Temperature mapping of storage areas
The purpose of a temperature mapping study is to document and control the temperature distribution within a storage area.
Temperature mapping of storage areas is a systematic mapping procedure in any cold room, freezer room, or another temperature-controlled store.
This guideline does not cover the mapping of small-scale cold chain equipment such as refrigerators or freezers.
The following Technical Supplements are also relevant:
Checking the accuracy of temperature control and monitoring devices.
Qualification of temperature-controlled road vehicles.
Qualification of temperature-controlled storage areas.
Temperature and humidity monitoring systems for transport operations.
All new temperature-controlled storage areas must be temperature-mapped as part of a fully documented verification process before the installation is commissioned and handed over by the installer
The temperature mapping procedures should:
demonstrate the air temperature profile throughout the storage area, when empty and in a normal loaded condition;
define zones that should not be used for storage of TTSPPs (for example areas in close proximity to cooling coils, cold airstreams, or heat sources).
if required, demonstrate the time taken for temperatures to exceed the designated limits in the event of a power failure Depending upon the routine monitoring strategy, subsequent mapping exercises may also be required periodically – for example, every three years – in order to demonstrate continuing compliance fixed monitors provide continuous data and a periodic re-evaluation that assesses all aspects of system performance since the initial mapping may be more appropriate.
Re-mapping may be justified whenever analysis of temperature and/or humidity monitoring records shows unexplained variability outside normal operating limits
A temperature-mapping exercise is required for any space allocated for the storage and handling of products with a specified labeled storage temperature. This includes freezer rooms, cold rooms, temperature-controlled storage areas, quarantine areas, and receiving and loading bays, and may also include laboratories.
The permitted temperature ranges in these areas will vary – for example, −25.0 °C to −10.0 °C, 2.0 °C to 8.0 °C, or 15.0 °C to 25.0 °C.
A mapping study establishes the temperature distribution within the zone being mapped and locates hot and cold spots.
The temperature-mapping process has four stages:
a. Prepare a mapping protocol.
b. Carry out the mapping exercise.
c. Prepare a mapping report.
d. Implement the recommendations by carrying out the remedial and other actions identified in the mapping report. A follow-up mapping exercise may then be needed to verify the effectiveness of the remedial actions.
A mapping operation requires a sufficient number of electronic data logging monitors (EDLMs) to ensure that the temperature distribution in the space to be mapped is adequately characterized.
The selected EDLMs must:
be technically suitable for the specific mapping task and for the intended operating environment.
provide a reliable and continuous record of time-temperature data.
have an appropriate temperature range so that all anticipated temperature extremes can be recorded (e.g. from −30 °C to +60 °C).
have a user-programmable data sampling period, allowing time intervals to be set in the range from 1 minute to 15 minutes (maximum) and sufficient memory for the intended length of the study and the chosen recording interval.
have a US National Institute of Standards and Technology (NIST)- traceable 3-point calibration certificate with a guaranteed error of no more than ± 0.5 °C at each calibration point.
enable the recorded time-temperature data to be downloaded to a computer system for subsequent analysis.
have data storage and analytical software that complies with applicable regulatory requirements (for example 21 CFR part 11).
Reference: Temperature mapping of storage areas (WHO Technical Report Series, No. 961, 2011, Annex 9)