What are Ultra Freezers and how do they work?

For battery and storage testing, discover the FDM battery test chamber, designed for testing under controlled conditions.

Ultra Freezer FDM 650 liters Capacity 30 Boxes
(23x23x20cm)

What is an Ultra Freezer?

Theultrasonic freezer is one of the main instruments used in research laboratories. The ULT freezer is designed to safeguard biological samples essential for laboratory research by keeping them at extremely low temperatures.

The operating temperature can vary from -45°C to -89°C. There are many features that make an Ultra Freezer an extremely reliable machine for scientific research.

We summarize them below, thanks to our years of experience in the field and ongoing collaboration with some of the most important scientific researchers in the world.

Types

It is generally available in two versions: vertical cabinet and horizontal well with top access. The vertical version is the most popular, as laboratories are increasingly seeking to save space and facilitate mobility.

Volumes

Low-temperature freezers can vary in internal storage volume. They range from 200 liters to a maximum of 800 liters. Some manufacturers, such as FDM, also offer customized versions upon request.

Structure

TheUltra Freezer is equipped with internal shelvesfor storing research samples. Each shelf is closed by an internal door to maintain a uniform temperature on shelves where no samples are being taken or placed.

Insulation

Insulation is a key component of the Ultra Freezer. To maintain the cold stored inside the cabinet, high-thermal, non-toxic polyurethane insulation is used between the outer and inner walls, allowing the desired temperature to be reached and maintained.

Gasket

Another key element for ensuring the correct temperature is reached is the gasket, which runs along the entire perimeter of the main access door. The most effective ones are those with a quadruple silicone seal.

Access door

The access door , also insulated with polyurethane, guarantees maximum cold retention and is locked by an external lock generally equipped with a security key.

Swivel wheels

The most practical laboratory freezers are equipped with swivel wheels at their base, making it easier to move them around the laboratory.

Controllers

Freezers are equipped with PLC electronic controllers and a display showing the freezing parameters. The entire control system is generally backed up by a battery, which allows the digital temperature display and alarms to function even in the event of a power outage. 

How does the refrigeration circuit of an Ultra Freezer work?

Refrigeration systems can have a single compressor or a cascade of two compressors (two-stage systems). In the latter case, there are two refrigeration circuits, connected so that the evaporator of one cools the condenser of the other, facilitating the condensation of the compressed gas in the first circuit.

Air-cooled condensers are generally used in laboratory refrigeration systems. These condensers consist of coils of tubes (copper or copper-aluminum) arranged to provide the maximum heat exchange surface area. In ultra-low temperature freezers , the cooling air is circulated by a motor-driven fan, and the refrigerant is expanded using capillary tubes.

Evaporation occurs through steel plate heat exchangers, located inside the chamber, or through a coil. Thecoil evaporator in chest freezers is arranged along the walls and bottom, while in upright freezers it runs along the walls and top. The coil in the chamber eliminates the heat exchange efficiency problems inherent in freezers with the coil in the insulation cavity.

Refrigerants used in ULT freezers

Refrigerants are chosen from gaseous chemical compounds that can be easily liquefied and are characterized by certain properties, such as high critical temperature and low critical pressure, low hazard and toxicity. 

They are indicated by the letter R followed by a number that refers to the atoms in the molecule.

Each refrigeration system must be hermetically sealed and contain environmentally friendly HFC free from CFCs and HCFCs, which are non-toxic, non-explosive and non-flammable. 

The most efficient and environmentally friendly refrigerants used in ultra-low temperature freezers are typically R170 and R449A.

With the new European Regulation EU 517/2014, manufacturers of ultra-freezers must follow the guidelines to allow their use even after 2030. Therefore they must use environmentally friendly refrigerants:

R717 (ammonia)

R744 (carbon dioxide)

R170 (ethane)

R290 (CARE 40) Propane

R600a (CARE 10) Isobutane

R1150 (ethylene) R1270 (CARE 45) Propylene

R449A (zeotropic HFO)

Find out how FDM is constantly searching for the best refrigerant gases

What accessories can an Ultra Freezer have?

Typically, the following accessories are provided: 

an emergency CO2 and/or LN2 system (both with independent power supply, probe and battery). 

Furthermore, to track the temperature of the chamber, freezers can be equipped with a weekly temperature recorder with graph discs, which today have almost completely been replaced by digital ones. 

According to current international standards, the recorder is mandatory for freezers at -45°C and -86°C intended for the storage of blood products. 

Other accessories include: containers, drawers, and various types of steel racks for storing cryoboxes, microplates, blood bags, and test tubes designed for storage at low and very low temperatures. 

When working inside ultra-low temperature freezers, it is necessary to use appropriate protective clothing for head protection, using leather gloves for hand protection, and overalls and gowns for body protection.

Request a Price for a -80°C Ultra Freezer

Learn more: Discover our FDM CO2 laboratory test chamber, designed and manufactured by FDM Environment Makers.

Reference Standards

• ISO 15189 — Medical laboratories — Requirements for quality and competence
• CLSI GP44-A4 — Procedures for the Handling and Processing of Blood Specimens
• WHO TRS 961 Annex 9 — Storage and transport of time- and temperature-sensitive products
• EU GDP 2013/C 343/01 — Good Distribution Practice
• EN 60086-1 — Primary batteries — General part (reference to battery storage)
• NFPA 55 — Compressed Gases and Cryogenic Fluids Code (for ultracong. at LN₂)

Authoritative Sources

• WHO — Vaccines & Biologicals.
• CLSI — Clinical and Laboratory Standards Institute.
• NIST Biorepository Standards.

Frequently Asked Questions about Ultra-Low Freezers

What is a -80°C ultra-freezer used for?

Temperatures below -70°C block enzymatic activity and inhibit microbial growth indefinitely. Applications: biobanking (DNA/RNA samples, cell lines, plasma), mRNA vaccines (Pfizer-BioNTech requires -80/-60°C for long-term transport), enzymes and proteins , and surgical tissue . Below -130°C (LN₂ cryogenic freezers), intracellular water recrystallization is also blocked, allowing for decades of live cell preservation.

What's the difference between a mechanical and cryogenic ultrafreezer?

Mechanical -80°C: 2-stage cascade compressor (R-449A + R-508B/R-170), no cryogenic gas, simpler but limit -86°C. Cryogenic LN₂ -150/-196°C: liquid nitrogen tank with vapor-phase controller (samples above LN₂) or liquid-phase (immersed). Much lower operating range but requires LN₂ logistics (weekly refill, risk of asphyxiation in closed chambers, NFPA 55 certification). For mRNA vaccines, mechanical -80 is sufficient; for stem cells, cryogenic is required.

What alarm and monitoring systems are mandatory?

For GLP/GxP and biobanking applications : (1) 21 CFR Part 11 compliant datalogger with audit trail; (2) ACCREDIA calibrated PT100 Class A probe ; (3) Multi-threshold alarms (warning -70°C / critical -65°C) with SMS/email notification; (4) CO₂ or LN₂ backup to delay temperature rise in case of blackout; (5) UPS for 15-30 min compressor autonomy; (6) 24/7 monitoring with intervention within 15 min.

Typical power consumption of an ULT -80°C?

A standard 500-800L ULT consumes 15-25 kWh/day (≈5,500-9,000 kWh/year). Energy Star-certified models reduce consumption to 8-12 kWh/day (-50% consumption) thanks to variable-speed compressors (VSD), natural refrigerants R-290/R-170, and VIP (Vacuum Insulation Panels). A biobank with 50 ULTs consumes as much as 100 households—this is why universities like Harvard and Stanford are promoting "freezer challenge" campaigns to go from -80 to -70°C with 30-40% energy savings without scientific compromises.