Cryogens

A cryogenic liquid is defined as a liquid that has a normal boiling point below -240°F (-150°C, 123 K). The most commonly transported, handled, and stored industrial gases in their liquid state at cryogenic temperatures include argon, helium, hydrogen, nitrogen, and oxygen. Due to the extremely low temperatures and the high rates at which cryogenic liquids convert to gas, it is essential to observe several general safety precautions and practices. Additionally, specific precautions must be taken when dealing with a particular cryogenic liquid, especially if it may react with contaminants or pose other hazards, such as asphyxiation or flammability.

Users should always have and be thoroughly familiar with the Safety Data Sheet (SDS) for their specific product. All operators must be well-acquainted with the instructions provided for the equipment used with cryogenic liquids.

Hazards

• Extreme Cold: Can cause immediate and severe frostbite to exposed skin or eyes.
• Asphyxiation: Can rapidly displace oxygen, particularly in poorly ventilated areas.
• Expansion: Cryogenic liquids, such as liquid nitrogen, can expand up to 700 times when transitioning from liquid to gas. Rapid temperature changes can lead to tank or vessel explosions.

Minimum Personal Protective Equipment (PPE)

The required apparel and PPE for handling cryogenic liquids include:

• A full face shield over safety glasses
• A long-sleeve shirt or lab coat
• Loose-fitting thermal insulated or leather gloves (these should not be confused with heat-resistant gloves)
• Pants without cuffs to prevent liquid from becoming trapped against the skin
• Closed-toe shoes that fully cover the feet.