What a continuous temperature monitoring system must do
Capture at an appropriate interval, alarm reliably, store data securely with an audit trail, and keep working through power and network failures.
WHO Technical Supplement 16 describes the design and qualification of monitoring systems for fixed storage areas. The functional requirements are simple to state: measure the right thing, in the right place, often enough; tell someone when it goes wrong; keep the record.
Requirement checklist
- Calibrated sensors with documented uncertainty and calibration interval.
- Sampling interval justified against product limits and expected excursion dynamics.
- Local buffering so data survive network outages; battery backup for power loss.
- Alarms with escalation, acknowledgement and record of response.
- Access control, audit trail, time synchronisation.
- Reports for periodic review and for excursions.
- Validated software with change control.
Qualification of the system follows IQ/OQ/PQ: installation checks, alarm and failure-mode tests, then performance under routine use.
Frequently asked questions
- Is a chart recorder still acceptable?
- It can be, if it is calibrated, records are retained and reviewed, and alarms are handled separately. Most sites have moved to electronic systems for data-integrity and review reasons.
References
- [1]WHO Technical Supplement 16 to TRS 961 Annex 9: Environmental temperature monitoring systems for fixed storage areas
- [2]EudraLex Volume 4, Annex 11: Computerised Systems
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.
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