Plate count is often found by applying a ratio to container volume; that works by chance on short rounds and fails on long ones. A plate absorbs heat while changing phase at its melting point: the heat load entering the container sets how long it keeps absorbing.
The heat load has three parts: heat leaking through the container surface, warm air entering at every lid opening and the excess heat the product carries when loaded. The third is often forgotten: product that has waited on the dock and warmed up gives the plate a cooling job on top of the holding job.
| Round | Duration | Stops | Plate requirement |
|---|---|---|---|
| Dense city | 4 hours | 10 | High, many openings |
| Sparse city | 4 hours | 4 | Medium |
| Long rural | 8 hours | 6 | High, long duration |
GEBHARDT states that cooling time depends on the product, the fill level and pre-cooling, and that frequent or long lid openings affect the temperature. Put a logger in the container and follow the round for a few days: if the last stop sits well below target there is too much plate, and if it sits close to the limit there is too little.
