Temperature Mapping
Temperature Mapping is performed to determine if a storage area can maintain temperature within defined limits (Fridges, Freezers, Rooms, Warehouses and Incubators etc.). Sensors are distributed throughout the unit/room in pre-defined locations to confirm it performs within pre-defined set points.
The storage area is further challenged with additional tests such as empty mapping, loaded mapping, door open, power failure, pull down tests, fan failure etc. which are all performed to demonstrate the unit controls within pre-defined parameters and to determine the position of permanent monitoring/alarm probes.
The storage area is further challenged with additional tests such as empty mapping, loaded mapping, door open, power failure, pull down tests, fan failure etc. which are all performed to demonstrate the unit controls within pre-defined parameters and to determine the position of permanent monitoring/alarm probes.
We provide flexible training in Temperature Mapping and Thermal Validation. To find out more click here.
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We offer temperature and humidity mapping services for warehouses, controlled temperature storage, cold stores and freezer rooms. to find out more click here.
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We specialise in thermal validation and temperature mapping. If you would like to know more about how we can help, please click here.
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What set point should we use?
The table below lists some common laboratory instruments and their set points:
These temperature set-points are used as an initial guide, however if temperature mapping demonstrates a more suitable set-point for the range then the set point can be adjusted (e.g. 31.9°C instead of 32.5°C may provide a more uniform temperature within the specified limits due to the location of the control probe). |
What tests should we perform during Temperature Mapping?
For temperature controlled units such as fridges, freezers and incubators, the testing required should be identified during risk assessment.
Examples of common tests performed include:
Additional tests that may be performed if required for the product or process:
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For some storage environments, for example warehouses, it may not be possible to perform some of the testing for example an empty distribution map, power off or door open. There may also be additional testing requirements specifically for that environment which could include:
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How long should we map for?
The duration of temperature map should show the stability of the unit and identify any routine changes within the use for example a defrost cycle. Your site may already have a Validation Master Plan (VMP) or procedure with the mapping durations detailed. The table below shows some typical examples for temperature mapping durations:
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For warehouses it is important to consider the movement of people, fans, doors opening and closing, seasonal variations. It is important to consider the impact of these variations including changes in shift patterns or the week and weekend. It is also important to understand the temperature distribution during seasonal variations by performing winter and summer maps.
How many sensors should we use for temperature mapping?
The number of sensors required really depends on the type of unit being tested and what it will be used for. Some common examples of number of sensors can be found below:
Fridges, Freezers and Incubators (Temperature Controlled Units)
Cold Stores – based on a risk assessment which would consider:
Warehouse – based on a risk assessment which would consider:
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Where should we place our sensors?
Sensors should be distributed throughout the storage area to get a detailed understanding of the performance of the unit. To identify cold/hot spots within the unit/area and determine locations for the permanent monitoring probe/s. If this is a requalification exercise a sensor should be placed adjacent to the monitoring/alarm probe/s. This is to ensure that this location is the most suitable for the monitoring probe i.e. the Highest or Lowest temperature within the unit. A common mistake is to place the monitoring probe in the location closest to the averarge temperature within the unit. This is the location least likely to fail, this would mean that any fault with the system is unlikely to be detected until the next requalification exercise. We recommend that two monitoring/alarm probes are placed within a temperature controlled unit. These probes should be located in the minimum and the maximum temperature locations identified during the temperature map. This will help identify any faults with high and low temperatures on the unit. Monitoring probes may be placed in suitable buffers (Glycol, aluminium block etc) or with alarm delays to prevent regular alarms caused by routine use (door opening etc.) |
Should we be mapping humidity?We perform humidity mapping on storage areas that contain product which may be impacted by a change in humidity, stability cabinets and humidity chambers.
Humidity should form a part of the risk assessment to determine if monitoring and mapping is required. When performing humidity mapping it is important to ensure the humidity data loggers are calibrated for the range you are testing. |
What data logger should we use for temperature mapping?
Data logger cost varies from around £7 up to several thousand pounds, the quality differences between these loggers is substantial. The quality and accuracy of the loggers increase with the cost and some loggers are not suitable for certain applications. Some important considerations are:
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Our data loggers page details our data logging systems and what we use them for. The sensors you choose should fit the process you’re looking to perform testing on. Whilst a high end data logger may meet the requirements for response time in an autoclave it is not ideally suited to temperature mapping a warehouse, which may require hundreds of sensors.
The data logger software is often overlooked when purchasing new sensors. Suitable software can offer substantial time savings in data processing, data review and quality assurance approvals. At Thermal Compliance even with our most cost efficient data loggers we use high end software to provide clear and compliant reports. Data loggers expedite the process of temperature mapping and suitable software expedites the documentation, reporting and review stages.
The data logger software is often overlooked when purchasing new sensors. Suitable software can offer substantial time savings in data processing, data review and quality assurance approvals. At Thermal Compliance even with our most cost efficient data loggers we use high end software to provide clear and compliant reports. Data loggers expedite the process of temperature mapping and suitable software expedites the documentation, reporting and review stages.
Calibration of Data loggers
Data loggers should be calibrated annually either by a ISO 17025 Calibration Laboratory (UKAS, NIST, DANAK etc) or be traceable to national standards. Some consideration should be given to how the sensors can be calibrated for example internal sensors will need to be placed in a chamber or in a fluids bath. External sensors can be placed in dry or fluids baths and therefore are easier to calibrate onsite.
In addition to annual calibrations we perform calibration verifications on our sensors. We do this by placing the sensors in a calibration bath adjacent to ISO 17025 traceable probe (IRTD-400, ETS-25, Fluke 1524). This is to ensure that the calibration loop is closed for the sensors used. This provides a verification of the sensors in case of damage etc. Some manufacturers allow for data loggers to be calibrated in the same way as thermocouples. Sensors are placed in a calibration bath with a temperature reference probe (calibrated to ISO 17025) and then an automatic calibration is performed with offsets applied. |
If you would like assistance with your temperature mapping requirements please contact us or visit our temperature mapping page for further information.
Free Monthly Validation WebinarsValidation Workshop is a Free monthly webinar focussed on Validation Issues.
If you would like to know more about our upcoming webinars please join our LinkedIn group www.linkedin.com/groups/13987418/ You can access all the previous validation workshops at www.thermalcompliance.com |