Whoever reads the log later should find five answers on every line: where, when, with which instrument, what temperature and, if it was out of range, what was done. The example below shows two lines from a frozen store room with a target of -18 °C or colder.
| Time | Point and instrument | Reading | Note | Deviation and action | By |
|---|---|---|---|---|---|
| 07:30 | D1-S, rack above door, TK-03 | -19.5 °C | - | - | A.Y. |
| 16:10 | D1-S, rack above door, TK-03 | -15.5 °C | Loading, door open 12 min | Door closed, area cleared; 16:40 recheck: -18.4 °C | A.Y. |
- Take the point codes from the mapping study. Mapping a loaded room with many loggers shows the warmest and coldest spots; the permanent measuring points are those two plus one that represents the average.
- Put one reading in the busiest dispatch hour. A reading taken in the calm of the morning makes the log look good every day and never shows the problem.
- Write the defrost times at the top of the form. A high reading that falls in that window is explained in the Note column and is not confused with a real excursion.
- On a deviation, keep the reading, the action and the recheck on the same line. If the recheck has not returned to target, the product status and the person responsible are added too.
- At the weekly review the reviewer dates and signs; where a continuous logger runs, the name of its data file goes on the form.
The logger records the temperature; the person filling in the form records what happened: a door left open, pallets stacked in front of the evaporator. That is why the form hangs next to the measuring point, since a form kept in the office gets filled in without anyone walking to the point.