Introduction
An Ultra-Low Temperature (ULT) Freezer typically operates within the temperature range of -40 °C to -860C to safely preserve critical biological samples over long periods.
- Purpose: Protects highly sensitive biological materials from thermal degradation.
- Standard Settings: Most laboratories set their units to a standard of -80 °C.
- Configurations: Available in both upright (easy access) and chest (superior thermal efficiency) models.
Operating Principle
ULT freezers rely on a two-stage cascade refrigeration system to achieve extreme temperatures:
- Stage One (High-Stage): A standard compressor cycle cools a central heat exchanger down to approximately -40 °C.
- Stage Two (Low-Stage): A specialized low-temperature compressor cycle takes heat from the sample chamber and transfers it to the first cycle’s heat exchanger.
- Insulation: Uses high-density polyurethane foam or vacuum insulation panels to minimize heat gain from the external room environment.
Handling Procedure
- Personal Protective Equipment (PPE): Always wear heavy insulated cryogenic gloves and safety glasses to prevent frostbite.
- Door Management: Minimize door opening times to prevent ambient moisture from entering and forming ice.
- Sample Loading: Inventory samples systematically using internal racks and boxes to reduce search time.
- Maintenance: Regularly scrape away internal frost buildup and clean the condenser filter every two to three months.
- Vacuum Equalization: Wait a few minutes before reopening a recently closed door to let the vacuum relief valve normalize internal pressure.
Applications
- Molecular Biology: Long-term storage of DNA, RNA, oligonucleotides, and extracted proteins.
- Clinical Medicine: Preservation of viral and bacterial samples, blood plasma, and tissue biopsies.
- Vaccine Storage: Distribution holding for temperature-sensitive mRNA vaccines and biologics.
- Industrial Testing: Material stress testing and preservation of specialized chemical compounds.
Keynotes
- Ambient Conditions: Keep the freezer in a well-ventilated, air-conditioned room (<250 C) to prevent compressor burnout.
- Backup Power: Connect the unit directly to an emergency generator circuit to ensure operation during power grid failures.
- Backup CO2/LN2 Systems: Install liquid carbon dioxide or liquid nitrogen backup injection kits for automated emergency cooling.
- Clearance: Maintain 15-20 cm of clearance around the sides and back for proper heat dissipation.
Further Readings
- https://www.testronixinstruments.com/blog/ultra-low-deep-freezer-diagram-working-principle-and-uses/
- https://www.stirlingultracold.com/how-to-properly-use-an-ultra-low-temperature-freezer/
- https://www.drawellanalytical.com/what-are-ultra-low-temperature-freezers/
- https://caresourceglobal.com/ultra-low-temperature-freezer-professional-ultra-cold-storage-for-scientific-and-lab-needs/
- https://www.360medical.ca/blogs/news/ultra-low-freezer-safety-dos-and-donts-for-your-lab
- https://www.stirlingultracold.com/liquid-nitrogen-for-storage/
- https://www.igenels.com/category/microbiology-lab-instruments/
- https://www.froilabo.com/blog/ultra-low-temperature-freezer/
- https://www.nwrinc.com/industry-insights/common-challenges-in-ult-refrigeration-for-blood-plasma
- https://profilab24.com/en/laboratory/refrigerators-cooling-technology/binder-ultraguard-uf-v-700-ultra-low-temperature-freezer
- https://blog.cmecorp.com/cold-storage-guide-for-healthcare-and-life-sciences
- https://www.thermofisher.com/search/browse/featured/us/en/80013384