Frequently asked questions regarding Dry Ice, Dry Ice Production and Dry Ice Blasting. If there is a question you have and the answer cannot be found on our website, please feel free to contact us at co2clean@freezeco2.comor (86) 0592-6220885.
Q: What is dry ice?
A: Dry Ice is the solid form of Carbon Dioxide (CO2). CO2 is a colorless, tasteless, odorless gas found naturally in our atmosphere.
Q: What is dry ice blasting?
A: Dry ice blasting is similar to sand blasting, bead blasting, or soda blasting where a media is accelerated in a pressurized air stream (or other inert gas) to impact and clean a surface.
Q: How do I store dry ice?
A: Dry Ice should be stored in an insulated container. The thicker the insulation, the slower it will sublimate. Depending on the climate and thickness of your container, typical dry ice sublimation is approximately 2% to 10% per day.
Q: Why would I use dry ice instead of a traditional blast media?
A: Most other blast media leave secondary waste behind. Dry ice sublimates (vaporizes) upon impact with the surface. All that remains is the contaminants 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.
Q: How does the process work?
A: Unlike other blast media, dry ice has a temperature of -78.3¡ãC. 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.
Q: What happens to the contaminants?
A: 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 FREEZECO2JET 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 redeposit, the operator should work in a methodical way, from the top down.
Q: Do the contaminants or dry ice pellets ricochet?
A: 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.
Q: Will dry ice blasting damage the substrate?
A: The FREEZECO2JET 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 contaminants while being non-abrasive to the substrate. The FREEZECO2JET process can clean delicate chrome or nickel plated tools, soft aluminum or brass alloys, wire insulation, and even circuit boards without causing damage.
Q: Can you use FREEZECO2JET dry ice blasting to clean hot tools online?
A: Yes. In fact, dry ice blasting cleans faster when the substrate is hot.
Q: Does dry ice blasting cool the substrate?
A: 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 76.2 cm by 76.2 cm rubber mold may have an initial temperature of 162.8¡ãC. After the tool has been blasted clean (approximately 12 minutes), the temperature of the mold is about 148.9¡ãC.
Q: Will the temperature drop damage the hot mold?
A: 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.
Q: Will the process create condensation?
A: 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.
Q: What equipment will I need for my cleaning application?
A: The dry ice blast system will come complete with blast and air hose, applicator and nozzle best suited for your application and a training CD to reference and train staff. The only other items needed to operate your FREEZECO2JET Dry Ice blast system are plant air, electric power from a common wall receptacle, and dry ice pellets or block (depending on the system).
Q: How much air will I need?
A: A typical FREEZECO2JET dry ice blast system operates at 5.5 bar with 4.25 m3/min, however your needs will depend on your application. Low flow nozzles are available, which require only 1.42 m3/min at 5.5 bar.
Q: How portable are the dry ice blasting machines?
A: One person can easily roll any of the machines around the plant floor without any special equipment.
Q: Is it safe to use dry ice blasting outside?
A: Yes. CO2 dry ice is safe to use in outdoor blasting applications. In fact, many organizations have given FREEZECO2JET their stamp of approval for the use of dry ice in outdoor blasting applications.
Q: How much dry ice should I expect to use?
A: The amount of dry ice needed to clean effectively can vary dramatically with each dry ice blast system and cleaning application. The average ice consumption for FREEZECO2JET dry ice blast equipment is approximately 1.1 kg per minute.
Q: Will I need an after-cooler?
A: After-cooler may be useful if you are a contract cleaner or restoration contractor using a portable diesel compressor as your air source. An after-cooler provides assurance that the FREEZECO2JET dry ice blaster will not blast any moisture from the diesel compressor being used. This is primarily dependant on humidity levels.
Your sales representative will be able to assess your needs and recommend the proper system configuration to ensure your productivity is maximized with moisture-free delivery of dry ice from your FREEZECO2JET dry ice blast system.
Q: How much maintenance is required to maintain my system?
A: Very little. FREEZECO2JET dry ice blast systems are designed to provide years of trouble-free use with a minimum amount of maintenance. Each system comes with an operator manual that outlines recommended routine maintenance - periodically checking filters and examining hoses for cracks are two examples.
Q: Is it okay to blast in an enclosed area?
A: Yes, with proper ventilation. Because CO2 is 40% heavier than air, placement of exhaust vents at or near ground level is recommended when blasting in an enclosed area. In an open environment, existing ventilation is sufficient to prevent undue CO2 buildup. Even though CO2 is non-poisonous, it does displace oxygen in the atmosphere.
Q: What are the primary safety issues when dry ice blasting?
A: One safety issue is to protect workers from moving parts. FREEZECO2JET equipment is designed so that workers do not have access to moving parts without shutting down the system.
Another concern is the temperature of the dry ice. At -78.3¡ãC, we recommend wearing gloves when coming in contact with the dry ice. Eye and ear protection should be worn at all times.
Q: How loud is the system?
A: Noise is a function of air volume and air velocity. Within the nozzle, the stationary air is sheared by the high velocity air causing turbulencewhich creates noise. With appropriate hearing protection an operator can safely operate the system all day.
Q: What is the difference between a single-hose system and a dual-hose system?
A: With a dual-hose blast system, the dry ice travels in one hose and the high-pressure air in another. They are not mixed until just before they exit the nozzle.
Single-hose blast systems mix the high-pressure air and the dry ice from the time it leaves the machine. Single-hose systems can at times be the better choice when needing a more aggressive clean.
Q: How do I know if I want pellets or shaved block particle blasting systems?
A: The smaller shaved particles have an advantage when removing most paints or when cleaning equipment with intricate geometries or tiny openings such as screens. Pellets are more suitable when removing thick contaminants - as the larger mass behind each individual pellet is better able to penetrate the contaminant and create the shockwave necessary to peel off it.
As the pellets of dry ice impact onto the surface to be treated, a thermal differential is established between the substrate and the contaminants. Meanwhile the pellets sublimate and these gaseous molecules of CO2 enter through the pore spaces between the contaminants and the substrate. Since the volume expand 800 times instantaneously, thus pushing the contaminants from underneath, further assisting in the removal process.