Temperature (and humidity) mapping studies need to be performed as part of the qualification process of temperature controlled units. Humidity should be included only if humidity control is required and defined in the mapping scope. The objective of any temperature mapping study is to assess temperature uniformity and stability over time and across a 3- dimensional space.
It should be noted, however, that temperature mapping in itself will not guarantee controlled conditions without verification of the systems that support the continued use of a temperature controlled device. Thus, temperature mapping studies should be conducted during both the OQ and PQ. The qualification is performed according to the procedures described in the relevant protocol.
No definitive standard exists for the number of stand-alone temperature devices used to map a three dimensional space, however, the study must meet the original chamber design intent by demonstrating 3-dimensional uniformity/compliance with GxP requirements. The number and location of humidity devices should be defined in an identical manner and based on thermodynamic considerations it is usually possible to utilize a smaller number of devices than for temperature. It is up to the qualification team to prepare and document a suitable approach and science-based rationale for the study.
It is recommended to assess a 3-dimensional temperature profile by selecting points at three vertical levels within a facility (ground level, mid height and high level). Additionally, points within the unit should be selected where it is known that products will be stored and where high heat/cool loads will be present or where temperature extremes may be seen (e.g. near the door or windows). Additionally a reference sensor recording ambient (external) temperature and humidity should be utilized for the duration of all qualification studies.
It is recommended that a “>50% Load” temperature study is performed during PQ. It is acceptable to either use test material / product or actual commercial (real) material for the PQ test. The rationale for use of either test or commercial material should be documented. In the event of the use of test material then the test material should have a similar thermal load to that of the anticipated commercial material.
The requirement for seasonal mapping should be documented during the risk assessment. Consideration should be given to the external temperature conditions and their effect on the chamber. For example, a chamber with an external wall will see external temperature variation from the coldest winter day to the hottest summer day and must have both summer and winter mappings completed.
In contrast, a chamber located in a country with minimal climatic temperature differences between the Summer and Winter season or one located in the centre of a building which itself is temperature controlled and with no external temperature influences will see only very slight external temperature variations during the calendar year. Consequently, summer and winter mapping will not be required.
© Temperature Technologies. All Right Reserved
