Liquid nitrogen (LN2) has a temperature of -196°C. On contact with the skin, it causes severe cold burns within fractions of a second, which are comparable in severity to scalds caused by boiling water. Splashes in the eyes can cause permanent damage, and even mere contact with metal surfaces that have been cooled to cryogenic temperatures can lead to immediate freezing of the skin.
Despite these considerable dangers, personal protective equipment (PPE) is treated carelessly in many laboratories. Lab coats instead of cryogenic aprons, thin latex gloves instead of insulated cryogenic gloves, no face visors - such negligence can have serious consequences.
In this article, we explain the essential elements of personal protective equipment for working with cryogenics and liquid nitrogen and provide practical recommendations for safe laboratory practice.
When transferring liquid nitrogen from a nitrogen tank to a cryogenic tank or when filling a dry shipper, there is always a risk of splashes. The low viscosity and the tendency to evaporate violently on contact with warm surfaces make LN2 particularly unpredictable.
Metal instruments that have been immersed in liquid nitrogen - tweezers, cassettes, racks - immediately reach cryogenic temperatures. On contact with unprotected skin, it freezes to the metal surface within milliseconds. The detachment inevitably leads to skin injuries.
Although not a direct injury, oxygen displacement by vaporizing nitrogen is a life-threatening hazard that must be countered not by PPE, but by oxygen monitoring and ventilation.
Cryogenic gloves are the most important protective component. They must meet the following requirements:
A face visor or safety goggles with side protection are mandatory for all transfer operations. Splashes of liquid nitrogen in the eyes can lead to corneal damage and, in the worst case, blindness. Standard laboratory goggles without side protection do not offer sufficient protection.
A special cryogenic apron protects the upper body and thighs from splashes. Ideally, the apron is made of a material that does not absorb LN2 but allows it to roll off.
Open shoes, sandals or shoes with a fabric surface are absolutely inadmissible in a cryo lab. Closed, waterproof safety shoes prevent spilled nitrogen from penetrating into the shoe and vaporizing there - a particularly treacherous scenario, as vaporization inside the shoe leads to severe burns before the person affected can react.
Even the best protective equipment is of little use if it is not used correctly. Regular training is therefore essential:
In Germany, the rules of the employers' liability insurance association (BGR) and the Industrial Safety Regulation govern the handling of cryogenic substances. The employer is obliged to carry out a risk assessment and provide the necessary PPE. The costs for the PPE are borne by the employer.
Consarctic® not only offers cryogenic products and cryogenic systems, but also provides its customers with comprehensive advice on laboratory safety. Our consulting services include the recommendation of suitable PPE, the integration of oxygen monitoring systems and the development of laboratory-specific safety protocols.
If you need advice on how to safely equip your cryo lab, contact our experts for a comprehensive safety concept that reliably protects your employees.