When mapping storage areas (warehouses and trailers) for temperature sensitive items, you must consider more than just taking note of the temperature in certain areas. You must also take into consideration: dead areas, the outside temperature (such as summer and winter), and power failures (especially for trailer mapping).

Tip #1 – Keep Track of the Time

There is no specific regulatory requirement stating the appropriate amount of time to spend mapping your trailer, warehouse, or equipment.  We recommend that you map your warehouse for a minimum of 7 days. This way you cover your weekdays and weekends. The primary objective for mapping your trailer or other type of equipment is to collect the data of all the cycles of your reefer or controller.  Therefore, we recommend 24 to 48 or 72 hours.  Pay close attention to the date and time when your mapping starts; it could be when you have placed your last logger, or when they start recording if they are pre-programmed. If you have planned to do a 24 hours mapping, you must collect data for at least 24 hours. Twenty-three hours and 59 seconds is not acceptable.

Tip #2 – Place Temperature Sensors in Trouble Areas

Areas that see a lot of traffic (near entrances and exits) and areas that are subject to dips or spikes in temperature should have temperature sensors installed. Not only does this let you know when there are shifts in temperature, but it also catches these shifts in real-time. There are no regulations stating the number of loggers to be used and where to place them. We used to place them every 50ft and at different height level. Additionally, place everywhere there is a thermostat, and/or an HVAC system. It is better to place more than less.

Tip #3 – Take Note of the Temperature Empty and With a Load

A cold empty vehicle can see a significant temperature rise when it is fully loaded. Take note of the differences in temperature when it’s empty and when it’s fully or half-stocked. Usually we do the empty mapping and the full loaded in a row. We carefully note the beginning and the end of each cycle. To load equipment or a trailer, you could use artificial products or boxes.

Tip #4 – Map After a Power Down Impact 

Instead of waiting for the worst-case scenario, perform your own power down test to see what the temperature would be like without the intervention of coolers, fans, or other electronic cooling equipment. Take note of the temperature in 5-minute intervals. Take note of how quickly a vehicle takes to get back to the proper temperature as well. Two tests could be done:

  1. Turn off the reefer and see how long it takes for the temperature of the trailer to go over 8°C.
  2. Turn off the primary reefer and if there is a backup one determine if it starts automatically. (Sometimes both primary and back up work simultaneously).

The same could be done not for a warehouse, but for a walk-in or any thermal equipment.

Tip #5 – Don’t Assume the Temperature

You may have mapped an area dozens of times and could pretty much guess what the temperature is in that area. No matter how many times you have mapped an area, never “guess” the temp. Check it! A 2-degree difference can cause food to spoil, medicine to become unstable and perishable loads to become completely unusable. Company policy should state how often they must remap their warehouse (it is common to remap every 3 or 5 years). You have to remap if there is a major change (i.e., HVAC system or an extension of the area)For a trailer, if a major component is changed such as the reefer you need to re-qualify it (or through change control) and remap it.

Tip #6 – Map After an Expansion or Change of Location

Even if a new warehouse or storage unit is constructed to be identical to the old one, map it. A slight difference in the external temperature or climate can change the temperature on the inside. If you are expanding your warehouse or getting a longer bed for a transportation vehicle, you will need to map the inside again to consider the new layout and extra space. Even though you have strictly identical trailers each of them must be mapped. No matrixing is allowed. It is the same for a fridge, freezer…etc.

Tip #7 – When the Seasons Change, Re-map

The external temperatures, particularly in the winter or summer can have a huge impact on the cooling system in warehouses and vehicles. The temperature may have to be lowered slightly to keep the inside stable. To find out if this is necessary, you will have to map during summer and winter extremes. An intermediate season mapping in the fall or spring is recommended to insure the most complete study is done.

Tip #8 – Map Dead Areas

This is especially important when storing or transporting items such as medicines or food. Dead areas are areas with relatively low air circulation such as corners or lower shelves. Before doing a mapping, we work with the layout of the customer to cover each space. Even the dock is important. As soon as you have a pallet on the floor, even for a couple of hours, it is considered as storage and must be mapped and monitored. Think of your quarantine area, a dock where a pallet could be placed waiting to be loaded in a trailer, and high racking.

Tip #9 – Take Note of Issues in Temperature

If you are mapping out a warehouse, storage unit, vehicle, or room, make sure to take note of any wild fluctuations in temperature. If every time you map a certain area and it is 50 degrees, and the next time you map and it is 57 degrees, this may denote a problem in the cooling system for example.

Tip #10 – Map out Every Location in the Vehicle

Just because one area of a vehicle is cold does not mean the entire vehicle has the same temperature. When mapping the temperature in a transportation vehicle, make sure to note which part of the vehicle has that temperature. To be more thorough, map out several points in the vehicle, notating each point and its corresponding temp.

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