Ensuring Safety in Cryogenic Transportation

Cryogenic liquids, such as liquid nitrogen and liquid oxygen, are gases condensed into a liquid state and play pivotal roles in various industries, such as medical, oil and gas, and even space exploration. Most of the products that we deliver are pulled from the atmosphere using air separation units, but any gas can be liquefied at the right temperature and pressure. The extreme temperatures of cryogenic liquids pose significant safety risks during handling. In this article, we dig into essential safety measures and best practices to mitigate these risks during transportation, loading, and unloading to ensure a secure working environment.

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Understanding the Hazards 

Cryogenic liquids are characterized by their extremely low temperatures and high expansion ratios. When I was first training for cryo, I was amazed by how quickly a liquid nitrogen leak freezes the floor of a trailer and how violently it boils on the ice. Exposure to these substances can cause frostbite and cryogenic burns, leading to severe tissue damage.Additionally, the displacement of oxygen by cryogenic vapor poses a risk of asphyxiation in enclosed spaces. Moreover, the rapid vaporization of cryogenic liquids can result in over-pressurization and potential explosions. If a cryogenic liquid gets trapped in a vessel without a safety device, it will explode like this dewar that had its safety replaced with brass plugs.

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Pre-trip Safety Procedures

Before you go to the loading station, you should:

• Take an inventory of required tools, gaskets, trailer seals, and PPE
• Locate the previous CofA
• Know if it is medical or industrial grade
• Know what grade of product you will be loading
• Know if there is a balance
• If not, know how long it has been empty, and if you’ll be loading a hot trailer
• Know if you are going to a managed or DIY loading station
• Discuss any distressing abnormalities with dispatch

When picking up an unfamiliar piece of equipment, it’s best to go through it with a fine-toothed comb. In addition to the standard pre-trip inspection, you should:

• Check the pony motor fuel level, belt tension, wear, and general operability
• Study the cold-cabinet
• Check all the markings and valve tags
• Trace and understand the plumbing
• Check the operation of the pressure and level gauges, if possible, and try to locate the fill level marked by other drivers for loading without a scale, so you have a general idea when you are full
• Double-check the pressure relief safety devices
• Understand how the fire block valve works, if so equipped
• Understand how the emergency shutdown system works, if so equipped
• How would a DOT inspection go?

If your trailer is flat, with extremely low or no pressure, it may need to be purged back into service. At a managed loading station, the operator would probably give you a pressure shot in order to take a pre-load sample. Make sure to communicate with the carrier about what is required to get the trailer into service before loading, or you could end up with field-grade product.

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Loading/Unloading Safety Considerations

First off, trick yourself out in all that sweet PPE. If you are unfamiliar with the loading/customer station or procedure, ask LGT dispatch if they can put you in contact with another driver who is familiar with the system. Otherwise, get some tips from operations or a local driver. Before starting, replace the gasket, if necessary, secure the fill line connection, and follow the local fill/customer station procedure. As a side note, until both sides of the connection and the gasket cool down to the same temperature, it will usually leak a little. Itwon’t stop leaking until it is cold.

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Emergency Preparedness

Effective emergency procedures are vital in mitigating the consequences of accidents. Prompt detection and response to leaks, coupled with adequate fire safety measures, are paramount. Additionally, training in medical emergencies, including cryogenic burns and asphyxiation, equips personnel to respond effectively to unexpected situations.

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Conclusion

Safe handling of cryogenic liquids is critical for your health and safety. By developing a good standard operating procedure and holding oneself to a high personal standard, one can mitigate risks and ensure a secure working environment. Vigilance, compliance, and a commitment to continuous improvement are essential for safeguarding against potential hazards.