Everything UK Laboratories Need to Know About Liquid Nitrogen: A Practical Guide

Liquid nitrogen (LN2) is one of the most widely used substances in modern science, healthcare, and industry - and one of the least understood in terms of the operational and safety detail that actually matters day to day.

This guide covers the essentials for anyone working in or managing a UK laboratory environment where LN2 is stored, handled, or used.

What is liquid nitrogen?

LN2 is nitrogen gas that has been cooled to -195.8°C, the temperature at which it condenses into a clear, colourless liquid. It is produced industrially from atmospheric air - nitrogen makes up around 78 per cent of the air we breathe - through a process of compression, cooling, and fractional distillation. The result is a cryogenic liquid that is non-toxic, non-flammable, odourless, and chemically inert at normal temperatures.

What makes LN2 uniquely useful is its ability to maintain a stable temperature of -195.8°C passively, without any power source or mechanical system. A good quality vacuum-insulated dewar left in a laboratory will hold its contents at cryogenic temperature for weeks or months.

Why does -195.8°C matter for biology?

The biological threshold for cryopreservation is approximately -130°C. Below that point, cellular metabolism stops completely. Enzymatic activity ceases. Biological material enters a state where deterioration effectively does not occur. Liquid nitrogen provides a 65°C safety margin below that threshold, which is what makes it the standard storage medium for embryos, oocytes, sperm, stem cells, tissue samples, and other biological material requiring long-term preservation.

How is it supplied to UK laboratories?

UK labs receive LN2 either via bulk tanker delivery to a fixed on-site tank (suited to high-volume users) or through scheduled cylinder and dewar delivery (the standard model for smaller labs and fertility clinics). The supply model choice directly affects operational risk. A lab receiving weekly deliveries needs enough capacity to cover that interval plus a buffer for delays, particularly over weekends and public holidays when emergency deliveries are typically unavailable.

What drives the price of liquid nitrogen?

LN2 pricing varies by volume, delivery geography, purity grade, and the evaporation performance of the storage vessel. Bulk supply is cheaper per litre but only cost-justifiable above roughly 500 to 800 litres per month. The vessel's evaporation rate is a frequently overlooked cost factor - a dewar losing more LN2 per day adds up significantly over its operational life.

The four hazards you must manage

Cryogenic burns from direct skin or eye contact, asphyxiation from LN2 vapour displacing oxygen in enclosed spaces, pressure explosion from ice plugs or unsealed containers, and oxygen enrichment near cold surfaces are the four hazard categories that govern safe LN2 handling. Each requires specific controls. Together they require a formal risk assessment under UK health and safety regulations.

The HSE's oxygen depletion threshold is 19.5 per cent. LN2 expands to approximately 694 times its volume when it evaporates, meaning even a small spill in a confined space can reach that threshold rapidly and without any sensory warning.

Key UK regulations

The Management of Health and Safety at Work Regulations 1999, Manual Handling Operations Regulations 1992, Pressure Systems Safety Regulations 2000, and BCGA Code of Practice CP30 (Revision 3, 2019) are the primary regulatory and code documents governing LN2 use in UK laboratories.

For LN2 storage vessels, safety equipment, and laboratory consumables in the UK, Cryolab has been supplying IVF clinics, NHS units, and research laboratories for over 40 years. Visit cryolab.co.uk for the full range.