Dry Ice Blasting with Cold Jet
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F A Q

FREQUENTLY-ASKED QUESTIONS ABOUT DRY ICE BLASTING

Click on any question to jump to that section. Para Preguntas Frecuentas pulsar aquí.

What is dry ice?
What is dry ice blasting?
How do I store dry ice?
Why would I use dry ice instead of a traditional blast media?
How does the process work?
What happens to the contaminate?
Do the contaminates or dry ice pellets ricochet?
Will dry ice blasting damage the substrate?
Can you use Cold Jet dry ice blasting systems to clean hot tools online?
Does dry ice blasting cool the substrate?
Will dry ice blasting cause thermal stress to my tools?
Will the process create condensation?
What equipment will I need?
How much air will I need?
Where can I find dry ice pellets?
Does using pellets have an advantage over using block dry ice?
Are there differences in effectiveness of dry ice pellets vs. block dry ice granules?
What is the difference between a single-hose system and a dual-hose system?
How big is a Cold Jet dry ice blasting machine?
Is it safe to use dry ice blasting outside?
What influence does pellet size, air pressure, and pounds per minute have on system efficiency?
Which is more efficient, pellets or nuggets?

What is dry ice?
Dry Ice is the solid form of Carbon Dioxide. Dry Ice is a colorless, tasteless, odorless gas found naturally in our atmosphere.
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What is dry ice blasting?
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 the surface to be cleaned.

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How do I store dry ice?
Dry ice pellets are delivered to your plant in sealed insulated containers. Depending on the climate, the pellets will last in their container for 5 to 12 days. Once the seal is broken, the ice should be used in 1 to 3 days.

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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.

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How does the process work?
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.

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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 Cold Jet® 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 redeposition, the operator should work in a methodical way, from the top down.

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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.

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Will dry ice blasting damage the substrate?
The Cold Jet® 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 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.

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Can you use Cold Jet® dry ice blasting to clean hot tools online?
Yes. In fact, dry ice blasting cleans faster when the substrate is hot.

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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).

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Will dry ice blasting cause thermal stress to my tools?
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.

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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 warm air knives.

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What equipment will I need?
The system will come complete from Cold Jet. The only other items you will need are plant air, electricity, and dry ice pellets.

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How much air will I need?
ColdJet's single-hose Radial Feed Series and dual-hose Venturi system typically operate at 80 psi (5.5 bar) with 150 scfm (4.25 m3/min), but low flow nozzles are available, which require only 100 scfm (2.83 m3/min) at 80 psi (5.5 bar).

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Where can I find dry ice pellets?
Dry ice pellets are available all over the world. In the United States, call +1-800-SEND-ICE (+1-800-736-3423) or +1-513-831-3211 for a location near you.

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Does using pellets have an advantage over using block dry ice?
Yes! Using only 1.5 to 2.5 pounds (0.68 to 1.14 kg) of pellets per minute, Cold Jet's single-hose pellet blasting systems can clean two to five times faster than a two-hose block dry ice shaver system. The single-hose system has superior cleaning capability and can significantly reduce production downtime and correspondingly yield thousands of dollars in production savings beyond what is attainable with a two-hose block dry ice system. Below is a comparison study of Cold Jet's single-hose dry ice pellet based system versus a competitor's two-hose shaved dry ice block system. The test was done on both sides of a single two-tire press. Both tests were done by the same operator.

  ColdJet's Single-Hose Pellet Blasting System Two-hose Dry Ice Block Shaving Blast System
Top half side wall cycle   4 min. 10 sec. 11 min. 40 sec.
Nozzle   low pressure round
Blasting Pressure   60 psi / 4.14 bar 70 psi / 4.83 bar
Pellet/block feed rate   50% 60%
Bottom half side wall cycle   4 min. 25 sec. 11 min. 0 sec.
Nozzle   low pressure round
Blasting Pressure   60 psi / 4.14 bar 85 psi / 5.86 bar
Pellet/block feed rate   50% 60%
Total cleaning cycle   8 min. 35 sec. 22 min. 40 sec.
Total dry ice usage   27.6 lbs / 12.5 kg 44 lbs / 20 kg

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Are there differences in the effectiveness of dry ice pellets vs. block dry ice granules?
Yes! The differences are significant when it comes to adapting the pellet size and aggression level to the needs of a particular application. Shaving dry ice blocks produces only a snow-like blast granule that is limited to thin layer contaminate removal. A Cold Jet® single-hose dry ice blasting system mechanically feeds a 3mm diameter pellet into the blast hose. The particular hose and blasting nozzle being used govern the actual pellet size impacting the surface.
For a more technical explanation of the difference in effectiveness between pellets and block shaved dry ice, click here.
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What is the difference between a single-hose system and a dual-hose system?
In a dual-hose Venturi Series dry ice blasting system, an ejector type nozzle, similar to a conventional abrasive media blasting nozzle, is used to combine the compressed air stream with the dry ice particle carrying vacuum stream created by the ejector. In Cold Jet's single-hose Radial Feed Series dry ice blasting systems, the dry ice pellets are mechanically fed into the air stream. No energy is wasted creating a vacuum to pull the pellets through a separate line. A significant drawback of a two dual-hose system is the limitation on blast hose length. Because the dual-hose ejector nozzle relies on a vacuum to pull the pellets into the air stream, the hose length cannot go much beyond 25 feet (7.62 meters) before pressure losses through the pellet hose overcome the maximum vacuum capability of an ejector nozzle. For a more technical explanation of the difference between a single-hose dry ice blasting system and a dual-hose dry ice blasting system, click here.

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How big is a Cold Jet® dry ice blasting machine?
  • The Cold Jet® VSH is 34 inches / 86 cm (L) by 20 inches / 51 cm (W) by 38 inches / 96.5 cm (H)
  • The Cold Jet AeRO 75 is 34 inches / 86 cm (L) by 20 inches / 51 cm (W) by 40 inches / 101.5 cm (H).
  • The Cold Jet AeRO 30 is 25 inches / 63.5 cm (L) by 17 inches / 43.2 cm (W) by 30 inches / 76.2 cm (H).

All three units are easily moved from one area to another.
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Is it safe to use dry ice blasting outside?
Yes. CO2 dry ice pellets are safe to use in outdoor blasting applications. In fact, many organizations have given Cold Jet® their stamp of approval for the use of pellets in outdoor blasting applications, including the California Environmental Protection Agency.

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What influence does dry ice pellet size, air pressure, and pounds per minute have on system efficiency?
Dry ice pellet size is usually optimum at 3 mm, the size that is available commercially for pick up or delivery. When a smaller pellet (particle size is desired) it is usually accomplished by using a 3/4" (1.9 cm) blast hose (1" (2.54 cm) is standard), a blast hose with a ribbed interior or a nozzle that accomplishes this, or a combination of these 3 parameters. This is often done to work on a thin coating or to protect a sensitive surface.

Air pressure has a direct effect on the velocity of the dry ice particles and the velocity of the particles has a direct effect on the energy being imparted to the surface, which can mean both higher removal rates and also a greater potential for surface damage.

Pounds/kg per minute of dry ice delivery can be optimized. There is an optimum setting that is related especially to the particular nozzle (and other parameters being used) and also highly related to the application. A higher setting beyond the optimum does not translate into a higher removal rate. In most cases a higher than optimum setting of dry ice delivery will cause the particles to decrease in velocity and therefore decrease the removal rate, and, of course, will cost more. Many nozzles and applications are optimized between 2-3 pounds (1 to 1.5 kg) per minute.
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Which is more efficient, pellets or nuggets?
We use the term pellets to mean dry ice formed in 3mm-diameter extrusions or less. The 3 mm size is available commercially for pick up or delivery, and while smaller sizes do have value for selected applications they do not transport well enough and are not in high enough demand be sold commercially. Sizes larger than 3 mm in diameter are generally referred to as nuggets and they are too large for blasting as they do not develop as much velocity and they induce surface damage more readily.

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