Dry Ice Blasting
What is Dry Ice Blasting?
Dry ice blasting is similar to sand blasting, plastic bead blasting, or soda blasting where a medium is accelerated in a pressurized air stream to impact a surface to be cleaned or prepared. But that's where the similarity ends.
Instead of using hard abrasive media to grind on a surface (and damage it), dry ice blasting uses soft dry ice, accelerated at supersonic speeds, and creates mini-explosions on the surface to lift the undesirable item off the underlying substrate.
Process of Dry Ice Blasting
Dry Ice Blast Cleaning works like every particle blasting process - sand - soda - bead - or steam blasting. The frigid temperature of the dry ice -109.3°F or -78.5°C "blasting" against the material to be removed, can cause it to shrink and loose adhesion from its sub surface. Additionally when some of of dry ice penetrates through the material to be removed, it comes in contact with the underlying surface. The warmer sub surface causes the dry ice to convert back into carbon dioxide gas. The gas has 800 times greater volume and expands behind the material speeding up its removal. Paint, oil, grease, asphalt, tar, decals, soot, dirt, ink, resins, and adhesives are some of the materials removed by this procedure. Only the removed material must be disposed of, as the dry ice sublimes into the atmosphere.
Replacing Sandblasting:
In many cases this method is superior to sandblasting because the dry ice is soft enough not to pit or damage the underlying surface. The dry ice sublimes quickly into the air and only the removed material must be cleaned up. Dry Ice blasting eliminates equipment damage in two ways. First, dry ice does not erode or wear away the targeted surface as traditional grit media and even wire brushes do. This means that surface integrity and critical tolerances are preserved and equipment will not have to be replaced due to surface erosion common with sand, glass beads, and other abrasive media. Second, with traditional cleaning methods, equipment is often damaged (bumped, dropped, etc.) while in transit to or from the dedicated cleaning area. Instead most equipment and machinery can be cleaned while in place.
Replacing Steam or Water Blasting:
Sometimes Dry Ice Blasting is also an improvement over steam and water blasting for several reasons:
1) Electrical parts and generators can be immediately put back into service used without waiting to dry.
2) Radioactive contaminate removal doesn't require large storage containers for contaminated water.
3) Mildew and mold removal are far more complete with less chance of regeneration because of water vapor or moisture.
4) Dry ice blasting removes more algae, sea slime, and mussels on boat hulls, than water blasting, which allows the organic matter to reattach sooner.
Replacing Environmentally Damaging Solvents:
Many times Dry Ice Blast Cleaning is used in place of many environmentally damaging solvents. These chemicals include trichlorethane, methylene chloride, perchlorethane, orthodichlorobenzene, cresylic acid, and caustic solutions. Since dry ice evaporates completely as a gas it leaves no wastes. Only the material being removed must be disposed of. When dry ice cleaning replaces hazardous chemical cleaners the disposal cost of that chemical is eliminated. Tinker Air Force Base has reported it eliminated hazardous waste disposal associated with 17,000 gallons of chemicals they no longer need to use each year because of dry ice cleaning.
Applications of Dry Ice Blasting
Adhesives
Adhesives are easily removed in comparison to alternative methods as the lowered temperature serves to weaken the adhesive bond. Many companies are blast cleaning old labels off containers that are being re-used. Abrasive methods often generate heat therefore failing with some adhesive removal. Simple glue over-runs left on a conveyor belt can be dry ice blast cleaned while the conveyor belt is running.