1. What is dry ice?
Dry Ice is the solid form of Carbon Dioxide (CO2). CO2 is a colorless, tasteless, odorless gas found naturally in our atmosphere. It is what humans and animals exhale and is vital for plants grow.
2. What is dry ice blasting?
Dry ice blasting is similar to sand blasting, bead blasting, or soda blasting where Rice sized dry ice pellets are accelerated in a pressurized high velocity air stream to impact and clean a surface. It is non-abrasive to surfaces harder than the soft dry ice pellets.
3. How is dry ice stored?
Dry Ice is stored in an insulated tote with thick insulation to slow down the sublimation. Depending on the climate and thickness of the container, typical dry ice sublimation is approximately 2% to 10% per day.
4. Why would I use dry ice instead of a traditional blast media?
Most other blast media leave secondary waste behind. Dry ice sublimates (vaporizes) upon impact with the surface. All that remains is the contaminate you are removing. Also, since dry ice vaporizes on impact, the process can be used to clean complicated cavities where typical grit blast media will become trapped.
5. How does the extreme cold help clean?
Unlike other blast media, dry ice has a temperature of -109°F (-78.3°C). Because of the temperature difference between the dry ice particles and the surface being treated, thermal shock occurs during the process of dry ice blasting. This causes a breakdown of the bond between two dissimilar materials. Gummy substances and adhesives are embrittled making them easier to remove.
6. What happens to the contaminate?
Contaminates can be dry, wet, hard or soft. Dry contaminates will break up into small chips and can be swept up or vacuumed. If the particles are large enough, they do not become airborne. If the contaminate is wet, such as grease or oils, the stream will move or push the liquid away much like a high pressure water stream would, except that the surface where the contaminate was will be dry and clean. To prevent re-deposition, the operator should work in a methodical way, from the top down.
7. Do the contaminates or dry ice pellets ricochet?
Upon impact, dry ice pellets sublimate to a gaseous state and therefore dry ice particles typically do not ricochet. The removed contaminant is usually washed away by the blast jet stream and does not come directly back into the blast gun vicinity; however, safety glasses must be worn at all times during the operation of the machine.
8. Will dry ice blasting damage the substrate?
The dry ice blasting process will not damage the substrate. The size of the dry ice pellets and their velocity can be optimized to remove the contaminate while being non-abrasive to the substrate. The process can clean delicate chrome or nickel plated tools, soft aluminum or brass alloys, wire insulation, and even circuit boards without causing damage.
9. Can you use dry ice blasting to clean hot tools in place?
Yes. In fact, dry ice blasting cleans faster when the substrate is hot.
10. Does dry ice blasting cool the substrate?
Yes, but not dramatically. The amount of cooling depends on the substrate material, the dwell time of the dry ice blast stream, and the dry ice usage. For example, a 30 inch (76.2 cm) by 30 inch (76.2 cm) rubber mold may have an initial temperature of 325°F (162.8°C). After the tool has been blasted clean (approximately 12 minutes), the temperature of the mold is about 300°F (148.9°C).
11. Will the temperature drop damage the hot mold?
Generally, no. The temperature change of the surface being cleaned is small and the corresponding tensile stress will be well below the point of what most molds will encounter during normal heat treatment.
12. Will the process create condensation?
Condensation occurs when the temperature of the substrate falls below the dew point. The dew point varies with climate and the daily weather patterns. When cleaning hot substrates, condensation will rarely occur because the temperature of the surface will stay above the dew point. If condensation does form, you can control it by using heaters, heat lamps, or blow off devices.
13. How much compressed air does Dry Ice Blasting use?
A typical ice blasting system operates at 90 psi (6.2 bar) with 150 scfm (4.25 m3/min), however the need depends on the application. Our technical people will determine if a diesel compressor will be needed to provide sufficient supply.
14. How portable are the dry ice blasting machines?
In a factory setting, one person can easily roll any of the machines around the plant floor without any special equipment. In a mobile set-up, you must considers trucks, and tow-behind, diesel compressors.
15. What are the primary safety issues when dry ice blasting?
There are the same safety issues that are pertinent to using compressed air and to ensure nothing is going to get blown at someone. Another concern is the temperature of the dry ice. At -109°F (-78.3°C), we recommend wearing gloves when coming in contact with the dry ice. Eye and ear protection must be worn at all times.
16. Can Dry Ice Blasting be used to remove paint?
Yes, However the removal rate is dependent on great number of factors including: the underlying surface profile of the substrate, the thickness of the coating, the adhesive bond strength of the coating, and the cohesive strength of the coating (generally a function of age).
17. Can Dry Ice Blasting remove rust?
Dry ice blasting will remove any loosely adhered oxidation and salts, but it will not remove the deeply adhered oxidation. You will not get a white metal finish. To achieve this you have to remove the surface metal, something that dry ice blasting cannot do. In many applications however, this is a major advantage as it preserves the original profile and surface integrity of the substrate.
18. Can Dry Ice Blasting be used on a wooden surface?
Short answer: Yes. Blasting wood with dry ice may raise the grain of soft woods, leaving a finish that upon close visual inspection can reveal imperfections that for some may be not be acceptable. Hardwoods generally respond much better to DIB. There are however, specialized DIB machines that are capable of cleaning VERY gently. Ask us about them.
19. Does Dry Ice Blasting generate static electricity?
It does. All dry air processes will generate a degree of static electricity and dry ice blasting is no exception. Dry Ice Blasting equipment is designed with integral grounding devices. As long as both the blasting unit and the workpiece are properly grounded to a good earthing point, you are very unlikely to have static discharge problems.