Liquid Nitrogen: Uses & Safety Measures

 Liquid nitrogen, known for its ultra-low temperature, can pose considerable risk if mishandled. A notable incident took place at a poultry plant in Gainesville, Georgia, where a liquid nitrogen leak led to six fatalities and nearly a dozen injuries, as reported by the Associated Press. 

Liquid nitrogen, what is it and what makes it hazardous?

Understanding Liquid Nitrogen and its Applications:

Nitrogen, a key component of life on Earth, constitutes approximately 78 percent of our atmosphere. Discovered by Daniel Rutherford in 1772, this element is crucial for plant growth. When its temperature drops to -195°C, nitrogen transitions into a liquid state. 

The first successful liquefaction of nitrogen was achieved by Polish professors Zygmunt Wróblewski and Karol Olszewski in 1883. A mere 15 years later, James Dewar, a British scientist, developed a storage container that laid the foundation for modern liquid nitrogen (LN2) vessels.

Liquid nitrogen, owing to its freezing properties, is frequently used as a refrigerant in various industrial cooling systems, such as those used in the Foundation Food Group facility. The medical industry also relies on it for storing blood and reproductive cells, in addition to its use in research laboratories and the food industry for refrigeration.

Pioneering British culinary expert Agnes Marshall, often referred to as the "Ice Queen" by her Victorian London peers, is believed to have introduced the use of liquid nitrogen in cooking. High-end restaurants that specialize in molecular cuisine often use small quantities of liquid nitrogen to instantly freeze food and enhance cocktails. However, it's important to remember the potential risks, as highlighted by an incident where a British teenager required stomach removal surgery after consuming a cocktail containing liquid nitrogen.

The Dangers of Liquid Nitrogen:

Despite its widespread use as a coolant, improper handling of liquid nitrogen can lead to fatal consequences. When liquid nitrogen leaks into the air, it transforms into a colorless, odorless gas that displaces oxygen in confined spaces.

In particular, leaks like the one at the Food Group Foundation poultry plant can be extremely treacherous. When liquid nitrogen is heated, it vaporizes and expands, leading to a nitrogen gas cloud that can deplete oxygen in poorly ventilated rooms. Oxygen deficiency can result in headaches, dizziness, unconsciousness, confusion, and even suffocation. Given that the gas is odorless, colorless, and inert, leak warning signs are often absent, leading many to succumb to their symptoms before understanding the situation.

Cryogenic accidents are sadly not uncommon. The U.S. Occupational Safety and Health Administration (OSHA) reports that between 2012 and 2020, 14 people lost their lives due to suffocation in incidents involving liquid nitrogen.

Long-term exposure of liquid nitrogen to bare skin can cause tissue damage. However, the Leidenfrost effect, as explained by the Royal Institution, can somewhat prevent cryogenic burns. 

Liquid nitrogen, with its high liquid-to-gas expansion ratio of 694, can lead to disastrous consequences if it vaporizes within a closed container. A case in point is a 2006 incident at Texas A&M University, where a liquid nitrogen tank was propelled through the ceiling of a lab, much like a rocket. Thankfully, no injuries were reported.