Dry ice is made from liquid carbon dioxide by reducing pressure and temperature in a controlled manner. This converts liquid carbon dioxide into clean, white and low-temperature carbon dioxide snow. The snow is then compressed under high pressure to form blocks or pellets.
Dry ice has a temperature of -79 °C. When the temperature rises, dry ice sublimates from solid form directly to gas without passing through a liquid phase.
Characteristics of dry ice:
- Flavourless and odourless
- No residue, thanks to sublimation
- Germ and bacteria-free
- Non-poisonous
- Non-flammable
- Easy to control because heavier than air
- Requires no electricity on-site when used for cooling
- More than three times colder than water ice
Dry ice is used extensively to refrigerate dairy, meat, frozen and other perishable food products during transportation. It is also used as a cooling agent in varied industrial processes such as grinding heat-sensitive materials, shrink fitting and vacuum cold traps. Dry-ice pellets are used for dry-ice blasting when cleaning varied machinery and motors. Dry ice passing to gas can even be used to produce fog-like theatrical effects.
Carefully study instructions for safety before handling dry ice.