Nitrogen Tank or Cryogenic Dewar? Not Sure Where they ...

Liquid nitrogen is used in a broad range of industries, from steelmaking and pharmaceutical to health care and ceramics. The inert gas is also used in laboratories, breweries, fine cooking, and more. Wherever liquid nitrogen is used, it must be stored securely so as not to mingle with air. Learn why nitrogen must be so carefully contained and where and how N2 gas is stored.

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Bulk Nitrogen Tank Storage 

Liquid nitrogen is stored in a bulk nitrogen tank, also known as a nitrogen dewar. Nitrogen dewars exist wherever nitrogen is used, including in:

• Labs
• Research universities
• Restaurants, bars, and hotels
• Freezers
• Hospitals
• Flash freezing facilities
• Food processing facilities
• Cryotherapy facilities
• Manufacturing plants

The nitrogen dewar features a vacuum stopper, which protects the substance inside and prevents the nitrogen from boiling off. Dewars must have pressure release valves to prevent a bulk nitrogen tank explosion, which can occur when pressure builds up inside the tank. Since liquid nitrogen vaporizes at room temperature, it&#;s critical that the tank stay sealed at all times.

Nitrogen and other insert gases, including argon, displace air when they are released into the environment. As oxygen is displaced, the air becomes oxygen deficient. Breathing oxygen deficient air causes respiratory distress and death via asphyxiation. Since nitrogen is colorless and odorless, there is no way to tell that a leak occurs unless you use an oxygen monitor, which samples oxygen levels.

Given the risks posed by the material, bulk nitrogen tanks must be stored and transported safely and securely. Workers must bleed out pressure before transporting the tanks, for example, to reduce the risk of incident during transport.

A robust ventilation system should be installed where the nitrogen is kept, so escaped nitrogen can be vented away, and fresh air should be circulated into the storage room several times per hour.

Other safety measures include checking that fittings are appropriate, wearing gloves to prevent the nitrogen from burning the skin, and never filling dewars more than 80 percent full.

While liquid nitrogen can be transferred from the bulk nitrogen tank into a smaller tank for small scale use, it must only be transferred into approved container. If you use the wrong container, it could shatter, leaking nitrogen into the air and decreasing available oxygen.

Wherever nitrogen is stored or used, signs warning of the risks associated with the material should be posted as a warning to employees. When working with nitrogen, staff should wear eye protection, cryogenic gloves, and other safety equipment.

Anyone who handles or works with the gas should be trained in safe use, storage, and handling of bulk nitrogen tanks as well. The valves, gauges, and other components of the nitrogen storage tank should be inspected regularly for safety, and replaced whenever you notice wear and tear.

Why You Need an Oxygen Monitor Where Nitrogen is Stored

By placing an oxygen monitor wherever nitrogen is used, you can protect worker safety and prevent injury or fatality onsite. Oxygen monitors continually sample oxygen levels in the room, making sure that oxygen falls within acceptable levels. Should nitrogen gas leak from the dewar, ambient oxygen levels will start to tumble as the air is displaced by nitrogen.

When oxygen levels fall to the threshold set by OSHA, which is 19.5 percent, the oxygen deficiency monitor will sound and flash alarms to notify workers onsite. Staff can exit the room before they begin to experience the adverse effects of being in an oxygen deficient atmosphere, then call 911 so emergency personnel can respond to the threat.

PureAire offers a robust oxygen deficiency monitor capable of withstanding low temperatures of -40 Celsius. Once installed, the oxygen monitor works as intended for 10+ years with no annual maintenance or calibration. An ultra-loud alarm is audible throughout the premises, while a flashing light provides a secondary alert for employees. The unit easily mounts on the wall with brackets and comes with a 3-year warranty. Learn more about oxygen monitors from PureAire at www.pureairemonitoring.com.

Cryogenic tanks are an essential part for many industries, as they are a key element to store certain gases crucial for diverse processes. In light of such importance, we take a look at the different possibilities in the current cryogenic tanks market and provide 4 key questions to answer before acquiring a cryogenic container.

Use and utility of cryogenic tanks

Cryogenic tanks are a type of industrial storage tank ideal for situations where large quantities of gas need to be stored in liquid form.

They are the right solution to store substances such as Liquid Oxygen, Liquid Nitrogen, Argon, C02, LNG, LPG, Liquid Hydrogen, etc, all of which must be stored at very low temperatures in order to maintain their properties. Thus, it&#;s common to hear of a cryogenic oxygen tank, a LNG cryogenic tank, and so forth.

As more and more industries require the gases mentioned above, demand for cryogenic tanks keeps growing and is projected to grow at a higher rate than 5% CAGR between and . 

The main characteristics of an adequate cryogenic storage tank include:

• They&#;re versatile, provide an optimal internal distribution and thus optimize resources. They allow for the installation of a centralised network for the optimal distribution of the different cryogenic gases used, so that there is no gas return to the plant
• Improved loading process through the use of vaporisers, so that the liquid gas passes directly from the production plant to the user, avoiding sudden movements and improving stability and safety.
• Higher purity than other storage systems, as the gas remains isolated in a hermetically sealed tank so that the possibility of contamination with any external agents is minimized.
• Because they&#;re hermetically sealed, they remain stable and thus are safer than other storage alternatives. Also, as the cylinder transfer within the facilities is avoided, unnecessary risks aren&#;t taken.

For more information, please visit What Is a Dewar Tank?.

Related content: Cryogenic dewar: tips for a safe, optimized storage

Types of cryogenic tanks

The structure for cryogenic tanks is made of three parts:

• An inner vessel made of stainless steel and designed to withstand very low temperatures.
• An outer vessel made of carbon steel. In order to guarantee cryogenic temperatures and safety, these two vessels are insulated from each other by a combination of materials that provide such insulation.
• In addition to these two containers, a cryogenic storage tank is also equipped with a pressure regulation system, which is specifically designed to ensure that the cryogenic tank always operates at a constant pressure. At the same time, this pressure is set with the user&#;s needs in mind.

While cryogenic tanks have this basic structure in common, it&#;s possible to distinguish between two types of cryogenic container: 

• Flat-bottom cryogenic tanks, such as the flat-bottomed tanks Cryospain has recently installed in the USA.
• Large vacuum-insulated cryogenic pressure vessels, such as the new vacuum insulated vessels Cryospain has generated in collaboration with IDESA, which allow for large-scale cryogenic storage.

How to choose a cryogenic container?

Depending on the substance to be stored

When choosing cryogenic tanks, companies must consider what substances they need to store, and communicate it to the tanks manufacturer. 

Different substances will require a different tank shape and design, so that it perfectly adapts to the cryogenic liquid it will need to store. 

Some common substances that require a cryogenic container include: 

• LIN (liquid nitrogen) 
• LOX (Liquid Oxygen) 
• LAR (Liquid Argon) 
• CO2 (Carbon Dioxide) 
• LNG (Liquefied Natural Gas)
• LHe (Liquid Helium)
• LH2 (Liquid Hydrogen)
• LPG ( Liquefied Petroleum Gas) 
• Liquid Ethylene

Depending on the size

Different companies will be in need of different tank sizes, depending on their substance demand and use, among other factors. At Cryospain we are specialized in tanks for large quantities >500 m3

Depending on the material

Stainless steel and carbon steel are the main two materials for building cryogenic tanks. At the same time, different insulating materials can be used: from cellular glass, to rockwool and expanded perlite. Thus, each project must be studied separately, in order to ensure the right materials are used. 

Other considerations

Other criteria to pick the right cryogenic tanks can include: 

• The need to comply with national and/or international regulations.
• The geographical location where the tanks will be installed. For instance, seismic criteria must be considered. The difficulty to access the are might also present a challenge, like it did when Cryospain built a flat-bottom cryogenic tank in Santa Cruz, Bolivia.

Keep reading: Everything you need to know when choosing cryogenic tanks for gas storage

At Cryospain we develop custom flat-bottom cryogenic tanks, as well as large vacuum-insulated cryogenic pressure vessels, all according to our clients&#; needs as well as international and local regulations.

We are in charge of designing these cryogenic tanks from the first sketches  through to construction and commissioning, coordinating our design, engineering and production teams. 

In order to take into account our clients&#; needs and to guarantee a smooth implementation, we provide a careful design process through computer-aided systems, which provide virtual simulations of the future cryogenic tanks.

Thus, as part of the cryogenic tanks market, we generate tailored cryogenic storage solutions, designed and built by our experts. Want to learn more about cryogenic tanks and how to pick the right one for your business? Get in touch with us. 

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