Advanced cold storage units are critical equipment for most laboratories to keep delicate and temperature-sensitive items at the right temperature environment.
Laboratories store many biological materials, like simple biomolecules like oligonucleotides and proteins, and complex items, such as cells and tissues. And these materials are sensitive to heat and require freezing temperature environments for storage. So, laboratories need to store such items in ultra-low temperature freezers (ULT), which operate within the -50 to -80 degrees C temperature range.
When you think of investing in a ULT, its temperature range cannot be the only consideration. You need to consider a slew of factors to land on the perfect unit for your laboratory.
Capacity
The capacity of the ULT freezer determines the total amount of items you can store in it. So, decide which volume of things you are going to keep in the freezer. Usually, the price varies as the capacity. The higher the capacity, the higher is the price. If you require small storage space, go for a smaller ULT freezer that will lower long-term operating costs and have a smaller physical footprint.
Reliability
Reliability is an essential factor during your selection of an ultracold freezer because you need to ensure that the unit you choose will store your precious items effectively.
The unit you select should give you the confidence that there will be proper control of the internal temperature. The freezer should maintain the set temperature for 24 hours.
In a ULT freezer, different internal locations within the cabinet are warmer or colder than the average. As such, select a unit that minimizes this temperature spread, also known as peak variation.
Usually, ULT freezers with minimal peak variation deliver a more uniform temperature within the cabinet and temperature stability.
Physical Footprint
It is a good practice to use a freezer that takes up minimal space in your laboratory so that you can use more space for your laboratory work. It will help if you go for an upright ULT freezer as it has less physical footprint than the chest design. And what is more is that the upright versions have larger capacities, enabling you to store more. However, if any of your researchers have physical limitations and mobility issues, then the chest design is preferable.
Energy Efficiency
Check out the power consumption of your prospective ULT freezer. Typically, these freezers come with designs such as double doors, gasket seals, and polyurethane heat insulation to maximize energy efficiency. But there can be differences in energy consumption due to the type of refrigerant and compressor of different units. Therefore, choose a unit with the least energy consumption to minimize your electricity bills.
Temperature Consistency
The main aim of investing in a ULT freezer is to maintain a uniform temperature within the unit. Biological samples, such as patient tissues, need a uniform temperature to remain potent. If the temperature fluctuates beyond the prescribed range, the precious samples will get damaged. So, the ULT freezer you choose must maintain a uniform temperature.
Examine the recovery time to -80 degrees C after you open and close the door, during which warm air enters into the unit. The lower the recovery time, the better is the unit. The entry of warm air affects the temperature uniformity.
It will help if you choose a ULT freezer with multiple inner doors for different storage shelves instead of a single inner door.
In this way, the door opening will affect only the particular shelf’s temperature. And it consumes less energy during its reverting to the original interior temperature.
Backup Cooling
Ensure a backup cooling system in your prospective ULT freezer as the internal temperature will get compromised during power failures.
ULT freezers are usually based on cascade refrigeration technology, which requires electricity. During power failures, the cooling stops, so the stored biological samples will get compromised.
Therefore, check whether there is a backup cooling system in your prospective ULT freezer. If it is not there, then find out you can install one at an additional cost.
The typical backup cooling systems are liquefied nitrogen and carbon dioxide. While liquid nitrogen can maintain temperature up to -80 degrees C, carbon dioxide can keep the temperature down to -70 degrees C.
Noise
Bear in mind that ULT freezers are noisy. Due to the intensive working of fans, ULT freezers make noise while working, which can distract researchers and make them uncomfortable. Noise levels vary with the type of ULT freezer. Usually, the larger the freezer, the more is the noise level.
Manufacturers usually provide the noise levels in their manuals. You can use them as a point of reference.
User Interface
Evaluate the user interface of the prospective ULT freezer. Most of the latest ULT freezer variants bear the WiFi connecting facility that allows you to connect the freezer remotely.
The feature is useful when monitoring the freezer temperature during non-working hours or in situations when the lab activities get disrupted.
The modern user interface includes buttons and touchscreens that allow access to freezer information like voltages and door openings. You can also adjust settings like the set temperature, allowable temperature range, and alarm using them.
Conclusion
Purchasing a ULT freezer entails substantial investment. You need to make sure that your investment derives value. Choose a unit that will fulfill the needs of your laboratory. Look for features like easily maintainability, reliability, and energy efficiency in your prospective unit. Also, do not fall behind in selecting a reputed and reliable brand.
