Introduction
When using Element-T devices to monitor and alert on temperature excursions inside cold storage units, it's important to understand how and why the readings from our probes may differ from those of the internal temperature sensors. Note that below, we may refer to units as 'Freezers' but the same may apply to Refrigerators.
Why Temperature Readings Can Differ
Measurement Focus:
- The Element-T: Our Element-T devices are designed to measure air temperature within cold storage units. These probes provide real-time data every 15 seconds, which is crucial for monitoring freezer health, predicting door openings, and ensuring optimal storage conditions.
- Internal Freezer Probes: The temperature sensors inside the freezer are designed to monitor and maintain a temperature close to the setpoint. They are calibrated to ensure accuracy at specific locations, but they may not track temperature variations throughout the entire chamber. Consequently, warmer or colder spots can exist within the freezer, which is why it's important to consider air temperature measurements from our IoT probes for a more comprehensive view of the environment.
Placement:
- Air Temperature Variability: Air temperature within a freezer can vary significantly depending on the location of the probe. Factors such as the placement of shelves, the frequency of door openings, and the distribution of cold air can all impact temperature readings. This variability is why our probes might show different readings compared to the internal sensors.
- Temperature Mapping Services: Many Pharma customers invest in temperature mapping services to precisely understand temperature distribution within their freezers. This process involves placing multiple temperature probes throughout the freezer to identify temperature gradients and ensure compliance with regulatory requirements. The insights gained from temperature mapping help in optimizing probe placement and improving overall monitoring accuracy. If interested Elemental Machines can assist with temp mapping for your temperature controlled units.
Impact of Chamber Fill Level:
- Air Circulation: The amount of material inside the freezer affects how air circulates. If the freezer is excessively full, airflow might be obstructed, leading to localized temperature gradients and potential variations. Conversely, in an empty or partially full freezer, there is less thermal mass to stabilize temperature, resulting in more noticeable swings. The lack of stored materials can lead to greater temperature variance as the air warms and cools more rapidly with changes in the cooling cycle and door openings.
- Thermal Mass: As mentioned above, the contents of the chamber contribute to its thermal mass. A full freezer for example has more thermal mass, which can help stabilize the temperature but may also lead to slower recovery after door openings or power fluctuations.
- Temperature Regulation: With varying levels of contents, the internal temperature sensors may face challenges in maintaining a consistent temperature. For example, if a freezer is only partially full, the cooling system might struggle to maintain uniform temperature distribution as effectively as it would in a fully stocked freezer.
Why It Matters
Understanding these differences is crucial for interpreting temperature data accurately and ensuring proper storage conditions for your sensitive materials. While the internal probes are optimized for controlling the freezer's temperature, the Element-T probes can provide a broader view of the air temperature environment, which is essential for comprehensive monitoring and critical alerting. In the next section, we will discuss requirements on what your team may need from the Element-T devices and how to weigh those options and choose the right configuration.
Requirements and Goals
- Matching what you see on the unit vs. Fastest possible alerts: When customers question why our values might not match the internal freezer sensors, we often ask about their primary goals with monitoring. If the goal is to match the temperature closely with the internal sensors, it is advisable to place our sensor near the internal probe, typically at the back and bottom of the chamber. However, if the goal is to obtain quick alerts for possible failures or doors being left open, we recommend placing the sensor higher in the chamber. This placement better reacts to those changes in air temperature, providing the data that allows our alert engine to act on quickly.
- Implementing Thermal Buffers: Some customers find that they do not need the sensitivity of our probes and prefer to monitor closely what the temperature is on the materials or samples. A way to do this is to use a thermal buffer such as glass beads or glycol. This will effectively 'smooth over' the graph and up and down appearance of the compressor cycle as well as simulate how a material will act inside the chamber. One downside of this method is that the probe will no longer be measuring air temperature and therefore may be slower to catch excursions and the analytics mentioned in the next section would not be available.
Analytics / Additional Insights:
- Data Science: Our Data Science team has created algorithms that use the air temperature data to provide additional insights, such as door open events over time, smart context alerts or changes in freezer health (when used in conjunction with Element-U devices). These capabilities are based on the continuous monitoring of air temperature and can help proactively manage the freezer environment(s). For questions on utilizing these additional analytics and insights, reach out to your Customer Success Manager.
Conclusion
Temperature variations in freezers are common and can be influenced by the factors mentioned above. By recognizing that variations are normal and using the information in this article, you can make informed decisions about how to configure your temperature monitoring system to best meet your specific requirements, whether that’s for precise temperature matching of samples or for effective alerting and analytics.
If you have any concerns about temperature discrepancies or have additional questions on best practices, please submit a ticket or reach out to Customer Success and Activation. We are here to help ensure that your monitoring system is configured to meet your specific needs and maintain the integrity of your stored materials.
Helpful Links:
Here is a link to a page that contains the user manuals for our Element-T devices.
https://elementalmachines.freshdesk.com/a/solutions/articles/19000113216