What we have written on the cold chain57 / 154

A box can fit the aisle and still not open. The space needed follows from the door width measured from the hinge axis and from the opening angle.

A leaking gel pack stops the shipment. Goods, gel pack and transport box each get a separate decision: the goods decision rests on the safety data sheet, the box decision on the cleaning record.

Before choosing a route, measure stops, door openings, product requirements and plate-charging energy.

A gel pack laid flat in a single layer freezes through in 24-48 hours. A pack that is hard outside can still be soft in the middle; readiness is judged at the centre.

In 1718 ice cream was made with salted ice, and in 1724 Fahrenheit marked the zero of his thermometer with a salt and ice mixture. Today's eutectic plate uses the same physics in a sealed body.

A pack that stays soft may be unfrozen, or frozen but still flexible. The glycol content and the freezing time tell the two apart.

The word grows from Greek roots meaning to melt well, and it entered chemistry through Frederick Guthrie's 1884 paper. Below are the figures behind the definition, and how the melting point of a GEBHARDT plate sets its freezing temperature.

The gel pack temperature class, freezing time, the cooling capacity of a 500 g pack and how many packs a warm load needs.

Check test method, conditions, instrument traceability and report scope, not just the centre name.

Gel, water, eutectic plates and instant cold packs do not do the same job. Melting point, container fit and preparation flow decide the choice.

Robot use alone is not proof of quality; compare the same part against drawings and acceptance records.

Reusable gel packs are mostly water and propylene glycol, and minor contact causes mild irritation. Instant cold packs are the type that needs care; a leaking pack and the goods it touched are set aside.