Eppendorf North America
Product Manager
There are few pieces of lab equipment that hold more precious materials than ultra-low temperature (ULT) freezers. These freezers are trusted repositories where researchers store their assets. ULT freezers hold everything from super-rare patient samples and materials from years of continuing research to daily-use, routine solutions. When looking to buy new or replace an older model, you might think that purchasing an energy-efficient laboratory freezer is a simple and straightforward decision.
But when your samples, research and, more importantly, your time are at the mercy of this trusted piece of equipment, it is worth doing the research up-front to find the right one to fit your needs. Technological improvements in cold storage have resulted in more energy-efficient operation of ULT freezers. Advances in compressor function, insulation and cabinet design have resulted in greater efficiencies in sample storage. What to do with your old unit is another matter to think about. Consider these tips as you begin the search for your next ULT freezer.
Understand your needs
As with purchasing an appliance for your home, you should research how your needs will be met. What types of materials do you plan on storing? Do you need to access your samples every day, or are they being stored for long periods? There are several ULT freezer designs, with varying sizes, storage capacities, footprints and ease of access. Common freezer styles include upright, chest, table-top and under-bench. For frequent use, an upright ULT freezer allows easy access, while a chest ULT freezer provides safe long-term storage for items that are accessed less frequently. Table-top and under-bench ULT freezers are also available if space is limited, or freezer access is required at your workbench.
Energy efficiency
ULT freezers consume a great deal of energy, because they work relentlessly to maintain extremely low temperatures; therefore, power use should factor into your decision process. According to a U.S. Department of Energy report, a conventional, full-size -80oC freezer uses approximately the same amount of energy as the average U.S. household—up to 22 kWh/day [1]. The good news is that some companies have made innovations to the design and function of ULT freezers and offer dependable yet energy-efficient machines that don’t compromise on performance or dependability.
Advances in compressor design, insulation and cabinet organization have all resulted in greater efficiencies and energy cost savings. Some units are now designed to reduce energy consumption by more than 59% and are 98% recyclable by weight. Also inquire about the outer door gasket as part of the freezer’s design. The outer door is the most vulnerable part of the freezer, when it comes to maintaining cold air within the chamber. Look for frost-resistant gaskets that can also be cleaned easily and safely to optimize the efficiency of your ULT freezer. Additional improvements include replacing polyurethane foam with vacuum-insulated panels, thereby creating better isolated environmental conditions within the cabinet. This alteration also makes the walls of the ULT freezer thinner, which translates to more usable storage space for researchers within the laboratory.
“Back it up”
Power outages occur unexpectedly, so it is important to understand how your samples will be protected if there is a system failure. Instant backup protection and a good monitoring and alarm system could mean the difference between losing precious samples and completing the next experiment after a power outage. Some manufacturers offer a battery backup system or ports for CO2 or LN2 in case of power interruption. There are freezers that can be fitted with an optional chart recorder to provide independent temperature recording. Some systems offer an automatic reset that restarts the freezer at random 15-second intervals to protect the microprocessor controller from damage by electrical spikes. Review the latest failure-prevention options available for ULT freezers to find the best system to protect your samples.
Don’t let the cold air out
If you plan on accessing your samples frequently over short periods of time, it is important to have a freezer that opens and re-opens easily. Options like an easy-to-open door that enables one-handed operation might be worth considering. Other features include a heated port that releases the vacuum seal, enabling the outer door to be re-opened quickly, and an inner door system with ice-proof latches. These capabilities can benefit researchers who require periodic access to their frozen materials.
Easy maintenance and monitoring
Regular maintenance improves the operation of ULT freezers by reducing the energy consumption and helping the unit achieve its set-point temperature on a consistent basis. According to figures calculated by Eppendorf, an unmaintained freezer can use 12% to 25% more energy than a maintained freezer and may require an additional $280 per year to operate. Look for easy-maintenance design features, such as frost-resistant gaskets, easy diagnostics and a front-mounted filter that provides easy access when cleaning or changing. Also, a freezer with inner doors that easily lift off without tools will be welcomed during defrosting and cleaning sessions.
Manufacturer’s warranty
No one wants to buy a new freezer and have it break a year later, but that can happen. Be sure to check the manufacturer’s warranty on parts and labor, and discuss with the sales representative the service options that are covered and available with the warranty.
There are many options to consider when selecting a ULT freezer. The following points will assist in the decision-making process:
• Look for energy savings, but don’t compromise on performance and dependability. Your samples are precious, and the environment they are stored in is just as important.
• Review manufacturers’ product information to better understand the different features and options.
• Speak with your sales representatives to learn which ULT freezer will best serve your storage needs.
• Inquire about the sustainability practices of each manufacturer. Do the company and corporate culture align with sustainability goals? Do they have a product-removal and -recycling program?
There are energy-efficient and environmentally responsible ULT freezer options that don’t compromise on performance and will provide many years of reliable and dependable storage for your precious samples.
Reference
[1] U.S. Department of Energy, “Field Demonstration of High-Efficiency Ultra-Low-Temperature Laboratory Freezers,” September 2014.
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