Cryogenic fluids

Cryogenic substances are substances that are in an extremely cold state. Contact with the substance or with materials cooled with the substance may cause injuries that are similar to burns. The substance may also cause asphyxiation in a closed room, as it can displace the oxygen in the room when in gaseous form.

In order to avoid such dangers, it is necessary to take the following safety measures, for example:

Risks:

Cryogenic fluids are generally used as a cooling agent. The most common ones are liquid nitrogen, with a boiling temperature of -196°C at a pressure of 1 bar, and mixtures of dry ice (solid CO2) and a solvent. Liquid helium, oxygen and carbon dioxide are also used in laboratories. Working with cryogenic fluids directly or indirectly involves health hazards. Contact with the skin causes 'burns', contact with the eyes can cause severe damage. Another hazard associated with cryogenic fluids is their toxicity. Toxicity is usually rather low and any damaging effects will therefore only occur if one is exposed to a high concentration (high volume percentage in the air). Large quantities can, however, be produced easily: one litre of liquid nitrogen will, after it has vaporized, turn into around seven hundred litres of gaseous nitrogen.

Cryogenic fluids can, after they have vaporized, displace oxygen from the air. So a quick vaporization (for example, caused by a flask falling over) could therefore result in asphyxiation. As the cold gases accumulate on the floor, you will, at first, not notice anything. However, if a person becomes unwell in the relevant room due to a lack of oxygen and falls, the risk of asphyxiation will be very high. That is why it is forbidden to leave containers inside small, poorly ventilated spaces (a lift, for example), with someone present there.

Some cryogenic fluids require even more attention due to fire risks. This requires little explanation when it comes to liquid hydrogen. The temperature of liquid nitrogen or helium is lower than the boiling point of oxygen. As a result, oxygen from the air could condense into these fluids. Liquid oxygen is very dangerous, as it causes violent and often explosive reactions with a great many materials. The combination of liquid oxygen spilled on clothes and an (electrostatic) spark could cause the clothes to catch fire immediately. The use and creation of liquid oxygen should therefore be avoided as much as possible.

Instructions for use:

In general, the following regulations apply:

Contact the Health, Safety and Environment Coordinator when in doubt or when working with cryogenic fluids for the first time. Never perform this work alone.

Regulations on transport:

First aid:

In case of any accidents with cryogenic fluids involving persons, the following rules apply: