Ice packs come in two types: sealed packs that are filled at the factory, and containers made for the user to fill. A sealed pack is never opened and never topped up with water; getting it ready again simply means freezing it. In a refillable container the liquid, amount and closure method come from the model instructions, and the fill line is never exceeded, because water expands as it freezes.
Classify the product first
Check the model code, label and instructions. A sealed, prefilled container is not opened to replace its contents or top up a loss, and a punctured or leaking sealed pack is not taped up but taken out of use. If the shell, seam, cap or filling description does not match the model instructions, do not start filling.
| Identity question | Filling decision |
|---|---|
| Is it sealed and prefilled? | Do not open it; follow the model procedure |
| Does the model define it as refillable? | Use only the specified medium, amount and method |
| Is there a cap but no instruction? | A cap does not count as permission to fill; stop |
| Are identity or contents unknown? | Add no water, salt or other substance; segregate it |
Checklist for a refillable model. For a refillable model, the medium, level, closure method, freezer orientation and readiness criterion all come from the same instruction. After closing the cap, turn the container upside down for a few minutes: if the seal has not seated, the leak shows here. A permanent mark showing which solution went into a refilled container stops packs with different melting points getting mixed up.
| Record field | What to record |
|---|---|
| Model and instruction version | Model code and instruction/revision number |
| Approved filling medium | The medium named in the instruction |
| Quantity and unit | The instructed level, volume or mass unit |
| Closure check | Cap, gasket or seam check result |
| Preparation | Freezer orientation, rack layout and model acceptance |
Why is there no universal fill percentage?
Water becomes less dense and occupies more volume as it freezes; USGS explains water density, including the effect of dissolved substances. A safe fill level depends on the container design and its contents, which is why the fill line on the container sets the limit. No salt, antifreeze or gel is added unless the instruction names it: a home-made mix leaves the melting point unknown.
Freezing layout
The container is frozen in the orientation the instruction asks for and in a layout that keeps airflow open. For GEBHARDT eutectic plates the freezing temperature is at least 5 °C below the plate's melting point, an air gap is left between plates, and the filling must be fully solid before use.
Keep filling and preparation records separate: first medium, amount and closure check, then freezing conditions and readiness check. For GEBHARDT plate preparation, see the GEBHARDT technical document, and for freezing steps the ice-pack preparation guide.
