Sensor placement principles for mapping studies
Place sensors where product is, where risk is, and where the monitoring probe might go — and write down why.
Placement is the design decision that determines what the study can and cannot show. Three questions guide it.
Where is product?
Sensors go at product height, in the air product sees. A sensor taped to a steel rack or placed on the floor measures the rack or the floor.
Where is risk?
- Doors, loading bays and hatches.
- Evaporators, heaters, air-handling outlets and returns.
- External walls, windows, roof, ground floor.
- Top of racking (warm air) and bottom near the floor (cold air).
- Areas with poor circulation behind columns or dense storage.
Where will monitoring live?
Include the existing or intended monitoring positions so the mapping data can show how well they represent the worst-case locations. Give every sensor a unique identifier, a described location and, if possible, coordinates — the analysis needs them, and a spatial map cannot be produced without them.
Frequently asked questions
- Should mapping sensors be placed in air or in a buffer?
- For mapping, air sensors reveal the behaviour of the space. If acceptance criteria are defined for product temperature, a subset of buffered sensors can be added and the choice documented.
- Should sensors be placed near the ceiling?
- Only if product is stored there. Otherwise measure at the highest product level; a ceiling reading characterises air nobody stores product in.
References
- [1]WHO Technical Supplement 8 to TRS 961 Annex 9: Temperature mapping of storage areas (2015)
General technical guidance written against the cited sources. It is not regulatory or legal advice and does not replace the applicable standard, guideline or a qualified reviewer's judgement.
Have a question on this topic?
Ask ValiTrac AI and see the evidence and calculation behind the answer.
Ask ValiTrac AIFree calculator: MKT & logger data check
Paste logger readings and get MKT per ICH Q1A(R2) alongside min, max, mean and out-of-limit runs with durations.
Open the calculatorTemperature Mapping on ValiTrac
Analyse logger data and identify data-quality issues, statistics, hot/cold spots and excursions.
Explore mappingRelated articles
How many sensors are needed for temperature mapping?
There is no single number: sensor count follows from the geometry, the risk points and the acceptance limits of the space.
Choosing monitoring locations from mapping results
Permanent monitoring sensors go where the mapping showed the worst case — the hot spot, the cold spot and the slowest-recovering position — not where the cable is shortest.