How to make a temperature mapping of your refrigerators and freezers

Easily map your refrigeration equipment using this temperature mapping template.

When new equipment is being put into use or when temperature monitoring is implemented, it is important to know how the equipment is performing. All refrigeration equipment will have hot and cold zones which are important to be aware of when placing temperature sensitive goods in the cooling equipment. A temperature mapping can help you spot these.

Overall mapping should be used as a tool to give you an overview of your equipment and to prove to authorities and auditors that your equipment is working properly in those areas where critical goods are placed.

This guide covers a simple method which can be used for most types of refrigerators and freezers.

What is mapping?

Mapping of refrigeration equipment is the process that is carried out to prove that the equipment meets the criteria set for the equipment and to find any hot and cold zones.

Inside a refrigerator the temperature can vary from point to point. A regular consumer refrigerator in your kitchen will in many cases show that temperature in the top of the fridge is 5 degrees higher than in the bottom. This is the main reason for performing a mapping study before taking new cooling equipment into use. The mapping can sometimes tell if some areas are either too hot or cold to be used. 

After you have mapped the equipment, you will have a clear idea of ​​how the equipment meets temperature requirements, and which zones in the equipment can be used for storage and which cannot. Last but not least, it will give you a good idea of ​​where to place your temperature monitoring equipment to get the best picture of the temperature of the critical goods.

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How is it performed?

Mapping refrigeration equipment does not have to be complicated or time consuming. The most important thing is that the scope and complexity fit the equipment and the frame in which the equipment is included. You therefore don’t need to overdo the mapping if your processes does not require it.

The most important elements of mapping are:

  • Create a plan for the mapping
  • Check the documentation of the measuring equipment
  • Setup your measuring equipment
  • Collect data
  • Document and evaluate results

1. Create a plan

Before mapping takes place, you must specify how to map, for example by making a temperature mapping standard operating procedure (SOP):

  • How many places do you want to measure?
  • Should the equipment contain goods during the mapping?
  • What are your acceptance criteria – i.e. what are the external limits for temperatures in the equipment?
  • What kind of temperature mapping equipment will you use?

The most important thing before you start the process is to find out what your limits are so you have something to validate against, as well as how thoroughly you expect to do the mapping.

2. Check the documentation of the measuring equipment

You must check that the measurement equipment you use for mapping is calibrated and comes with a certificate showing that the equipment is calibrated within a reasonable limit and timespan. Typically, 0.5C precision and a maximum calibration interval of 1 year will be enough.

Additionally, make sure you can extract data when you have completed the mapping, e.g. by using a system where you can export reports within specific time periods.

3. Set up your measuring equipment

Typically, the mapping will take place in the areas of the refrigeration equipment where high temperature fluctuations are expected. This will usually be:

  • The front door far from the cooling element
  • Close to the compressor at the bottom
  • At the back panel where the cooling elements are located.

You can save time by assessing where the largest fluctuations will occur. You will never be able to find all extremes in the refrigeration equipment, so it is more important to choose locations that are representative.

Optimally, you have several pieces of measuring equipment, that you can install at the same time. If you have only have a few or a single piece, you can instead move it around and thus create an overview of the temperature extremes in the equipment.

Typically it will be enough to measure in a 24 hours time span. This ensures that you catch both hot times in the middle of the day as well as the normal cooling cycle that the cooling equipment goes through.

To get a good picture of how your equipment performs under normal conditions, you can fill up the equipment with goods. The mapping can also run without goods, but it will not provide a precise picture of how your equipment behaves under normal conditions. 

During the mapping it is important not to open the doors of the equipment as this may affect the measurements.

4. Collect data

Whether you use multiple pieces of equipment or few that you move around, data must be collected and compared. If the goal of the mapping is to provide a credible picture of how your equipment is performing, it is important that the entire measurement period is included.

5. Document and evaluate results

When you’re done, it’s time to draw some conclusions based on the data.

Typically, the hottest and coldest areas will be of interest since the risk of deviations during normal use are high at these areas. If there are areas that are found to be unsuitable for temperature sensitive items, it may be a good idea to mark these with tape so the staff knows they cannot use them. At the same time note which areas are within the limits and thus can be used for storing critical goods.

Sometimes it may be apparent that the cooling equipment must be adjusted after which you have to perform a new mapping study.

The data gathered from the mapping can also be used to show where it is advantageous to place temperature monitoring in normal operation. If the cooling equipment turns out to have a zone where there are large fluctuations, this location can be used for temperature monitoring as this will give an early warning if the equipment malfunctions.

It is especially advantageous to use a temperature monitoring system with an alarm function, that notifies you if the equipment fails or does not work properly. This way deviations can be captured in time which will save valuable goods.

Need help?

Eupry optimises how organisations monitor, and document temperatures. Using the Internet of Things (IoT), Eupry changes the way organisations approach compliance, quality, and efficiency. We have a wide variety of customers in several sectors. If you have any questions regarding how to secure temperature sensitive goods, you are welcome to contact us.