What is Dry Ice?


Dry ice is frozen carbon dioxide, a normal part of our earth's atmosphere. It is the gas that we exhale during breathing and the gas that plants use in photosynthesis.
 
Dry ice is particularly useful for freezing, and keeping things frozen because of its very cold temperature which is -109.3^oF or -78.5^oC.
 
Dry ice is widely used because it is simple to freeze and easy to handle using insulated gloves. Dry ice changes directly from a solid to a gas (known as sublimation) in normal atmospheric conditions without going through a wet liquid stage. Dry ice doesn't "melt" into a liquid state!
 
The sublimation rate of dry ice is generally five to ten pounds every 24 hours in a typical ice chest. Sublimation begins immediately upon creation of the dry ice. 
Dry ice sublimates faster than regular wet ice melts but will extend the life of regular ice if placed in the bottom of a cooler with the wet ice on top.  Be sure to place a plastic or paper barrier between the dry ice and wet ice so as to never accidentally select dry ice when the intention was to select wet ice.  It will also deep-freeze your wet ice, more so if it is in contact with the wet ice.  You may end up with a super-cold-extra-frozen heaping of wet ice that you can't break up with an ice pick very easily!
 
Do not store dry ice in your freezer. The extreme cold of dry ice will cause your freezer's thermostat to shut off. However, if the freezer is broken, then dry ice will save all your frozen foods until your freezer is repaired or replaced.  If your freezer is working then it is blowing air that is very hot, relative to the temperature of the Dry ice and that hot air (24-30F) will cause the Dry ice to sublimate into gas much faster than if the freezer was just off.
 
Dry ice gives more than twice the cooling energy per pound of weight and three times the cooling energy per volume than regular water ice with no messy afterproduct.  Because it has no afterproduct, it is the preferred blasting solution for cleaning delicate machinery.
 
 
HANDLING and SAFETY
 
Prolonged contact with the skin will freeze skin cells and cause an injury that looks and feels very similar to that of a burn. Always handle dry ice with care and wear leather or insulated gloves whenever touching it.

Dry Ice and CO2 are perfectly safe if you follow a few basic safety precautions, much like fire, electricity, and knives.  All of these things add tremendous comfort and convenience to our lives, but must be treated with respect. Most plants on the planet breathe CO2 and create oxygen as a waste product. Trees, lichen, algae, vegetables, every plant grows better with a concentration of CO2 that is about triple what we currently have on planet earth.  Some of our customers pipe CO2 into their greenhouses so that their plants get a superpowered growth formulae.   As of 2024 the planet is dangerously low on CO2 in our atmosphere, currently around 430 ppm (parts per million) or about 0.04%.   If the trend over the recent 140,000,000 year period continues to go downwards all plant life on earth would die under 200 ppm!  Fortunately we've seen an upward tick in atmospheric CO2 over the last 165 year (since about 1860).  This upward tick is fantastic for plant life on the planet, and makes no significant difference to temperature.  It was once thought that CO2 was a greenhouse gas, but further investigation shows that the "greenhouse" effect of each molecule diminishes as the concentration increases.  Which means that it's already done all the warming it's going to do and we can't have any less without killing off all the tomatoes.   Check out the science behind CO2 at the CO2Coalition if you want to learn more.
 
STORAGE
 
A dry ice storage box specifically made for the storage of dry ice is the perfect container. The thicker the insulation, the slower it will sublimate. Never store dry ice in a completely airtight container because the sublimation from dry ice to a gas causes expansion and the possibility for an airtight container to explode.  If you are storing it in a cooler meant for wet ice, do yourself a favor and do not latch or clasp the lid shut, just let the lid sit in the closed position, this will allow the extra gas that's created to seep out of the container rather than build up pressure.

As dry ice sublimates into CO2 gas it pushes the oxygen in the room up into higher layers since CO2 is heavier than regular air.  You should avoid placing dry ice in an enclosed space (such as a walk-cooler) unless you take steps to monitor and ensure that the concentration of CO2 does not reach dangerous proportions for human breathing.  If you should find yourself unexpectdly somehow trapped with a bunch of sublimating dry ice, try to get to as high of an elevation as you can within the space for maximum access to oxygen.  If you can contact emergency responders, definitely let them know about the dry ice so that they understand time is of the essence and that you might need oxygen when they can free you. 

Keep proper air ventilation wherever dry ice is stored. Do not store dry ice in unventilated rooms, autos or boat holds as the carbon dioxide gas is heavier than air and sinks down to replace oxygenated air which could cause suffocation if it is breathed exclusively.
 
Even if transporting dry ice in the trunk of your car, keep your windows rolled down slightly to allow oxygenated air into the vehicle.
 
VENTILATION
 
Normal air is 78% Nitrogen, 21% Oxygen and only 0.04% Carbon Dioxide. If the concentration of carbon dioxide in the air rises above 0.5% for over 8 hours that is considered unhealthy.  If the concentration of CO2 in an enclosed area rises above 40,000 ppm or 4% then the breathable air can become immediately dangerous.
 
Smaller concentrations can cause quick breathing and headaches but is otherwise not harmful. If dry ice has been in a closed room or walk-in for more than 10 minutes, then open the doors and allow adequate ventilation before entering.
 
If you have breathed in too much carbon dioxide and not enough oxygen, then you may start to pant and breath quickly as if running a race, develop a headache or fingernails or lips may start to turn blue. Immediately leave the area; open a door; open a window; basically, increase ventilation of oxygenated air.
 
Remember that carbon dioxide gas replaces oxygenated air and can be dangerous.

If you will be in an enclosed area with Dry ice or CO2 from any source you can purchase a wearable, personal CO2 monitor that will alert you if the concentration becomes dangerous.  Just ask us about a personal CO2 monitor and we'll be happy to sell you one and explain how to use it, how to calibrate it, and how to interpret the readings.