Cryogenics Hazards

Frostbite

Cold vapours or gases from liquefied atmospheric gases may cause frostbite given prolonged or severe exposure of unprotected parts. A symptom is local pain which usually gives warning of freezing but sometimes no pain is felt or it is shortlived. Frozen tissues are painless and appear waxy, with a pale yellowish colour. Thawing of the frozen tissue can cause intense pain. Shock may also occur.

The immediate treatment is to loosen any clothing that may restrict blood circulation and seek immediate hospital attention for all but the most superficial injuries. Do not apply direct heat to the affected parts, but if possible place in lukewarm water. Sterile dry dressings should be used to protect damaged tissues from infection or further injury, but they should not be allowed to restrict the blood circulation. Alcohol and cigarettes should not be be given.

Effect of cold on lungs

Transient exposure to very cold gas produces discomfort in breathing and can provoke an attack of asthma in susceptible people. Prolonged inhalation of very cold vapour or cold gas, whether respirable or not, is unlikely to produce damage to lungs unless the temperature is so low that the mouth and nose are frostbitten

Hypothermia

Low air temperatures arising from the proximity of liquefied atmospheric gases can cause hypothermia and all people at risk should be warmly clad. Hypothermia is possible in any environment below 10°C but susceptibility depends on length of exposure, atmospheric temperature and, not least, the individual; older people are more likely to be affected.

The symptoms of hypothermia are:

1. A slowing down of physical and mental responses
2. Unreasonable behaviour or irritability
3. Speech or vision difficulty
4. Cramp and shivers

People apparently suffering from hypothermia should be wrapped in blankets and moved to a warm place. Seek immediate medical attention. No direct form of heating should be applied except under medical supervision.

Preventative Measures

Protective Clothing

Protective clothing is only intended to protect the wearer handling cold equipment from accidental contact with liquefied atmospheric gases or parts in contact with it.

Non-absorbent leather gloves should always be worn when handling anything that is, or has been recently, in contact with liquefied atmospheric gases.

The gloves should be a loose fit so that they can easily be removed if liquid should splash onto, or into, them.

It is essential that clothing is kept free of oil and grease where oxygen is in use.

If clothing becomes contaminated with liquefied atmospheric gases or vapour, the wearer should ventilate it for a minimum of five minutes whilst walking around in a well ventilated area. With oxygen the risk is of rapid burning of the material; the ignition source may be tiny- a spark or a piece of burning tobacco-and so in these circumstances it is essential to keep away from any such source of ignition.

Woven materials are best avoided but, if they are used for protective clothing, it is essential to ensure that they do not become saturated with cold liquid.

Goggles, or face shield, should be used to protect the eyes and face where spraying or splashing of liquid may occur.

Overalls, or similar clothing should be worn. These should preferably be made without open pockets or turn-ups where liquid could collect and should be worn outside boots.

Warning Signs