The job of a cold chain carrier specification is to make incoming bids comparable. Neither material name nor wall thickness does that; the description of the work does: how many litres of product, for how many hours, with what outside temperature, held within what range. A specification written without those lines brings back bids that resemble nothing in common, and procurement can only look at price.
Load, duration, ambient conditions and the internal target together define what the cold chain is.
| Field | Information to specify | Example |
|---|---|---|
| Load | Product type, net volume and mass, inner packaging, loading pattern | 40 litres net, packed in crates |
| Duration | Time from preparation to recipient storage, waiting and lid-opening plan | 8 hours after the lid closes |
| Ambient | Season, sun and shade, vehicle or depot environment, delay scenario | 30 °C ambient, out of direct sun |
| Internal target | Permitted product range and acceptance criterion | 2 to 8 °C at product core |
The most common mistake is writing the target so that it is measured in the air inside the container. Air changes within seconds each time the lid opens, while the core of the product holds its temperature for hours. If the acceptance criterion is set at the product core, a supplier cannot pass on an air reading. State the product, fill level and starting temperature of the sample load as well.
Usable volume is what remains after inner packaging, coolant and required gaps are subtracted. A container that does not fit the pallet layout carries dead volume on every trip; instead of an external size, write how many containers must fit on a Euro pallet, and add the loaded mass and handles.
Either define the coolant yourself (type, quantity, preparation, placement) or leave it wholly to the supplier. Wording between the two causes trouble, because if you set the number of plates you also own the result. Write preparation according to the chosen coolant: GEBHARDT eutectic plates are used fully frozen, frozen at least 5 °C below their melting point, and freezing takes 8 to 24 hours depending on the cooling method. That time is plate preparation; how many hours the packed load lasts is shown by a separate test.
| Unmeasurable wording | Measurable equivalent |
|---|---|
| Shall be highly insulated | At 30 °C ambient, product core shall not exceed 8 °C after 8 hours |
| Shall be of robust construction | Shall stack three high when full, with no permanent deformation of the bottom unit |
| Shall be easy to clean | No weld gaps or sharp internal corners, washable with hot water |
| Food-grade material | A food-contact declaration of conformity shall be submitted with the bid |
The weakest part of the insulation is the lid perimeter; the specification should state latch type, whether the gasket is replaceable and how spare gaskets are supplied.
Ask for these with the bid:
- Test report: which model, load, coolant layout and starting temperature, how many hours, measured where
- Records of preparation, loading, lid openings and waiting
- Food-contact declaration of conformity and the model it covers
- Cleaning and maintenance instructions
- Spare parts list and warranty scope (body, gasket and castors separate)
If the inputs differ, do not compare results as one score. Requesting a sample before evaluation is the cheapest insurance in the document: it runs for a day with your own product on your route. One favourable trial does not establish performance across every operating condition.
The acceptance decision is written into the specification too: who reviews the result, what happens on an excursion and the basis for the decision. FAO's HACCP monitoring guidance covers method, frequency and records; its corrective-action guidance covers excursions and affected product.
