Cold-chain freight (revision 5)
Old revision·21:10, 23 Nov 2024·MelanocortinMil
| Cold-chain freight | |
|---|---|
| Passive systems | Insulation plus phase-change material |
| Active systems | Powered refrigeration |
| Evidence of performance | A temperature record, not a cold pack |
| Topic infobox · conventions | |
Cold-chain freight is transport under controlled temperature. For peptides it is used to limit the degradation routes — deamidation, oxidation, aggregation — whose rates rise with temperature, and its performance is a matter of record rather than of appearance.[1]
A passive shipper is insulation plus a phase-change material, designed to hold a temperature range for a stated duration under a stated ambient profile. It does not hold indefinitely, and a shipment that takes longer than the design duration is outside the qualification whatever the pack looks like on arrival.[2]
The presence of a cold pack is therefore not evidence that a cold chain was maintained. The evidence is a temperature record, from a logger or an indicator, covering the whole of transit. See Temperature excursion.[2]
Passive and active systems
[edit]Passive shippers are qualified by testing against defined ambient profiles: a summer profile, a winter profile, and a duration. Qualification states what the system will do under those conditions, and nothing about what it will do outside them.[2]
The coolant matters. Gel packs conditioned to refrigerator temperature hold a chilled range; frozen packs can take contents below the intended range, and freezing is a distinct hazard for a solution. Phase-change materials formulated to melt at the target temperature avoid both extremes.
Active systems maintain temperature by refrigeration and can hold it as long as they are powered. They are used for high-value or long-duration shipments and are uncommon in research-chemical supply.[1]