Almost every area where liquid nitrogen is used has a number of warning signs or stickers. “Danger,” “do not touch,” “extreme cold,” or “personal protection required. It sounds fierce, but is liquid nitrogen actually that dangerous?
In this blog, we look at the safety and danger of liquid nitrogen. We look at safety measures and explain how Demaco contributes to the efficient use of this substance.
What is liquid nitrogen?
Liquid nitrogen is a clear, colorless liquid with a very low temperature of -196°C at atmospheric pressure. The liquid has a relatively high density of about 807 kg/m³ and is inert. Therefore, under normal conditions, liquid nitrogen does not react with most other materials.
Because of its extreme cold and wide availability, liquid nitrogen is used in a hefty list of industries. Examples include the food industry for freezing food, the pharmaceutical industry for freezing and preserving biological materials, the medical world for various treatments and scientific research as a refrigerant.
The dangers of liquid nitrogen
Despite its many useful applications, liquid nitrogen also carries a number of risks. Namely, if extreme cold is not handled properly, it can affect its application and the health of its users.
Here are the main dangers of liquid nitrogen:
- Injury from extreme cold: When (the cold vapor of) liquid nitrogen comes into direct contact with the skin, it can cause frostbite and severe burns. Wet skin in particular freezes at lightning speed, and sensitive tissue such as that of the eyes is quickly damaged. Even a brief exposure can have permanent consequences.
- Explosion by high pressure: Does liquid nitrogen heat up? Then it becomes gaseous and expands at a ratio of 700:1. In other words; gaseous nitrogen requires 700 times more space than liquid nitrogen – and there usually isn’t any in an infrastructure, tank or container. Therefore, if the pressure rises too high, an explosion can occur.
- Suffocation and oxygen displacement: Liquid nitrogen can displace oxygen upon evaporation and create an oxygen-deficient environment. Especially in small and poorly insulated spaces, a lack of oxygen can lead to unconsciousness and eventually even death. The shortness of breath often strikes suddenly, without obvious warning.
Is liquid nitrogen flammable?
So while liquid nitrogen poses several dangers, the substance has one advantage: by itself, liquid nitrogen is not flammable. As an inert substance, the cryogenic liquid does not react with most other materials under normal conditions. The same is true of nitrogen gas. In fact, should you hold a flame in a cloud of nitrogen gas, it will extinguish because nitrogen displaces oxygen.
Safety precautions when handling liquid nitrogen
Given the potentially serious dangers posed by liquid nitrogen, it is important to establish and follow strict safety protocols when using this substance. Here are some important safety precautions to follow when using liquid nitrogen:
- Personal Protective Equipment: For optimal protection, most sites use a face shield, safety glasses, insulated cryogenic gloves and protective clothing that covers the entire skin. Gloves should be loose so that they can be removed quickly when in contact with liquid nitrogen. In fact, cryogenic gloves provide protection against cold nitrogen in gaseous form coming off a cryogenic liquid, but cannot withstand prolonged contact with the liquid itself.
Adequate ventilation: Storage and use facilities where liquid nitrogen is used should be adequately insulated to prevent the displacement of oxygen present in the air. These rooms should also be equipped with a proper oxygen meter, which will indicate in time when there is too little oxygen in the room. This may indicate a leak in the liquid nitrogen infrastructure. This puts users at risk and wastes liquid nitrogen.
- Quality enhancing products: Products such as a degasser and an automatic gas vent ensure that excess gas in a system is evacuated and that an application always remains filled with high-quality cold liquid nitrogen. This is not only important for the application, but also reduces the risk of pressure build-up and a possible explosion.
- Safe storage and transportation: Isolation is central to the storage, transportation and application of liquid nitrogen. The better the insulation, the less gas formation and pressure buildup. The best insulation for liquid nitrogen infrastructures is vacuum insulation. This insulation method uses a double concentric tube construction with a vacuum in between that allows almost all heat losses to be kept out of a system.
At Demaco, we fit almost all of our products and projects with vacuum insulation. Would you like to know more about this insulation technique? Then read on to our pages about vacuum technology and the 10 advantages of vacuum insulated systems.
- Emergency procedures and training: All employees working with liquid nitrogen must be trained in handling the substance. They should be aware of the hazards and be able to follow emergency procedures. These should include clear steps to follow when, for example, a leak occurs, a person is injured, or an alarm goes off for oxygen deprivation in an enclosed space.
Regulations and (inter)national standards
Following rules around the use of liquid nitrogen is not only important, it is also required by various agencies. There are both national and international standards for the use of hazardous substances, and liquid nitrogen, because of its extremely low temperature, is one of them.
The regulations surrounding hazardous substances are designed to ensure both the safety of individuals working with the substance and public health.
Here are the main rules governing the safety of liquid nitrogen:
- Local and national regulations: Each country has specific regulations for handling hazardous materials, including liquid nitrogen. These can range from detailed safety protocols to transportation and storage requirements. In the United States, for example, regulations for the use of liquid nitrogen fall under the Occupational Safety and Health Administration (OSHA), while in Europe guidelines are often determined by both national laws and EU directives.
In the Netherlands, the Working Conditions Decree is primarily responsible for the use and application of liquid nitrogen. This decree sets specific requirements for working safely with hazardous substances to ensure the health and safety of workers. Examples include clear guidelines for personal protective equipment, prevention of freezing injuries, and safe storage and transport regulations. The Ministry of Social Affairs and Employment (SZW) conducts checks on companies’ compliance with these rules.
International standards: Organizations such as the International Organization for Standardization (ISO) provide standards that help ensure safety during the use of liquid nitrogen. To obtain ISO certification, an organization must undergo rigorous external audits to prove that all processes and systems used meet the specific requirements of the particular ISO standard.
At Demaco, our products and services are certified to the ISO 9001 standard for quality management systems. This is an important certification for the safe use of cryogenic gases such as liquid nitrogen, liquid hydrogen and more.
Specific industry standards: Depending on the industry, additional standards may apply that regulate safety around the use of liquid nitrogen. This is especially true in industries where hygiene is important, such as the food industry, pharmaceutical industry and medical institutions.
For example, in drug production in the pharmaceutical industry, liquid nitrogen systems must be regularly inspected and cleaned and employees must wear protective clothing to minimize exposure to extremely low temperatures.
Demaco’s infrastructures for liquid nitrogen
At Demaco, we specialize in designing and building infrastructures for liquefied gases such as liquid nitrogen, liquid hydrogen, liquid helium, LNG and more. We are committed to making the transportation and application of these cold liquids as efficient as possible, and of course safety is part of that. We do this in the following ways, among others.
- Optimal insulation (vacuum): Demaco uses advanced vacuum isolation technologies to set up infrastructures for liquid nitrogen as safely as possible. For example, we supply vacuum insulated transfer lines, cooling trays and filling stations for liquid nitrogen, including the corresponding quality improvement products to provide an infrastructure with all safety requirements.
- Customized projects: Demaco delivers customized solutions. From design to implementation, we think through each project together with the client. We look at the location, consider all safety guidelines and only deliver products that both we and the customer fully support. With years of experience, we know the dangers of liquid gases like no other, and we do everything we can to minimize them.
- Guidelines and certifications: Our infrastructure and processes are designed to meet all major national and international safety standards and guidelines. Some examples of our certifications include ISO 9001 and VCA** quality and safety certificates, ISO 3834-2 for welding technology, and PED modules H and H1 (according to EU directive). By adhering to all guidelines, we know that we supply only the very safest products.
- Installing pressure relief devices: This prevents the pressure in systems from rising too high, minimizing explosion hazards.
- Conditioning equipment: We use advanced techniques to evacuate excess gas and prevent pressure buildup.
- Vacuum insulation: The use of vacuum insulation helps prevent burns caused by extreme cold and ensures optimum safety during transportation and storage.
- Temperature protection on blow-off lines: This system prevents pipes from unsafe heating and pressure build-up.
- Calamity-controlled valves: These valves ensure quick and efficient intervention in the event of an emergency to avoid further risks.
