What to Consider When Selecting an Ultra-Low Temperature Freezer

Biotechnology & Healthcare Tips for Successful Lab Management
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Ultra-low temperature (ULT) freezers are essential to any lab environment, as they play a critical role in helping to ensure the safe storage of precious samples. Operating within the -50°C to -80°C range, ULTs are used to store a variety of analytes and products, from biospecimen samples to enzymes and drugs.

For many labs, a ULT stores hundreds of thousands of dollars in product and plays a vital part in protecting samples critical to the future of their research. Lab professionals demand reliability, but must also think about storage capacity, energy usage, noise considerations and other factors that could have substantial impacts on their daily workflows and operational costs.

Given all these factors, ULT freezers’ capabilities cannot be measured by one attribute alone. Rather, their performance is a cumulative measure of these collective considerations – all of which ultimately translate into one key takeaway: peace of mind. With so many different products today, it’s imperative that you do your research when selecting a ULT freezer.

When evaluating your options to identify a truly superior model, be sure to consider:


Reliable sample storage is the first priority when it comes to a cold storage decision because your science depends on having high-quality, properly stored samples. A superior freezer should give you confidence that cabinet temperature is being strictly controlled. Moreover, you shouldn’t have to worry about your samples when you turn off the lights at night – your ULT needs to get cold and stay cold.

While every freezer has locations within the cabinet that are warmer or colder than the average, look for units that minimize this temperature spread, also known as peak variation. Freezers with good (i.e. minimal) peak variation deliver crucial temperature uniformity within the cabinet and, equally important, temperature stability. Both factors are critical to ensuring samples don’t repeatedly thaw and freeze as the freezer door is opened throughout the day. Good peak variation also allows scientists to fully maximize storage capacity because they aren’t limiting themselves to “The Goldilocks Zone.”

When we think about reliability, we immediately think about sample integrity. Your samples are only reliable if the system that maintains that temperature is reliable as well. The critical piece of equipment in any ULT freezer is the compressor, but not all compressors are equal. Unlike systems that are constantly moving, the Thermo ScientificTM TSX series of ULTs utilizes a variable speed compressor powered by adaptive V-drive technology. Rather than running continuously, the V-drive system operates like a car, accelerating and decelerating in response to usage and the environment, delivering the needed cooling capacity for the given situation. This gradual ramp up and slow down helps reduce the stress on the system and extend the life of the compressor – so much so that we offer a lifetime warranty not because we have to, but because we can!


Ease-of-use is another important consideration when selecting a ULT. Be mindful of the features inherent in the units you’re evaluating and look for robust interfaces that offer monitoring and control support. For example, remote monitoring capabilities can reduce the risk of undetected malfunctions during off-hours, storms or other natural events that could put your samples at risk. Many ULTs on the market today incorporate icons to advise users of alarm status for power failure as well as warm or cold excursions or if the door was left ajar. Furthermore, seek a unit that uses numerical indicators of operating temperature to minimize user error when checking and reporting temperature status.

Additionally, consider the ergonomic advantages of the system you’re evaluating and how comfortable it will be to utilize that system every day. For example, an easy-open door that can be used one-handed can be overlooked at the time of purchase but becomes a very beneficial feature when you’re constantly carrying items, such as samples or notebooks, back and forth with you. Similarly, the height and depth of shelves is important to assess. Systems that don’t conform to the average individual’s height could put unintended physical stress on users who are constantly bending or reaching into it to load or retrieve samples.


Sample security should always be top of mind, but sustainability continues to become another important consideration when selecting lab technology. This is especially true with ULTs, as their low operating temperatures put them among the more energy-intensive lab solutions.

Fortunately, Thermo Scientific offers a number of energy-savings models that meet today’s sustainability demands without sacrificing on sample temperature protection. Our ULT freezers are specifically designed and engineered for the safe use of green hydrocarbon (HC) refrigerants that are in compliance with the U.S. Environmental Protection Agency’s (EPA) Significant New Alternatives Policy (SNAP) program, the European Union’s F-gas regulations, and other regulatory programs. These hydrocarbon refrigerants not only help improve system performance, but they do so with minimal environmental impact.

In some instances, commitment to reducing energy usage can lead to critical sacrifices in temperature control that may put samples at risk. Look for units and product providers that value energy efficiency but take a measured approach that maximizes sustainability without risking sample quality.


Finally, consider important features that enhance convenience, such as noise reduction. For years, the constant hum of ULT freezers relegated them to locations outside of the core lab workspace. Today, advancements to underlying compressor technology have made it possible to reduce noise considerably. In fact, the TSX series is up to 20 times quieter than competing technologies. This has allowed many labs to bring their ULTs back into the direct working environment, streamlining processes through quicker and easier sample access.

Additionally, units like those within the TSX series output less heat. This creates another compelling reason to bring them back into the main lab area, as they won’t make the surrounding space hotter. Furthermore, less heat output means less burden on the HVAC system, translating to lower energy bills. Another feature to consider is how the unit is powered. Plugging into a standard outlet means there are more options for where it can be located versus units with more specialized power requirements.

Finally, don’t forget to check with your sales reps on the product’s warranty before signing on the dotted line and to think about the long-term benefits of your provider partnerships. For example, the TSX compressor warranty extends beyond the life of the average compressor. We offer a 12-year warranty on a component that’s generally expected to last only 10 years because of the reliability of our V-drive technology. On top of this, our customers get the benefit of partnering with a leader in the field that can support future additions to their lab portfolios, including cold storage accessories and other workflow essentials.

We know a ULT is a large and costly investment, but it’s also an indispensable one. Make sure you’re considering all the factors that contribute to a superior ULT freezer before you purchase.

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