The objective of temperature monitoring is the assurance to the end user that the stored goods are being maintained in the specified controlled environment. Accurate monitoring begins with a calibrated probe. Most often, this is accomplished through an ILAC / ISO certified facility with traceability to a NIST standard. Certification is only a first step of many that will result the assurance of the accuracy of the system.
This series of articles will address many of those components that should be considered when temperature monitoring is concerned. Considerations that will be explored in this series will be:
· Probe calibration / certification
· Temperature probe selection
· Probe placement
· Sampling interval
· Alert timing
· Probe buffering
As stated above, the first step is a calibrated / verified accurate temperature. The specific requirements for each application may vary depending on the governing body for the individual industry. For example, vaccine storage is regulated by the CDC (Center for Disease Control and Prevention). Within their guidance, the requirement for calibration is covered under ISO / ILAC 17025. The goal of this process is to ensure the measurement probe can represent accurately the temperature of the storage unit. This is particularly important when the storage unit is refrigerated (frozen) using a compressor, also known as a Carnot heat engine. An exception to the need for NIST traceable calibration would be cryogenic storage monitoring. Liquid Nitrogen (LN2) monitoring is governed by physics. The temperature of the LN2 will be minus 197.6 deg Centigrade consistently.
The need for calibration and calibration interval is often determined by the industry segment and the temperature probe supplier. It is important to have available copies of the Calibration Certificates at the time of an audit or inspection. The PharmaWatch solution makes available these certificates on the display portal.