Monitoring Probe placement

Fridges, Freezers and Incubators should be monitored to ensure them temperature conditions are maintained within the unit. To do this monitoring probes are placed within the unit and alarms activated when the unit goes out of tolerance.
The challenge arises when you need to identify the worst-case location to place your monitoring probe. If there is a single monitoring probe you may choose to place it in one of three locations:
1.       The Coldest location identified during temperature mapping.
2.       The hottest location identified during temperature mapping.
3.       The average location identified during temperature mapping.
If you choose the average temperature of the unit, you would expect the hottest/coldest location to go out of specification before the average location. It would however be the optimum position for both high and low temperature excursions using a single monitoring probe.
You may choose to place the monitoring sensor at the coldest temperature identified during temperature mapping, for a 30-35°C incubator. As the ambient temperature outside the unit is lower than inside the unit this would alarm when the door was left open or during a power failure. If there were a fan failure however and the temperature increased, this may not be identified.
We recommend that two monitoring probes are used and placed at the hottest and coldest location identified during the temperature mapping. If this is not possible we recommend performing a risk assessment to assess the potential failure and the impact on the product or materials stored within the unit. If you would like assistance with the location of your monitoring probes or performing a risk assessment, we are happy to help