Cryogens Safety

Liquid helium and liquid nitrogen are odorless, colorless, and non-toxic; they are, however, at extremely low temperatures: liquid helium at 4.2K (–452°F) and liquid nitrogen at 77.6K (–320°F). These liquids cause severe burns if they come in contact with skin. Wear protective clothing and gloves that are non-absorbent so that any spillage will run off and not be trapped against the skin.

Contact of liquid cryogens or gas with the eyes can cause severe frostbite. Wear safety goggles or a face shield.

Gaseous helium and nitrogen displace air without warning, and can cause rapid asphyxiation and even death if there is not sufficient ventilation. Always be sure that the oxygen monitor is functioning properly prior to transferring any cryogens. If the alarm mode of the oxygen monitor is activated, immediately determine the cause. If ventilation is a problem, correct the situation. Be sure that the oxygen monitor is reading a safe level before you enter the affected area to continue with service procedures. Always store gas cylinders and cryogen dewars in a well-ventilated area.

Rooms in which cryogen liquids are stored and handled must be designated no smoking areas. The extreme low temperatures of liquid helium and nitrogen cause oxygen from the air to liquify on cold surfaces (e.g., on transfer tubes) and increase its local concentration. There is a potential fire danger if grease or oil come in contact with these surfaces since they are combustible substances.

If you are in the magnet room and a quench occurs follow these basic rules:

  • Remain calm; don't panic.

  • Open the scan room door, prop it open, and exit the room immediately.

  • Turn on the exhaust fan for the scan room (if not automatically turned on by oxygen monitor).

  • If the door cannot be opened, stay near the floor. This is where the oxygen is.

  • Open or, if necessary, break the window to relieve pressure in the magnet room.

  • Prop open the scan room door, and exit the room immediately.

  • If the door cannot be opened, exit through the window.

  • Do not enter the magnet room until the oxygen monitor indicates a safe level.