Cryogenic freezers are vacuum-insulated vessels that store biological samples in liquid nitrogen or in its vapour phase, at temperatures down to –196 °C, without a compressor. They differ in four design choices: neck width, construction material, storage phase and capacity. Together these decide how many samples fit, how easily you reach them and how much LN₂ evaporates each day.
The term causes some confusion. In labs, "cryogenic freezer" or "LN₂ freezer" usually means a liquid nitrogen storage tank, not a mechanical freezer and not a controlled rate freezer such as the BIOFREEZE®, which cools samples at a programmed rate before they go into storage. This article covers the storage vessels. It is not a buying guide; for procurement criteria, see our complete guide to buying liquid nitrogen storage tanks.
Every LN₂ freezer works on the same principle. An inner vessel holds the liquid nitrogen and the samples. An outer vessel surrounds it, and the space between them is held at high vacuum, usually with multi-layer insulation and an adsorbent that captures residual gas. The vacuum almost entirely stops heat transfer by conduction and convection.
The only solid connection between inside and outside is the neck. Most of the heat enters through it, and the evaporated nitrogen leaves through it. That is why the neck is where cryogenic freezer designs differ most.
Four design features define a cryogenic freezer. They can be combined fairly freely, but each one affects the others.
Narrow-neck vessels have a small opening. The evaporation surface is small, heat ingress is low and hold time is long. The trade-off is access: samples come out only in narrow canisters or tubes.
Wide-neck vessels open up the whole storage space. You can lift racks of cryo boxes directly and pass large bag formats through. In return, heat ingress rises, both at rest and every time the lid opens.
The eccentric tank opening sits between the two. The neck is placed off-centre, so the opening stays small, and a rotatable bottom brings each rack under it. On Consarctic® cryogenic tanks this design cuts LN₂ consumption by up to 30 % and keeps the vapour phase colder.
Aluminium is light and corrosion-resistant, a good fit for smaller vessels that get moved. The Consarctic® ABV+ Series covers 4 to 150 litres in aluminium, for cryovials, bags and straws.
Stainless steel is tougher, easier to clean and built for long service lives, which makes it the material of choice for stationary storage and GMP facilities. The ABS+ Series (ABS75+, ABS150+) and the long-term storage lines, the BSD+ Series and BSF+ Series, are stainless steel.
In the liquid phase, samples sit directly in LN₂ at –196 °C. Temperature stability is as good as it gets. The drawback: liquid nitrogen can carry microorganisms between leaking sample containers.
In the vapour phase, samples sit above the liquid level in cold nitrogen gas. Contamination risk drops sharply, which is why many biobanks and GMP sites prefer it. What matters then is a shallow temperature gradient from the bottom to the top storage position. Our comparison of vapour phase vs liquid phase storage at –196 °C goes into detail.
Large storage systems come with rectangular or round housings. Rectangular units line up neatly against walls and in rows; round units have a smaller footprint. According to the datasheet, the BSF420+ (rectangular) and BSR420+ (round) have identical capacity and evaporation rate, so the choice follows the room, not the performance.
A model number is a designation, not a volume. For planning, two figures count: vessel volume in litres and sample capacity in your actual format.
The datasheets for the Consarctic® BSF+ Series show how far apart these can be:
Turntable versions such as the BSF420R+ trade some capacity for ergonomics: 20,800 vials instead of 25,900, but every position comes round to the opening. For very large collections, the BSD+ Series scales up to 100,000 cryovials.
Always plan capacity in the real format, with headroom. How racks, cassettes and boxes change the usable number is covered in our article on maximizing cryogenic storage capacity.
Two practical limits also apply. Weight: a full BSF820R+ weighs around 890 kg, which matters for floor loading. Retrieval height: across the BSF+ Series it ranges from 1,170 to 1,355 mm and determines how comfortable daily access is.
A cryogenic freezer's nitrogen use is the sum of static evaporation and operational losses. Static evaporation is what a closed, undisturbed vessel loses per day. It is a design property and appears on the datasheet.
Neck diameter, vacuum quality, insulation and vessel size set the static evaporation rate. Per the datasheet, the BSF220+ evaporates 4.8 litres a day, the BSF420+ 8.3 litres and the BSF820R+ 10.3 litres.
These figures set the hold time: how long the vessel stays at storage temperature without a refill. Hold time is your buffer in a failure scenario, for example when auto-fill or the bulk supply goes down.
A more useful figure than daily loss is loss per stored sample. Converting the datasheet values to 1,000 cryovials shows a clear economy of scale:
The largest vessel holds more than four times as many vials as the smallest but evaporates only about twice as much nitrogen. Consolidating several small freezers into one larger system lowers specific consumption considerably.
On top of static evaporation come everyday losses: lid openings, long retrieval times, frost on the neck, poor refill strategies and transfer-line losses. As the vacuum ages, static evaporation also creeps up. Where these losses arise and how to cut them is explained in reducing liquid nitrogen consumption in cryogenic storage.
An LN₂ freezer does not replace an ultra-low temperature freezer; it complements it. At –80 °C, slow biochemical processes continue in many cells. They effectively stop only below the glass transition temperature of water, around –135 °C. That is why viable cells, stem cells and cell therapies are stored in liquid nitrogen or its vapour phase.
Power is the other difference. A cryogenic tank holds temperature without a compressor, so if the power fails, the hold time remains as a buffer. Our side-by-side of the ULT freezer vs the cryogenic tank shows which system suits which sample type.
For biobanks, ISO 20387 sets requirements for competence, traceability and quality assurance. In GMP environments, every vessel needs installation and operational qualification (IQ/OQ). Consarctic® is certified to EN ISO 13485:2016 and ISO 9001:2015 and performs IQ/OQ with certified technicians for customers in more than 30 countries.
So when choosing a design, think ahead to qualification: sensor positions for temperature mapping, connections for level and alarm monitoring, and clear documentation per vessel.
The right design follows from sample format, access frequency, collection size and room. Frequent access points to a wide neck or an eccentric opening with a turntable. Large, long-term collections point to stainless steel vapour-phase storage. Small, mobile collections point to aluminium.
Compare every series on our page for the Consarctic® cryogenic freezer and storage systems.
It depends on size and design. Per the datasheet, static evaporation across the Consarctic® BSF+ Series ranges from 4.8 litres a day (BSF220+) to 10.3 litres a day (BSF820R+). Operational losses from lid openings, refilling and transfer lines come on top.
Narrow-neck vessels use less nitrogen but make access harder. Wide-neck vessels make it easy to lift whole racks but evaporate more. An eccentric opening with a rotatable bottom combines both: a small opening, full access and up to 30 % less LN₂ consumption.
A cryogenic freezer stores samples at down to –196 °C using liquid nitrogen and needs no compressor. A –80 °C freezer runs on electricity and stays above the glass transition temperature of water (around –135 °C). Viable cells are therefore stored in LN₂ or its vapour phase.
Hold time follows from fill volume and evaporation rate. Large stainless steel systems lose far less nitrogen per sample than small vessels. In routine operation, automatic filling handles refills, and hold time serves as the reserve for failures.
Planning new storage capacity or consolidating existing LN₂ freezers? Talk to the experts at Consarctic®, the market-leading provider of life science cryogenics: we calculate capacity and consumption for your sample format and deliver the right system, IQ/OQ included.