Dry Ice FAQ

If there is a question you have and the answer cannot be found on our website, please contact us at info@coldjet.com.au or 1300 COLD JET (+61 2 9600 9570).

 

Q: What is dry ice?

A: Dry ice is the solid form of Carbon Dioxide (CO2). CO2 is a colourless, tasteless, odourless 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 pressurised 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, and the better it is sealed, the slower it will sublimate. the rate of sublimation depends on the suitability of the container. Cold Jets world leading containers can restrict sublimation to just 4-5% per day. By comparison; in a normal polystyrene box sublimation would be closer to 30% per day.

 

Q: Why would I use dry ice instead of a traditional blast media? 

A: Most other blast media leave secondary waste and residue behind. Dry ice sublimates (vaporises) upon impact with the surface. All that remains is the contaminant you are removing. Also, because dry ice vaporises on impact, the process can be used to clean complicated cavities where typical grit blast media will become trapped. Dry ice blasting is also regarded as non-abrasive and will not damage tooling as opposed to other blast media.

 

Q: How does the process work? 

A: Unlike other blast media, dry ice has a temperature of -78.3°C (-109°F). Because of the temperature difference between the dry ice particles and the surface being treated, an extremely brief thermal shock occurs during the process of dry ice blasting. This causes a breakdown of the bond between two dissimilar materials. The thermal shock is instantaneous, and has been tested and accepted by the worlds leading engineering companies to not cause problems with substrates associated to this thermal shock

 

Q: What happens to the contaminant? 

A: Contaminants 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 contaminant is wet, such as grease or oils, the Cold Jet® stream will move or push the liquid away much like a high pressure water stream would, except that the surface where the contaminant was will be dry and clean. To prevent redeposition, the operator should work in a methodical way, ie. 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 Cold Jet® dry ice blasting process will not damage the substrate. The size of the dry ice pellets and their velocity can be optimised to remove the contaminant while being non-abrasive to the substrate. The Cold Jet® 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 Cold Jet® 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 significantly. 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 75cm by 75cm rubber mould may have an initial temperature of 165°C. After the tool has been cleaned (approximately 12 minutes), the temperature of the mould will be about 145°C.

 

Q: Will the temperature drop damage the hot mould? 

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 moulds 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 DVD to reference and train staff. The only other items needed to operate your Cold Jet Dry Ice blast system are plant air, electric power (standard 240V), and dry ice pellets or block (depending on the system).

 

Q: How much air will I need? 

A: A typical Cold Jet dry ice blast system operates at 80 psi (5.5 bar) with 150 scfm (4.25 m3/min), however your needs will depend on your application. Low flow nozzles are available, which require only 50 scfm (1.42 m3/min) at 80 psi (5.5 bar).

 

Q: Where can I find dry ice pellets, nuggets and/or block? 

A: In Australia call 1300 COLD JET (+61 2 9600 9570). We supply dry ice in every state of Australia.

 

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 organisations have given Cold Jet® their stamp of approval for the use of dry ice in outdoor blasting applications, including the California Environmental Protection Agency.

 

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 Cold Jet dry ice blast equipment is approximately 0.7 kg per minute.

 

Q: Will I need an after-cooler? 

A: Dry air is important for the reliable operation of your blast unit. An after-cooler is recommended whenever your air source is a diesel portable compressor. An aftercooler should remove 70% of the water in your compressed air which will be sufficient to proetect the blast unit. But weather and humiditiy will determine whether an aftercooler is sufficient to eliminate moisture making its way all the way through the blast system and onto the item being cleaned.

If a totally dry surface is required then further air treatment may be necessary, or the use of heaters.

Your sales representative will be able to assess your needs and recommend the proper system configuration to ensure your productivity is maximised with moisture-free delivery of dry ice from your Cold Jet dry ice blast system.

 

Q: How much maintenance is required to maintain my system? 

A: With Cold Jet - Very little. Cold Jet's patent protected 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.

Cold Jet's equipment is patent protected, the patent protected feeder is a not a scheduled replacement item. This is a major difference between Cold Jet equipment and other brands. Other brands require you to replace/rebuild their feeder system every 300 hours of operation (costing thousands of dollars). Thus the competitor systems are slowly wearing out from the moment it starts operation, this means performance is slowly deteriorating with every revolution, and problems increase with each passing hour until that rebuild occurs.

Blast hoses are another item that competitor equipment requires you to replace every 12-24 months. Costing multiple thousand dollars per length of hose. Cold Jet equipment will save you thousands of dollars in maintenance costs every year. 

 

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. When operating in a confined space forced ventalitaion becomes imperative, and we always recommend the use of a gas monitor to monitor CO2 and Oxygen levels.

 

Q: What are the primary safety issues when dry ice blasting? 

A: One safety issue is to protect workers from moving parts. Cold Jet 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°C (-109°F), 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 turbulence which 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 is sucked via venturi effect up one hose, while the compressed air travels 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. Therefore Single-hose systems have the ability to generate a much higher dry ice pellet velocity, and therefore will be the better choice when needing a more aggressive clean. Dual hose systems have been all-but superceded in the marketplace.

 

Q: How do I know if I want pellets or shaved block particle blasting systems? 

A: The shaved dry ice particles have an advantage when removing most paints or when cleaning equipment with intricate geometries or tiny openings such as microvents or 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 disbond it.

 

Q: Is there a difference between types of dry ice pellets and dry ice suppliers?

A: Absolutely. Since dry ice is a naturally soft media, Cold Jet has spent millions of dollars developing dry ice production equipment to manufacture the highest density dry ice. Cold Jet manufactured dry ice is EXTRUDED under thousands of pounds of pressure to remove any CO2 gas inclusions which will accelerate the sublimation of the dry ice. This can be seen through the length and clarity of a Cold Jet dry ice pellet, as opposed to the shorter crumbly fragments that non-Cold Jet equipment pushes out.

Non-Cold Jet dry ice will disappear quicker, not have the density of the pellet, and thus a slower cleaning time, and the smaller pellets also attract more moisture from the atmosphere that will clog up a dry ice cleaning machine causing reliability issues.

Cold Jet Australia also invest in the highest quality dry ice storage boxes. A poor box with a poor seal will dramatically reduce the useable life of your dry ice. Particularly with the smaller 3mm dry ice pellets.

Why pay for inferior quality? Insist on Cold Jet dry ice today!