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In Cold Chain Management, refrigerants, commonly known as gel packs or cool packs, are one of the components that are the most utilized. They are crucial for keeping products around the desired temperature while in transit. Most Pharmaceutical and Food & Beverage distributors can use up to 25,000 refrigerants per week for all their shipments, making gel packs conditioning a really important part of Cold Chain activities.
What is gel pack conditioning you ask? Gel pack conditioning is the process of cooling or warming the product uniformly to a desired state and temperature by placing it inside a refrigerator or freezer (depending on the targeted conditioning temperature) for a prescribed amount of time, until it is ready to be used. This sounds fairly simple, but there are few important factors to consider for ensuring that the right temperature is reached for all the refrigerants.
Equipment Specifications, Maintenance & Compliance
Not all refrigerators and freezers are suitable for conditioning gel packs. Residential equipment are the least adequate as they have a poor temperature uniformity and were not designed for such applications. Commercial and medical grade refrigerators and freezers are the most suitable, since they were designed and tested for protecting temperature-sensitive products, hence their stability and reliability. When comes the time to choose an equipment manufacturer and model, there are three important specifications that should be considered:
Equipment Temperature Range (Operational) The temperature range should be wide enough to cover the conditioning temperatures needed while taking into account the measurement uncertainties coming from the equipment controller, your temperature monitoring sensors, and any equipment temperature mapping study results.
Equipment Controller Accuracy (±) The refrigerator or freezer controller should have a high accuracy to provide confidence in the measurement taken by the equipment and its air temperature output.
Equipment Temperature Uniformity (±) Uniformity across a refrigerator or freezer will tell you how well it can prevent temperature deviations from the top shelf to the bottom shelf. Uniformity should be as high as possible to ensure that temperatures are homogeneous across the equipment.
While temperature range, accuracy, and uniformity are important for selecting the most adequate equipment, maintenance is equally important for ensuring proper functioning over its lifecycle. Brand new refrigerators and freezers, for instance, may have a compressor-cycle refrigeration system that easily reaches and maintains desired temperatures with low variations when defrosting. This may not remain true over time when the system starts deteriorating. That is why scheduled maintenance should be completed at regular intervals to prevent equipment failure and keep it within the required state.
Finally, compliance with applicable regulations and industry standards are mandatory for storing drugs and medicine products. They ensure that equipment performances are analyzed and documented through equipment mappings, equipment qualifications, and refrigerant conditioning studies. They also ensure that deviations and non-conformance observed during studies are addressed in a timely manner, and operational risks are understood and mitigated. When combining a carefully chosen equipment with a solid preventive maintenance program and compliance appraisals, it elevates the performance output and trustworthiness of the selected equipment.
Contact Freezers
Although contact freezers are expensive, they are optimal in freezing masses uniformly and quickly. Instead of cooling through air convection, they leverage surface-to-surface contact (conduction) between the cooling elements and the mass to cool down (i.e., refrigerants). This conditioning procedure is highly recommended for packaging processes that require a quick freezing of refrigerants.
Recommendations:
Conditioning by the unit If refrigerants are conditioned by the unit inside a refrigerator or a freezer, it is recommended to place them inside a ventilated tray, with not too many refrigerant layers (one on top of each other). Ventilated trays should be placed on a shelf and should not block the air flow across the equipment. Single refrigerant conditioning is the quickest method but takes more preparation as they are handled one by one.
Conditioning by cases If refrigerants are conditioned by cases inside a refrigerator or a freezer, it is recommended to place them in a way that air flows constantly on the sides, front, and back, from the top shelf to the bottom shelf. Conditioning by cases can take between 5 to 10 complete days, depending on the refrigerant constitution, the equipment performance, and the case thickness and layout inside the equipment.
Conditioning by the skid If refrigerants are conditioned by the skid inside a walk-in cooler or freezer, it is recommended to place the skids in a way that air will keep flowing on all sides. Conditioning by the skid can take between 2 to 3 complete weeks, depending on the refrigerant constitution, the equipment performance, the skid assembly layout, and the case thickness.
IMPORTANT: Refrigerant conditioning study should always be performed to really understand how long it takes for all refrigerants to be conditioned using refrigerators and freezers.