A specification needs containment written as carefully as temperature. For Category B (UN 3373) specimens the packaging is three nested layers: a leakproof primary tube, a leakproof secondary receptacle and a rigid outer carrier; with liquids, absorbent enough for the entire contents goes between the tube and the secondary receptacle. Written as separate lines, the bidder knows which layer is being sold; a single line reading specimen transport bag creates price differences.
- Temperature: the narrowest regime on the laboratory's test list becomes the acceptance criterion.
- Absorbent: write capacity, not a count, sufficient for the maximum liquid volume carried. A clause written as a number of sheets becomes void when the tube volume changes.
- Durability: the primary or secondary receptacle withstands 95 kPa internal pressure without leaking, and the filled package comes through a 1.2 m drop without leakage. Ask the supplier for this test record for the chosen tube and volume.
- Layout: tubes stay upright, the coolant never touches the specimen, the inner surface is non-porous and resistant to disinfectant.
- Records: a pocket for the data logger and a sleeve for the handover form.
Pre-acceptance validation is done on the institution's longest route; carriers are chosen with short distances in mind and then the furthest site starts using the same one. Wash frequency is written in too, for example resistance to five disinfections a week.
