Maybe.

If you are transporting by road to the UK, or the goods will reach a temperature controlled environment within 48 hours of leaving a temperature controlled location, then this blog is for you.

Thermal pallet covers

There are many different types of thermal pallet covers with different performance levels.

These typically completely enclose a palletised load with a thermal barrier as shown below.

The illustration below shows a base sheet which is placed on the pallet before boxes are stacked on top. This is sealed to the pallet cover to give a complete thermal barrier.

We will discuss the different types of thermal covers and there respective effectiveness later on.

THERMAL ENERGY

This blog explains thermal energy in more detail: https://www.cargo-wise.co.uk/blog/how-do-we-keep-things-cool-and-warm.

However, to summarise, thermal energy is transferred in three different ways.

1. Conduction is the process of heat transfer from one particle of matter to another without the movement of the particles themselves. It occurs when two objects at different temperatures are in direct contact with each other.

2. Convection involves the movement of warm particles to another location. It is the main form of heat transfer in fluids (liquids and gases). As a fluid is heated, the particles gain energy and move faster, which usually makes the fluid less dense. This less-dense fluid will then rise, and colder, denser fluid will sink to replace it, creating a convection current.

3. Radiation is heat transfer by electromagnetic waves. Unlike conduction and convection, it doesn't need a medium (like a solid material or fluid) to transfer energy. It's why we feel the heat from the sun, despite the vast, empty space in between.

A thermal barrier prevents or slows the heat transfer. In the same way that water always flows from high to low, thermal energy will always flow from high to low temperatures.

So what causes temperature increases?

In the context of transporting temperature sensitive goods by road, the main source of thermal energy is direct sunlight, summer or winter.

There are always periods of time when goods are exposed to sunlight, during loading and unloading, and invariably goods are left outside for longer than planned.

This can result in expensive damage to the goods. This includes chocolate, pizza dough, candles, confectionary, meat and dairy products etc.

High ambient temperatures will also cause a temperature increase in goods. This will be particularly true in the summer and especially the temperature inside delivery vehicles will be high.

When shipping by air freight, goods are left on the runway areas for lengthy periods (called tarmac time) and hence exposed to sunlight. 

PROTECTING YOUR TEMPERATURE SENSITIVE GOODS

There are several situations that we have come across where goods need thermal protection.

1. The time that goods spend outside a temperature controlled environment when refrigerated transport and storage are being used to transport temperature sensitive goods.

2. preventing goods getting too cold. As an example we have a customer who uses a delivery vehicle that is half frozen and half chilled. It is cheaper for them to have a full freezer vehicle and protect the chilled goods with thermal foil covers to prevent them getting too cold.

3. A customer was hiring a temperature controlled delivery vehicle to deliver only one pallet of chilled goods.

Alternatives to temperature controlled distribution

There are different types of thermal covers with subtle differences.

To simplify we will look at two types:

• Double sided foil cover
• Fibre fill foil cover

Double sided foil cover

This cover consists of five layers. the MET PET is metallised polyester, which is a more reflective and more robust alternative to foil. The LDPE provides extra durability to the MET PET, and the NON WOVEN material prevents any thermal energy being conducted through. The MET PET reflects around 95% of radiated thermal energy. So a very small amount of thermal energy reaches through the inner surface of the foil cover. 

As you will be aware (if you live in a country that uses radiators to heat houses) that the best colour to paint a radiator is matt black as this will radiate the most heat.

That follows that a shiny foil lined radiator will hardly give off any heat at all.

So this principle works with this foil cover as the foil inner liner will radiate very little heat that makes it through the cover.

These covers are usually supplied with a base sheet manufactured from the same material as the cover. This has self seal tape to secure the base sheet to cover and ensue the maximum effectiveness of the thermal cover.

Fibre filled foil covers

These covers are reusable having no base sheet, and and due to its multi layer construction is approximately twice as effective as the double sided foil cover in slowing heat transfer.

The covers have Velcro style fastening on each corner making them easy to apply and remove for storage and re-use.

Ideal for frozen goods and if you are using your own transport and can get the covers returned for use again.

As an example, a customer used these covers to keep ice frozen at a pop up bar, at a music festival in the summer,  for 5 days.

Gel ice packs

in addition to using thermal pallet covers, gel ice packs can be used to help maintain low temperatures.

An alternative is using Phase Change Material (PCM) which is designed to freeze at different temperatures.

This allows us to stabilise temperatures above zero degrees Celsius if required or below zero.

This blog explains about PCM https://www.cargo-wise.co.uk/blog/latent-energy-why-does-ice-remain-at-the-same-temperature-while-it-melts.

The science behind phase change allows us to keep products at the right temperature for longer.

Temperature data loggers

In order to ascertain the effectiveness of the thermal protection data loggers can be placed within the palletised load to record the temperature for up to 90 days.

The data is downloaded onto a PC using the data logger USB function, and the temperature checked for the duration of the transportation.

Summary

It is worth trialling some foil covers if you are finding that your cold chain transport costs are too high.

We will be happy to help you facilitate this by supplying product samples. We will guide you based on our experience.

CONTACT US FOR HELP https://www.cargo-wise.co.uk/contact-us