What is Dry Ice Blasting - CO2 Blasting ?
It is a process in which Dry Ice particles are propelled at a high velocity to impact and clean a surface. As with other blasting systems, the particles (dry ice) are propelled with compressed air. Many applications can use standard shop air, however the rate (amount of CFM's, PSI) will vary depending on the equipment used and the nature of the items (substrate) wanted to be removed.
How does it remove contaminants ?
By a thermal shock, the dry ice causes the bond between the coating and substrate to shift. If you are trying to remove a viscous coating - the cleaning process is vary similar to high pressure water. If you are trying to remove a brittle contaminant (i.e. paint) - the process literally pops the coating off from the inside out.
What happens to the DRY ICE once it strikes the surface ?
It sublimates, returns to the atmosphere in its natural form as a gas. CO2 is a naturally occurring versatile chemical in nature and in industry.
Does the DRY ICE cool the substrate - object being cleaned ?
Yes, it cools the object temporary, however its is not as much as you might think. The amount of cooling depends on 3 factors: Mass of the target surface, the amount of ice usage and the dwell Time.
Will the Process create condensation ?
The three factors come into effect again: mass of surface, ice usage and dwell time. There will be condensation if you cool the substrate below the dew point. Dewpoints will vary depending on your local climate. Job sites in the deep south with a higher dewpoint will experience more condensation than a job site in the southwest desert areas.
Is the system noisy ?
YES. Noise is a function of air volume and air velocity, Hearing protection is required for both operators and observers of this cleaning methods.
How much DRY ICE should I expect to use in an Hour ?
Depends on the application (surface, the contaminates, and the quantity to be removed) Most of the equipment on the market today, use an average of 1-2 pounds per minute while the trigger is engaged. When cleaning, the trigger is not engaged constantly, average hourly rate is between 60-100 pounds of dry ice.
How do you store DRY ICE ?
Since dry ice is a -109°F putting it in a freezer doesn't help. For storage and transportation, special insulated containers are used. Depending on the quality of the storage container, current dewpoints, and how much ice you are storing, your loss due to sublimation can range from 2% to 15% per day. Examples of the storage containers can be located under the equipment section
What are some examples of applications where Dry Ice Blasting does not work well ?
Blasting technique is the line-of sight cleaning method. If you can't see what you are trying to clean, you probably can't clean it with dry ice. The contamination to be removed must accessible by the blast stream, since dry ice has limited effects around closed corners. The substrate should also be able to withstand the physical effects of the blast air and the dry ice impingement. Small tubes or channels are difficult to clean. Small, fragile items are possible only with extreme car.