature spikes, and thermal insulated pallet covers are widely seen as a cost-effective means of ensuring compliance. Higher-end designs are made from the most versatile insulation materials on the market, which reflect up to 97% of heat transferred via radiation (from the sun, for example), and trap the same percentage of cold air in the space around the product.
The environments in which sensitive products are transported must also be temperature controlled. Active or passive cooling systems may be used, but these are expensive and are vulnerable to breakdowns or equipment malfunctions.
Most packaging for cold chain goods already comes wrapped in temperature-sensitive materials, but as the Georgia Tech study notes, “Many packages use metalised foil along with a small insulator, such as bubble wrap, as part of the thermal protection system.
The foil is perceived as a reflective material that would reduce the incoming heat caused by radiation. These foils, however, are highly conductive materials that transfer the energy more quickly to the inside of the package.”
The cheaper option is therefore essentially useless, and could even be conducive to damaging temperature fluctuations.
Layers of complexity
There are several sorts of blanket, each with its own set of specific attributes, and advantanges and disadvantages to the cold chain. Thin covers, for example, are usually inexpensive, feature just one layer and are designed for single trips. These are primarily used to reflect direct sunlight and tend to be supplied in preformed sizes.
The next category up are thicker, often multilayered and more expensive, but made with repeat use and closed loop operations in mind. They are designed to provide higher protection against convection temperature threat (such as hot air rising off tarmac) and are usually preformed.
Space age insulation
Shrouds are another option: these are single or multilayered rectangles designed to lie over the goods. The largest type, the quilt, is like a blanket, but uses diamond-patterned stitching that helps to maximise insulation.
Many blanket manufacturers use a technique originally developed by the US space programme that works on the vacuum-flask principle, whereby two reflective surfaces are separated by a non-conductive space. These two surfaces provide a vapour barrier that helps to regulate humidity.
Such products are generally easy to apply and provide a secure fit. They are also usually reusuable, lightweight and moisture and humidity-resistant, all of which up adds to overall cost-effectiveness.
The only exception to this may be the rolls of silver-backed bubble wrap, which can often take two people up to 20 minutes to place on a pallet when not preformed.
One often overlooked blanket bonus is that they enable the carrying of mixed loads of varying temperatures and reduce cross-contamination. Laced-on coverings also help to deter pilfering by cloaking the cargo, thereby concealing its nature. This makes stealing to order much more difficult, as well as drawing immediate attention to any tampering that might indicate missing goods.
Consistently useful
Blankets are one of the ways in which consistent product temperatures can be maintained at every stage of a cold chain supply network, including transport by air, sea or road, as well as warehouse storage. Many companies now use insulation to protect valuable cargo from summer heat gain and winter heat loss no matter where in the world it’s being transported to, and most firms will work with pharma producers to develop bespoke strategies for meeting supply chain challenges.
Many new blankets are designed – and heavily advertised – as being up to a fifth of the weight of conventional cargo quilts and thermal covers, as well as being made from using non-toxic, recyclable materials.
Most such products available from mainstream stockists provide prequalified solutions for chilled (2–8 °C) and controlled room temperature (15–25°C) shipments of 3–2,990L.
These can be very cost-effective, as the extra petrol use associated with refrigerated or heated trucks is avoided.
They are also quick to install, with minimal stress for the transportation team and no need for forklift trucks or other extra transport – a boon in terms of packing and loading times.
Environmental concerns
The insulating foil blankets, thermal pallet covers and container liners are reusable many times over and do not need to be replaced until worn out or damaged.
Insulation, such as expanded polystyrene (EPS), helps reduce how much thermal energy enters or leaves a package due to the temperature differential between the inside and outside, which enables better temperature control.
Not only are the covers themselves more durable than disposables or plastic bubble wrap, they also reduce waste by providing proper insulation.
Wastage is a highly sensitive topic. Drugs that appear undamaged on the outside heading for landfill are not only a problem for those looking to break even financially, but also a PR disaster for pharma companies hoping to appear altruistic and environmentally conscious.
The negatives
Recurring problems associated with blankets often stem from mishandling by those who have not been trained to use cold-chain equipment correctly.
While most ground handling crews will prioritise temperature-sensitive freight whether it’s covered or not, one of the main issues occurs when teams confuse thermal covers for permanent protection and decide to leave pallets on the tarmac. This has been a particular problem in extremely hot places, like Dubai or Arizona, where there have been instances of under-trained crews leaving products out in the baking sun for several hours until they’ve dealt with other, more apparently time-sensitive cargo. Such treatment will invariably cause temperature fluctuations, no matter how well insulated.
Sensitive issues
There’s no doubt that, to various extents depending on grades, blankets can protect sensitive pharmaceutical cargo in transit by shielding it from extreme temperature fluctuations.
The blankets and covers also provide a measure of protection from tampering, as they are an all-round barrier, and are opaque, unlike regular plastic wrap.
But with the market now inundated with different operators offering these products, it will be up to the companies that need them to ensure that they do not fall foul of substandard or defective covers that will not deliver the safety required.
The covers may claim to be a one-fix solution for myriad issues, but whether or not they truly deliver the helping hand that cold chain needs to fight back against sea freight, and other kinds of competition, remains to be seen.