Biological materials and reagents can be highly sensitive to temperature changes and require efficient and reliable storage solutions to maintain viability and maximize product shelf life. In particular, vaccine storage requires strict temperature control and uniformity. Changes in temperature have a significant impact on vaccine integrity, leading to loss of time and resources. Therefore, it is important to measure the temperature performance of refrigerators and freezers to protect samples using methods such as peak variation.

technology network recently talked Drew Buskirk, Senior Product Manager, Thermo Fisher Scientific. Buskirk also discusses NSF 456. This is the new vaccine standard published by NSF International – and how its implementation will help reduce vaccine waste.

Anna MacDonald (AM): Can you explain what the peak variation is?

Drew Buskirk (DB): Peak variation is the difference between the minimum and maximum temperature measured during performance testing of a refrigerator or freezer. Just deltas, no averages or additional calculations. The number of probes used, the type of probes used, and whether they are weighted or open air, but the metric represents the worst case temperature of the entire cabinet.

AM: Why is recognizing peak variation important?

Database: Peak variation is important for two reasons. First, it shows the user how well the unit circulates air throughout the cabinet. This is a good indicator of overall unit performance. Second, it gives the user a clear picture of potential cold or warm spots in the cabinet that could be problematic for temperature sensitive cargo. The more probe locations in the test, the better the user’s coverage and visibility to potential problem areas.

AM: How has peak variation in life science refrigerators been traditionally measured? What are the limitations of this approach?

Database: Traditionally, peak variation was measured in a cabinet with 9 probe positions, 4 in the corners of the top shelf, 4 in the corners of the bottom shelf, and 1 in the middle of the cabinet. While it seems intuitive that this is the area where temperature extremes are most likely to occur, it is not always the case. The airflow through the cabinet can be changed according to the position of the fans and baffles, not just the corners inside the cabinet. This can create cold spots in unexpected areas along the side walls or back wall that traditional peak variation tests cannot cover. The more places and the wider the cabinet coverage, the better the airflow will be represented.

AM: How does Thermo Fisher Scientific measure the temperature performance of their products?

Database: Thermo Fisher Scientific measures 24 locations in the cabinet and calculates peak variability, stability, and uniformity. Stability is the maximum temperature difference over the entire test at a specific location. The average stability during cycling is the published value. Uniformity is the maximum temperature difference across all thermocouples at a given instant. Thermo Fisher Scientific publishes the average uniformity for the cycle portion of the test.

In addition to whole-cabinet temperature measurements, another important metric is the 1-minute Door Open Recovery (DOR). This is the time it takes for the unit to return to set point after the door is open for his one minute, and is a good measure of the unit’s heat load capacity and air circulation capacity. Refrigerators are rarely closed all day, they are opened frequently. Laboratory-grade refrigerators must be able to handle the rigors of customer use while maintaining temperatures suitable for sensitive cargo.

AM: Can you tell us more about the NSF 456 standard and its significance?

Database: Vaccine waste is a major global problem, with the World Health Organization estimating that approximately 50% of all vaccines are wasted each year. This is a huge cost, not just in terms of money, but in terms of being able to deliver critical healthcare solutions around the world.

Historically, vaccine storage guidance has been vague, resulting in customers using a variety of solutions for vaccine storage. The new NSF 456 vaccine standard provides clear guidance to both users and manufacturers regarding design, thermal performance and documentation requirements necessary to optimally and safely store vaccines. This new standard is a great example of industry working together to solve critical infrastructure problems and Thermo Fisher Scientific is extremely proud to be a partner in helping develop this standard. I’m here.

AM: how TSX series Do high-performance refrigerator-freezer combinations ensure sample integrity?

Database: All Thermo Fisher Scientific TSX lab refrigerators and freezers include a variable speed compressor that allows you to adjust the speed according to your cooling needs and an automatic adjustment control that optimizes the operating speed of the compressor for current conditions. Drive technology is used. If the refrigerator or freezer is frequently opened or samples are added, the cooling capacity can be increased so that the unit returns to set point as quickly as possible. This allows TSX refrigerators and freezers to maintain tight peak fluctuation numbers and achieve faster door open recovery.

Drew Buskirk was talking to Anna MacDonald, a science writer at Technology Networks.