EPS Containers
EPS (Expanded Polystyrene) is a cost-effective solution for many temperature-sensitive shipments. EPS is often called "styrofoam", but this is a reference to the company Styrofoam® and it is incorrect to refer to any EPS container by this misnomer. This is similar to using trade names from Rollerblade® and Kleenex®. Many in the industry call EPS containers "coolers" to differentiate them from other types of containers. EPS containers are rightly considered the workhorse of the industry and account for as much as 80% of the temperature-controlled shipments annually. Manufacturing can produce many varieties of containers in all sizes. EPS generally has an R-value between 3.5 and 5, depending on the density and size of the EPS bead used, but it is a little known fact that the R-value of EPS is slightly higher at colder temperatures than at room temperature.
Molded vs. 6-panel EPS Containers:
Some in the industry will claim that the thermal performance of a well-made 6-panel EPS container is the same as a molded EPS container and in some regards, they are correct. Sitting in a test chamber, undisturbed, a tight-fitting 6-panel EPS container may perform equally well as a similarly sized molded container. However, this idyllic setting is not realistic when you consider the hazards of shipping. The hazards facing parcel packages as they navigate through the distribution system are well-known within the shipping industry. Vibration from track beds and shocks from being dropped are commonly recorded by test shipments. Thermal testing within an environmental chamber will not take into account these hazards. Would you expect a 6-panel EPS container to perform well thermally after being dropped three times from 16"? With one corner drop, sizable gaps can develop between the EPS panels, resulting in a dramatic reduction of R-value. Since most companies cannot guarantee their parcels won't be dropped at some point during the shipment, they prefer the peace-of-mind that comes from a quality molded EPS container.
Advantages:
•Lower Cost - EPS has a significantly lower cost than many other insulating materials. For example, a 1" wall EPS container could cost as little as a third of the price of a 1" wall PUR container of equivalent size. However, beware that you get what you pay for. There are many ways to save money in EPS manufacturing, most notably by reducing the density (and therefore the thermal and protective properties) of the container. Be sure to set density specifications for each container and ask for a certificate of compliance for each shipment to assure the correct density has been used.
•Less Weight - EPS can weigh less than many other options. For example, a 1" wall EPS container with outer dimensions of 12" x 12" x 14" with a 1.5 pounds per square inch density would weigh approximately 3.5 pounds. A comparable PUR container could weigh as much as 9 pounds.
•Mass Production - EPS containers can be produced in mass quantities using multi-cavity tools. A tool may product one container (called a "one-up" tool) or up to eight containers (called an "eight-up" tool). This ability to manufacture large numbers of containers helps keep the cost of EPS containers low. However, it is important not to confuse EPS containers with a commodity. If the EPS containers are to be used for temperature-sensitive shipments in a regulated industry, it is important to assure the quality of the containers is guaranteed. One way of assuring this is asking for a COC (certificate of compliance) for each delivery.
•Recyclable - EPS containers are often considered environmentally-friendly because of their ability to be recycled. Used EPS containers can be ground down to their expanded EPS beads and reformed. Be sure to test the thermal property differences between new and recycled EPS containers before accepting recycled containers from your manufacturer.
•Outer Corrugate - Molded EPS containers are often shipped in an external corrugate RSC, protecting them from the potential damages of the distribution system. If there is no damage to the EPS container, it could be reused simply by replacing the outer corrugate.
Disadvantages:
•Low R-value - EPS has a lower R-value than PUR containers and will be less effective in preventing outside temperatures from affecting the temperature-sensitive product load. The R-value of EPS is between 3.5 and 5.0 and varies based on density. Once the density exceeds 2.2 pounds per square inch, the R-value does not increase considerably and the container becomes more fragile. Ultimately, a reduction in insulation R-value from using EPS containers may require an increase in phase-change material.
•Higher Fragility - Molded EPS containers can crack and separate during shipment if overloaded with weight from product and refrigerant. This is a problem rarely encountered in PUR containers and can be prevented through a combination of solutions. A higher density of EPS can be specified, or a double-wall outer corrugate shell can be included to buffer and drop shock. Distribution testing using a standard test series (ISTA 1A or 2A, for example) should be performed to assure that the container and more importantly, the product, is not damaged by shipping hazards. Compression and drop testing are good indicators of whether a container can handle the rigors of the distribution cycles.
•Quality Control - For larger EPS containers, it is not difficult for a supplier to stamp a lot number directly onto the container. However, smaller EPS containers may not be linked except through the incoming documents from the shipper.
•High Tool Cost - If a custom container is desired, the cost associated with building a new tool can be substantial. Depending on the complexity of the design, an EPS tool could cost anywhere from ,000 to ,000.
•Reduced Reusability - EPS containers are not as reusable as many of the other container materials. EPS was traditionally designed to be a single-use shipper that can be recycled, but not reused. However, with more intricate tools and sturdier containers, coupled with corporations promoting reusability, many EPS containers are now multi-use. There are many distribution options that can assist in protecting the integrity of the packaging. First and foremost is a corrugate overwrap that can be replaced when necessary at a cheaper price than a new container. The corrugate will take the majority of the distribution system wear and tear including taping and scuffing from conveyer belts. A properly fitted corrugate overwrap can help protect the outside of an EPS container, but it is equally important to protect the inside. Much of the internal damage for EPS shippers comes from refrigerant leakage or condensation and from product movement. Refrigerant, especially gel packs or bags of wet ice, can leak and cause damage if not contained. This can be reduced by properly designing the shipping configuration such that there is adequate room for each component. Compressed gel packs due to a tight configuration will have a much higher tendency to burst during transit. Another source of liquid damage in shipping can come from cold refrigerant developing condensation on the gel film or plastic bag. This can be reduced by spending extra for gel packs with special condensation-reducing film, or by adding a simple plastic liner to the container before packing.
PUR Containers
PUR (Polyurethane) is a highly effective solution for many temperature-sensitive shipments. PUR containers are less frequently utilized because of their cost, but the insulation value of PUR is much higher than that of EPS. Small manufacturing sites can produce many varieties of container sizes.
Advantages:
•High R-Value - The insulation value of PUR is much higher than that of EPS and can be used to hold tighter temperature ranges for longer periods of time. The EPS insulation is more effective in preventing the outside (ambient) temperature from affecting the product. This increase in insulation value can effectively reduce the amount of refrigerant weight required.
•High Quality - Due to their increased price, many PUR containers are individually inspected for quality after production. This is an increase in quality over EPS containers, which are produced so quickly that individual containers cannot effectively be inspected. Some PUR containers have individual barcodes or QC stamps to show lot numbers and approvals.
•Rigid - PUR containers can withstand thousands of pounds of pressure without any noticeable deflection. The strength of the containers allow them to be stacked high without worry about product damage.
•Smaller size - The increased R-value allows for less refrigerant to be used to thermally protect the product, therefore potentially reducing the overall size of the insulated container needed.
•Inexpensive tool cost - PUR tools are relatively inexpensive and are single-container tools. Each tool may cost only ,000 to ,000, much less than the tens of thousands of dollars for EPS containers.
•Reusability - In certain distribution settings, PUR containers can be used for multiple shipments. In addition, some pallet-sized six-panel PUR containers can be incorporated into a refurbishing program that will replace damaged or missing parts as a specific step in the cycle of the container. Often the limiting factor in reusing a PUR container is the outside corrugate (which often can't be replaced) and the inside corrugate (which may get wet or damaged and may not be replaceable).
Disadvantages:
•Nonrecyclable - PUR manufacturing is a permanent chemical reaction and cannot be broken down for reuse like EPS. PUR is not recyclable, a fact that can limit its use, especially in foreign countries who have limitations on importing environmentally-unfriendly materials.
•High Cost - The cost of a PUR container is approximately four times as much as that of a comparable EPS container. This can make PUR containers cost prohibitive for many applications.
•Slow production speed - Unlike EPS containers, PUR containers are not mass-produced. Individual tools create one container at a time. For larger, thicker-walled PUR containers, a single container may sit in the mold for over 30 minutes. Obviously, multiple tools are utilized at once in order to produce dozens of containers per day. However, this is less than the hundreds of EPS containers that could be produced per day.
•Inventory space - Without the ability to break down to individual panels, PUR containers take up a large amount of inventory space in the end-user's warehouse.
•Limitations in Design - PUR manufacturing tools are limited in the intricacies of their design. Although some manufacturers have been successful in molding icustom shapes or air-circulating channels into PUR container walls, others remain with only traditionally square (or rectangular) containers.
•High weight - Due to the density of the PUR and the corrugate weight, PUR containers weigh more than a comparably-sized EPS container.
Vacuum Insulated Panel (VIP) Containers Vacuum Insulated Panel (VIP) containers have the highest insulation value of all containers available on the market for small shipments. This advantage comes at a price; VIP containers are generally the most expensive container when compared to EPS or PUR. A medium-sized VIP container could cost -, depending on the manufacturer.
It is important to point out that VIP containers on the market are not molded. They are constructed by assembling 5 vacuum insulated panels (VIPs) for the base and using the sixth panel for the lid. The base panels are often taped together to eliminate any air gaps. This extra assembly step can be included in the construction of the VIP containers because the additional labor costs can be covered by the containers' high price.
In order to protect the VIPs, manufacturers will often surround the panels with a buffer material. For example, the Insulated Shipper-VIP line from Tegrant Corporation, ThermoSafe Brands are VIP containers designed within molded EPS containers. The EPS provides a (relatively) minor insulation value, but is critical in protecting the VIPs from potential damages.
Advantages:
•High R-Value - VIP containers have the highest R-value of any containers, allowing them to resist extreme heat or extreme cold for the longest duration.
•Low weight - Because of their increased insulation value, VIP containers require less refrigerant and would weigh less than a comparably-designed PUR container. Also, VIP containers are lighter than empty PUR containers.
•Reusable - As long as the vacuum-insulated panels remain undamaged and the vacuum is not lost, VIP containers can be reused multiple times. Disadvantages:
•High Cost - The extreme cost of the VIP containers often make them a luxury of low volume high-cost products.
•Breakage - The effectiveness of a VIP container is drastically reduced once the vacuum is lost in any of the panels. Considering the high cost of the container and assuming the value of the product is also high, VIP containers can be a risky choice. This is especially true if you consider the hazards present in the distribution system, where dropping and vibration are commonplace. As mentioned above, manufacturers often include extra materials, like an EPS barrier, to help protect the VIPs from damage.
•Availability - Fewer manufacturers offer VIP containers than EPS or PUR. This can VIP containers risky to depend on for frequent shipments. Also, few manufacturers of VIP containers actually manufacture the vacuum panels themselves, generally they purchase them from another company. This can create an additional level of risk if the secondary supplier decides to stop selling the panels, which has happened to manufacturers in the past.
Active Containers 'Active containers' is a general term given to any shipping container that does not rely solely on the internal thermodynamics of the packaging materials to regulate the temperatures of the payload. This is contrary to "passive" containers, or those already mentioned such as EPS, PUR and VIP containers. These passive containers use refrigerants (such as gel packs) to keep product temperatures within the desired criteria. The natural thermodynamics of the system created at packout control the product temperatures. Active containers may use electricity, often in the form of batteries, to regulate temperatures.
The most well-known active container is produced by Envirotainer, where a large LD3 container is custom-equipped with a dry ice bunker and product space for one pallet. Batteries are used to operate a thermostat on the outside of the container. This thermostat turns a fan within the container on or off, depending on the air temperature needed to maintain the required product temperature. There are few manufacturers of active containers, but they are highly effective in holding product temperatures within tight temperature ranges when used correctly.
Advantages:
•Automated Thermostat - Container can automatically detect that product temperatures are too warm or too cold and can adjust the internal container temperature.
•Ease of Packout - Many active containers require no packout; simply place the product load into the space provided, close the container and send. Preparation may be needed before the container is packed, however, such as recharging the battery or loading new batteries. Loading dry ice is also simpler and faster than arranging dozens of gel packs. Where did dry ice come in?
•Payload Size - Because there is no need to include gel packs or other refrigerants, active containers often have a larger payload area for product than passive systems. This means more temperature-sensitive material can be shipped per container, which should be considered when evaluating the total cost of the packaging.
•Reusable - Active containers are always made to be reused multiple times. They often contain more metal than any other insulated containers used for shipping temperature-sensitive products. Is that a good thing?
•Lease options - Some manufacturers choose to lease active containers, a benefit since it requires little up-front capital. Disadvantages:
•High Cost - Leasing active containers is often negotiated on a daily fee. The time to receive the container, pack the container, ship the container and have it arrive at the destination can be considerable.
•Availability - Active containers that are leased may not always be available for your shipment or may be expensive to obtain in less-populated areas. For shipments with little advance warning, this type of solution may be less desirable than passive containers that can be stored in your warehouse.
•Battery Life - An inherent problem with active containers is their ability to continue working for long periods of time. At some point, the source of energy (such as batteries) will be exhausted and the container will lose its ability to hold product temperatures within criteria. Some active containers only advertise 48 or 72 hours of shipping duration, to ensure the container remains energized for the entire shipment.
•Winter Shipping - A notorious issue with active containers over the last 5 years is their inability to prevent payload temperatures from falling below the 2-8°C range if the environment surrounding the container is cold. Without a heating element, the active container is unable to prevent product temperatures from getting too cold. However, this problem has been addressed in some of the new products recently unveiled by active container manufacturers like Envirotainers. Newer models include a heating coil to keep product temperatures warmer, including a new battery system to ensure this increased drain on energy will not reduce the available time for the shipment.
•Validation - Many companies who use active containers have a difficult time validating their system since they may not know which version or which model may arrive if the company leases.
•Manufacturer Risk - There are only a few manufacturers of active containers, increasing the risk not being able to ship. Having a contingency plan if a packaging supplier has issues might be impossible, and is much more likely with passive materials where multiple companies manufacture similar items.
•Cleanliness - Active containers that are leased by a company may not be fully cleaned after the last user's shipment. This may not be bad, flu vaccines that smell like bananas might be the next big hit!
