Laboratories worldwide rely on ultra-low temperature (ULT) freezers to store biological samples and materials at a temperature range of -50ºC to -86ºC. For many labs, an ultra-low freezer houses tens of thousands of dollars worth of product and irreplaceable biological samples.
Laboratory professionals want the peace of mind that a reliable ultra-low freezer provides but must also consider storage capacity and energy usage when purchasing a freezer.
With so many options available, it’s imperative to conduct thorough research when selecting a ULT freezer.
The Right Questions to Ask About ULT Freezers
Ultra-low temperature freezers have a lifespan of about 10-12 years if maintained properly and will be responsible for the temperature stability and long-term storage of your precious samples. Therefore, it is important to consider the following questions when looking to purchase a ULT freezer.
What Is Your Budget?
The cost of a ULT freezer goes beyond just purchasing the unit. You should also include the sum of the purchase price, cost of energy, facility cooling, floor space, and maintenance/replacement parts when you create your budget.
The price of the freezer will vary depending on your needs. Low-cost freezers will not come with as many innovative, risk-mitigating features when compared to higher-end freezers.
Where Will the Ultra-Low Freezer Stay?
When deciding where to place your freezer, you should consider the physical footprint of the ULT freezer as well as the capacity requirements you will need. Labs with limited space often face size constraints as most ULT freezers require clearance for door swings and 5-6 inches away from the wall for ventilation
Upright freezers, such as the SU780XLE, have the smallest physical footprint and largest cu ft/m storage capacity compared to conventional upright and chest freezer designs. The SU780XLE is unique in that it does not require wall clearance because it expels less heat while venting it more effectively in to the room than the standard compressor-based models, significantly reducing the ventilation and HVAC requirements. Many universities and research labs prefer upright ULT freezers because they provide the largest capacity at the lowest price and minimize energy consumption.
Other options, such as the SU105UE, are ideal for laboratories that don’t have room for a large upright freezer or need personal bench side storage.
How Can the Exterior Environment Impact Your Freezer?
ULT freezers should be placed in rooms no hotter than 32℃. Conventional ULT freezers also require several inches of ventilation on the top, back, and sides and should be placed far away from heating units or exterior doors.
If there is more than one ULT in a room, it is essential to avoid close side-by-side placement unless located in a specially designed freezer farm with adequate room HVAC capacity and air circulation.
How Can You Combine Energy Efficiency and Reliability?
Reliable sample storage is the overall goal when it comes to purchasing a ULT freezer. Reliability is also associated with sample integrity. Your samples are only reliable if the freezer is able to maintain the temperature at a constant rate and have adequate temperature recovery every time the freezer door is opened.
In order to provide a reliable product, ULT freezers are typically designed with features such as double doors, gasket seals, or heat insulation to maximize energy efficiency. Many traditional ULT freezers are equipped with cascade or auto-cascade cooling technology which generates heat and noise and needs a significant amount of energy and maintenance. New energy-efficient units are available on the market to provide energy savings. The Stirling Ultracold SU780XLE does not use a typical compressor. Instead, it relies on advanced free-piston Stirling engine technology that doesn’t compromise ULT performance in order to achieve high efficiency. This engine works continuously, opposed to the stop-start operation of a traditional ULT freezer compressor. Manufacturers are also more aware of the carbon footprints from research labs and label products as ENERGY STAR certified to identify the ones that are environmentally friendly.
What Is Your Plan B?
If you are located in an area that experiences frequent power failures, then a backup kit is something to consider. CO2 backup kits alert laboratory staff of a power failure while maintaining a set temperature for a short amount of time.
Backup generators are commonly used for research facilities, especially in areas that are susceptible to brownouts, and blackouts from hurricanes and other natural events.
Factor in Durability
As previously stated, ULT freezers typically have a lifespan of 10-12 years if they are kept in a temperature-regulated room and maintenance regularly. The freezer’s lifespan decreases when they are placed in areas such as hallways, near open doorways, or by windows with limited ventilation or exposure to high ambient temperatures.
Moreover, proper maintenance such as cleaning dust from the filters, removing frost build-up, and cleaning the door gaskets is necessary to ensure the ULT freezer remains in satisfactory operating condition and will avoid shortening the usable lifespan. Just a few simple activities on a regular basis can minimize energy consumption and ensure that the manufacturer’s warranty and recommendations are met.
How does an ultra-low temperature freezer work?
Most ULT freezers use cascade refrigeration which consists of one or two compressors, seamless door seals, and a heat exchanger to reduce interior cabinet temperature to as low as -86ºC. Stirling Ultracold is unique in that its compressor-free design provides an energy-efficient ULT freezer that maintains storage temperature setpoints between -20ºC to -86ºC.
What are ultra-low temperature freezers used for?
Laboratories and biorepositories use ULT freezers to store biologics, tissues, drugs, enzymes, and other samples needed for patient care or medical research.
Who makes ultra-low temperature freezers?
Customers can find a variety of ULT freezer manufacturers, including our renowned engineering and manufacturing team at Stirling Ultracold.
What refrigerant do ultra-low freezers use?
ULT freezers switched to HCFC refrigerants after CFCs were banned, although many still use F-Gases or hydrofluorocarbons (HFCs), which are potent greenhouse gases that cause ozone depletion along with global warming effects. More recently, ULT’s are using natural hydrocarbon refrigerants, such as R-170 (Ethane), which has a Global Warming Potential (GWP) that is less than 0.04% of F-Gases.
How to Purchase an Ultra-Low Temp Freezer from Stirling UltraCold
A variety of ULT freezers exist on the market. Doing your own research prior to purchasing a ULT freezer will help you avoid a costly mistake and lead you to the most reliable and secure product for your samples. Stirling Ultracold has a worldwide network of certified Distributors, Contract Service Technicians, and Direct Sales Professionals ready to serve you.