Moving liquid nitrogen dewars and cryogenic freezers

Why a full dewar is not moved

Liquid nitrogen is extremely cold, around minus 196 degrees Celsius. A dewar that falls or spills can cause cold burns, and its vapour displaces oxygen in an enclosed space such as an elevator or a truck cab. So nitrogen dewars are moved empty, and the nitrogen itself is handled by a licensed supplier.

What happens to the samples

The lab moves the samples separately, usually in a dedicated dry shipper. This is a dewar that absorbs the nitrogen and keeps a cryogenic temperature for a long time, with no free liquid that can spill. The sample schedule is planned with the lab manager, so the dewar at the new site is already filled and cold when they arrive.

Before the move

• The licensed supplier empties the nitrogen from the dewars and freezers, or the lab lets it evaporate according to its procedure.
• The lab takes out the samples and transfers them to the shipping dewars.
• Fill lines, controllers and sensors are disconnected, and every connection is labelled.
• Refilling at the new site is arranged with the supplier, on moving day or right after it.

Transport

• A nitrogen dewar is built with vacuum insulation, and a knock or a fall can damage the insulation. So it travels upright, on a suitable trolley, strapped and padded.
• A large cryogenic freezer travels like a minus 80 freezer: upright, strapped and in a truck with shock absorbers.
• Doors and elevators are measured in advance, because cryogenic freezers are heavy and wide.

At the new site

The dewars and freezers are placed in a ventilated location planned for them, not in a small closed room. The supplier refills them, the lab checks that the dewar holds its cold as usual, and only then returns the samples.

Customer responsibilities

Disconnecting and connecting gas, water and power, instrument calibration and biosafety cabinet certification are done by the customer's technicians or contractors. If needed, we are happy to refer you to a qualified technician we know.

More about freezers and the cold chain

• Moving a −80 °C freezer without losing samplesHow to move a −80 °C ultra-low freezer: plan the samples, use dry ice, transport upright, wait before switching on and verify temperature after the move.
• Moving a CO2 incubator: preparation, transport and start-upHow to move a CO2 incubator: disconnect gas, empty the water pan, decontaminate, transport upright and restart with stabilisation before returning cultures.

More guides

• Moving a −80 °C freezer without losing samplesHow to move a −80 °C ultra-low freezer: plan the samples, use dry ice, transport upright, wait before switching on and verify temperature after the move.
• Moving a CO2 incubator: preparation, transport and start-upHow to move a CO2 incubator: disconnect gas, empty the water pan, decontaminate, transport upright and restart with stabilisation before returning cultures.