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‘Zero excursion’ in cold chain an almost achievable reality says Sofrigam
Rueil-Malmaison, France: – Temperature-controlled logistics and pharmaceutical cold chain specialist Sofrigam SA says the ideal of ‘zero excursions’ – products remaining 100% within specified temperature limits – is not quite an unrealistic pipe dream.
Following specific research and analysis, Sofrigam is able to show that, while temperature excursions in cold-chain storage and shipping may never actually be eliminated completely, they can be reduced to insignificant levels given the right preparations.
Eutectic or PCM?
Sofrigam has published an article on its website that delivers the main findings of research based on analysis of thousands of actual temperature recordings to analyse the main causes of temperature excursions and the actions to be implemented to avoid them.
It shows that the main temperature ranges where excursions occur are +2/+8 °C and +15/+25 °C where products must stay within both upper and lower limits. Policing these zones requires careful selection of cooling media, with a clear choice to be made between phase change materials (PCMs) and water-based eutectic plates, largely dependent on their latent heat and melting temperatures.
Water based eutectic solutions offer high latent heat at temperatures of 0°C or below at lower cost, used for products to be maintained between +2 °C and +8 °C, with a dual or even triple packout configuration, depending on season. The main difficulties are managing mid-seasons and switching from one configuration to another. Single configuration eutectics can be used for logistics circuits characterized by a hot profile with possible very short segments.
PCMs are typically used for +2/+8 °C, +15/+25 °C and for other temperature ranges above 0 °C. They offer a latent heat lower than that of water at temperatures more closely adapted to products, at higher cost. This solution can be used with a dual configuration summer and winter or with single configuration. In universal configuration, PCM plates are usually frozen then increase their temperature and placed around products (on all six sides). In some cases, they are stabilized at a temperature close to +5 °C without reaching freezing. Either way, the solution takes up more volume because thermal storage is reduced.
Avoiding unplanned freezing
By choosing an adapted melting temperature, water based eutectic solutions allow products to be kept frozen with single configurations. Dry ice can also maintain frozen products at very low temperatures.
The thermal storage capacity is mainly ensured by the latent phase. Whatever the material, the sensitive phase cannot provide sufficient performance to meet real needs. With a melting temperature of 0 °C, water based eutectic solutions can only be correctly frozen below -10 °C.
PCMs used for products at +2/+8 °C, have melting temperatures between +3 °C and +7 °C. Solidifying these PCMs requires use of refrigerated room set at temperature close to 0 °C or standard freezers set to operate above their normal temperature of between 0 °C and -18 °C. PCMs can be stabilized between +2 °C and +5 °C but their performance will be reduced.
Temperature excursions and their position in the logistics circuit are determined, allowing the identification of the logistics steps and the associated environment. In a continuous improvement approach, rigorous analysis allows evaluation of the compatibility of the qualified configuration with actual profiles, revealing suitable solutions. Excursions are classified according to their nature (below +2 °C or above +8 °C) and placed at the logistic step where they occurred: pre-departure, during transport and post-arrival.
Excursions can be caused by any of the following:
- Preparation of the configuration elements
- Preparation and et configuration of the logger
- Incorrect loading of carton
- Means of transport (refrigerated vehicle or not, aircraft…)
- Intermediate storage (customs, transfer, etc.)
- Reception and unpacking at arrival.
Crucially, 60% of excursions are recorded at the beginning of journey and 30% after arrival, meaning that some 90% of cases are due to preparation or unpacking errors and therefore avoidable.
Excursions below +2 °C are typically recorded for configurations that use frozen eutectic plates. They occur initially when the boxes are stored in the cold room after loading and in some cases in mid-chain as a result of an unplanned intermediate storage at +5 °C or transport by refrigerated truck.
Excursions above +8 °C are mainly recorded for configurations using eutectic plates or PCMs stabilized at +5 °C. Such configurations require careful preparation because the cold reserve is very low and any excess of +8 °C at the beginning causes the same type of excursions in the middle and at the end of the profile.
Statistical analysis of actual readings shows that real-life temperature profiles are more moderate than those required in qualification tests. In most cases the hot or cold profiles required for qualification are more binding, which can complicate the solution and cause excursions.
The majority of the alarms at the beginning or at the arrival are false excursions recorded at loading ‘hot’ recorders or by removing them during unpacking while still recording. In many cases, registration is stopped several days or even several weeks after the arrival.
The Sofrigam article recommends a series of steps to avoid temperature excursions:
- Better control: The temperature-controlled chain must be managed as a whole, from establishing specifications to the use of the solution through the design and qualification. Responsibilities and acceptance criteria must be defined. This comprehensive approach optimizes performance and the total logistics cost (TCO).
- Design and qualification: Specifications for designing or choosing a temperature-controlled box must consider product temperature requirements and accepted tolerances based on stability tests. The logistics steps and associated durations must be identified, including preparation, storage, loading, transport, intermediate storage, customs, transfer and delivery areas . IT is necessary to establish risk analysis that recognizes all the parameters of the shipment.
- Pre-departure: The thermal storage media (PCM or water-based eutectics) must be prepared under suitable conditions and according to validated procedures, with minimized loading times. Frozen plates (PCM or water-based) must be loaded first, then liquid ones and finally products. For +2/+8 °C products, storage and shipping at +5 °C are favoured for configurations using unfrozen plates. The reverse must be applied for configurations with frozen plates. Data loggers must be conditioned to the temperature of the products and suitably parameterized.
- During transport: The actual logistics circuit must be identified and the configuration adapted accordingly, taking into account cold room storage, refrigerated truck transport, etc. Logistics partners and all actors need to be trained and informed.
- Post-arrival: A procedure for unpacking and stopping the loggers must be established and respected to avoid false excursions and false alarms. Stakeholders must be trained and informed.
Zero excursion reality
“An insulated box equipped with a thermal storage means is a solution designed for predefined temperature profiles. The use of PCMs and over-sizing of the solution reduce temperature excursions but cannot eradicate them. To reach zero excursion, the logistics circuit must be controlled within predefined limits of temperature and duration,” says Sofrigam.
“These conditions must be respected to ensure the reproducibility of the results. The phenomenon of temperature excursions goes beyond the sole responsibility of the insulated box to the respect of the established operating procedure and the control of the logistics steps,” the company continues.
Finally, Sofrigam cautions: “Logistics hazards are the main cause of excursions. The cold chain must be optimized as in its entirety: specifications, design of the box, pre-qualification, preparation, transport, reception. All actors in the chain need to be trained and informed to respect good practices of use of solution. They must also be involved in a continual improvement process.”
With over 40 years of experience, Sofrigam provide a comprehensive portfolio of innovative packaging and related solutions that allow pharmaceutical and other clients to optimize their temperature-controlled logistic chains.
From its French roots, Sofrigam has become a global company, operating in the USA, Canada, UK and across Europe, with manufacturing centers in North America and Europe.
Sofrigam manufactures a range of standard and made-to-measure thermal packaging products, including cartons, cases, bags and pouches that cover every step in the cool chain, from manufacturer to end-user.
It also offers customized services designed to achieve secure, cost effective and ecological cold chain logistics in shipping, storage and packaging.
Sofrigam Services accompany clients through every step of the logistics chain while prioritizing safety of goods and reducing costs. Advanced software and other solutions allow clients to audit their cold chains, monitor shipments, analyze logistics lanes, manage Inventory and optimize ordering.
Sofrigam can also deliver best Time to Market through thermal simulation equipment combined with its ‘cut & glue’ customization process that gives customers the ability to adapt any catalog product to its own needs with development time reduced to as little as 15 days.