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CONSIDERATIONS FOR THE SUCCESSFUL SHIPPING OF PERISHABLE MATERIALS
Whether the product is a food, pharmaceutical, chemical, biological substance, or even a live organism, a great number of factors need to be considered in order to arrive at a reliable method for shipping perishables.
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> The type of material being shipped
> The thermal mass the product itself holds
> Dead air pockets within a payload's packaging
> Viable temperature range of product
> Temperature state of product placed in container
> Sensitivity to temperature incursions
> Product value ratio to justifiable shipping costs
> Tradeoffs between expedited and extended transit
> Package weight vs. dim weight factors
> Regional, Domestic, or International
> Factoring for multiple destination climate conditions
> Seasonal or multi season shipping protocols
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Though perishable cargos and shipping requirements can vary greatly, there are often a number of commonalities within each product category. Through years of experience, our staff can generally offer advice on commonly successful packaging and shipping strategies to match nearly any situation. However, for highly sensitive and unusual products, or those with more stringent time and temperature requirements, our TESTING AND VALIDATION services may prove to be necessary and invaluable.
RECOMMENDATIONS ON WHEN AND HOW TO USE ICE PACKS
Ice packs are most commonly used to maintain refrigerated temperatures, but may also be employed to help keep materials frozen, or even to keep products from freezing.
For non-frozen payloads, the most common method of shipping with ice packs is to place them above the product. This is often ideal for larger volume payloads such as master cartons of medications, home infusion materials, processed meats and cheeses, and even tropical fish. Since cold air flows downward, top loading the ice also offers the most even distribution of refrigeration throughout the time of transport. However, condensation of thawing ice sitting on top of moisture sensitive product and packaging can be a real concern. For this reason Plastilite also offers MAG PACKS (moisture absorbing gel packs) to limit potential damages.
Top loading with ice packs is also the most common means of extending the shipping life of frozen products when dry ice is not an option. In this position the ice packs can act as a shield to fend off the affects of heat at the most vulnerable area within a shipping container.
In other instances, products such as vaccine vials with especially low mass can be extremely sensitive to freezing, or need to stay within a narrow non-frozen temperature window. These conditions can demand a variety pf packaging modifications be employed in order find a workable solution.
One method to prevent product from freezing can be to simply precondition ice packs to a less extreme temperature before using. Even though freezer settings can vary greatly, the frozen state of water-based ice packs is only self-sustainable at, or near, 0C (32F). Often simple exposure of ice packs for a sufficient period at room temperature is all that is necessary to reduce a freezing risk. This technique, however, does cause ice packs to burn off some of their initial thermal energy, which in turn can shorten their life.
Another approach can be to adjust placement of ice packs to beneath, around, or even totally surrounding a payload to reach a desired effect. Keep in mind that cold air does not readily flow upwards and that the positioning of ice below a payload can result in the top layers of a payload being exposed to significantly higher temperatures in transit. This is especially true in larger shipping containers.
Buffering the payload from the coolant with a layer of corrugated or bubble wrap can also be effective, as can the addition of non-frozen ice packs as payload ballast to moderate the severity, as well as speed, of temperature changes.
Extending shipping life to take advantage of lower freight rates is often a balancing act between better packaging and greater amounts of ice. These choices can in turn increase parcel weights, dimensional weights, or risk of freezing. One highly effective option, with little down side, is the use of Plastilite's THERMALAST insulative liner bags within EPS foam coolers.
With all the possible variables, establishing a shipping protocol can be intimidating. An experienced Plastilite representative can offer direction on how to deal with these and other issues to help create viable and sustainable methods of shipping your products using ice packs.
See THERMA-FROST for more information on ice pack types, sizes, and uses.
RECOMMENDATIONS ON WHEN AND HOW TO USE DRY ICE
When readily available, dry ice is generally the preferred coolant used to maintain payloads in a frozen state. At -78.5C (-109.3F) it can be very effective, though like all things, it is important to understand the limitations. The rate in which dry ice sublimates depends on a number of factors that will in turn determine realistic shipping time expectations.
Locally sourced dry ice may be available as snow, pellets, or blocks. For duration, consider that snow and pellets, though perhaps easier to work with, have significantly more surface area, which in turn increases their sublimation rate. Block ice can be sometimes be cumbersome to handle, or only accessible in dimensions that will not work within your optimal shipping carton size.
Dry Ice On Top 
DRY ICE ON TOP OF PRODUCT EXPOSED TO MORE HEAT, BUT TENDS TO KEEP PAYLOAD EVENLY FROZEN
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Dry Ice On Bottom 
DRY ICE BENEATH PRODUCTS SUBLIMATES SLOWER BUT MAY FAIL TO KEEP ENTIRE PAYLOAD FROZEN
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In addition to type, overall effectiveness of dry ice can be significantly impacted by the quality of the container, shipping conditions, and placement. Positioning ice underneath a payload can effectively delay sublimation by limiting surface contact with air. Though the ice may last substantially longer in this manner, the cold may find it hard to access the upper reaches of the payload, leaving that area exposed to heat. This is especially a concern in larger shipping containers.
Placing the ice on top will generally cause the ice to sublimate faster, but since the cold is more evenly dispersed throughout the compartment, the entire payload may actually stay frozen longer. Center or side packing of the ice can also be a workable compromise though payload shifting once the ice is gone should be considered.
Regardless of placement, limiting dead air space, and using just a single block of ice will normally achieve best results. THERMALAST liner bags can also be used to stretch out the life of the ice and keep products frozen longer once the ice is spent.
Since dry ice is treated as a hazardous substance by the Department of Transportation is always a good idea to consult with the intended parcel carrier to discuss proper documentation and labeling requirements before shipping.
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