Dry ice blasting is an innovative and environmentally friendly cleaning technology that uses solid carbon dioxide (CO2) particles, commonly known as dry ice, as a cleaning agent. These particles are propelled at high speed onto the surfaces to be cleaned thanks to a pneumatic spraying system. Upon impact, the dry ice undergoes instantaneous sublimation, passing directly from a solid to a gaseous state without passing through a liquid state. This phenomenon creates a thermal shock on the contaminated surface, which allows the dirt particles or layers to be detached without damaging the substrate.

This process is extremely effective in removing various types of contaminants, such as greases, oils, waxes, production residues, and even some coatings without requiring the use of chemical solvents, water, or abrasive methods. It is therefore particularly suitable for cleaning sensitive parts or in environments where the use of water is prohibited or undesirable.

The speed at which the dry ice pellets are propelled depends largely on the system used, as well as several adjustable parameters such as pressure, air volume, and nozzle type. In general, dry ice blasting systems can be classified into two main categories based on their design and projection speed:

• Twin-tube or venturi system: These systems allow for projection speeds of between 60 and 120 meters per second (m/s). They are often used for general cleaning applications where effective dirt removal is required without specific spray speed requirements. See
  twin-tube cryogenic machine
  
• Single-hose system with supersonic nozzle: These systems are capable of propelling dry ice pellets at speeds exceeding 290 m/s, offering increased cleaning capacity for more demanding tasks or for surfaces that are particularly difficult to clean. See single-hose dry ice blasting machine

In addition to its advantages in terms of efficiency and environmental friendliness, dry ice blasting is also valued for its ability to significantly reduce the downtime of industrial equipment, as it can often be performed without dismantling the machines or equipment. This method also helps to extend the life of assets by avoiding premature wear and tear from more abrasive cleaning methods.

The origin of cleaning by dry ice blasting process, also known as “dry ice blasting,” dates back to the 1950s. However, it was not developed and commercialized as an industrial cleaning technique until the 1980s. This method was invented and explored as an alternative to traditional cleaning techniques, which used chemical solvents, pressurized water, or abrasive methods that could damage surfaces or be harmful to the environment.

The fundamental discovery behind dry ice blasting is the ability of dry ice to sublimate, meaning it passes directly from a solid to a gaseous state without becoming liquid upon contact with the surfaces to be cleaned. This unique property allows contaminants to be effectively removed without leaving residues, unlike traditional cleaning methods that can leave secondary waste or require additional cleaning.

The introduction of this technique revolutionized many industries by offering a non-abrasive cleaning solution, no water required and environmentally friendly . Dry ice blasting has proven particularly useful in sectors such as aerospace, automotive, food and and the beverage, plastics, foundry, and electronics, where equipment and component cleanliness is crucial and where the use of water or solvents can pose safety, quality, or environmental issues.

Since its introduction, dry ice blasting equipment and technology have evolved considerably, offering increased efficiency, better ergonomics for operators, and greater adaptability to a wide range of industrial cleaning applications.

Dry ice blasting works in three main stages, based on the use of dry ice in the form of pellets or particles:

1. Projection : The dry ice pellets are placed inside a dry ice blasting machine, then accelerated high speed using a jet of compressed air through a specially designed blast nozzle. This acceleration allows the particles to strike the surface to be cleaned with high kinetic energy (Ke=1/2 mv²)
2. Thermal shock : The impact of the dry ice pellets on the surface creates a thermal shock that weakens the bond between the dirt and the surface. The temperature difference between the dry ice (approximately -78.5°C) and the surface leads to a rapid thermal contraction of the dirt layer, making it easier to remove.
3. Sublimation : At the moment of impact, the dry ice passes directly from a solid to a gaseous state (sublimation), considerably increasing its volume by a ratio of 1:400 or 1:700 (depending on the ambient temperature). This change of state causes a rapid expansion that helps to "blow" the dirt off the surface without abrasion or damage, while leaving the surface clean and dry, without water or solvent residues.

This process allows for efficient cleaning without the use of chemicals, without generating secondary waste and without damaging surfaces, making it an environmentally friendly and safe cleaning method for many industrial applications.

Dry ice blasting and sandblasting are two industrial cleaning methods, but they differ in their principles, media used, and impacts on the treated surfaces:

Cleaning Media:

• Dry ice blasting: Uses solid dry ice pellets that sublimate upon contact with surfaces.
• Sandblasting: Employs solid abrasive particles such as corundum, glass, grit...

Mechanism of action:

• Sanding: Works by abrasive mechanical action, where solid particles hit the surface and physically erode or remove dirt, paint, rust, etc.
• Dry ice blasting: Works through thermal shock and sublimation, where the cold contact of the dry ice pellets with the surface creates a thermal shock that weakens contaminants before sublimation expels them from the surface.

Surface effects:

• Dry ice blasting: Non-abrasive, does not deteriorate the treated surface and leaves no secondary residue, as the sublimated dry ice disperses into the atmosphere.
• Sandblasting: Potentially abrasive, can alter the surface texture or cause damage if improperly applied. Generates secondary waste (worn abrasive particles and removed materials) that must be collected and disposed of.

Applications:

• Dry ice blasting: Ideal for precision cleaning, sensitive equipment, and environments where water or residues are problematic.
• Sandblasting: More suitable for removing thick coatings, rust, or for surface preparation before painting or coating, where abrasion is necessary.

Environmental and safety considerations:

• Dry ice blasting: More eco-friendly, reduces the risk of chemical contamination and minimizes operator exposure to hazardous chemicals.
• Sandblasting: Can generate harmful dust and waste, requiring strict control measures for operator safety and environmental protection.

In summary, the choice between dry ice blasting and sandblasting depends on the nature of the dirt to be removed, the type of surface to be cleaned, environmental considerations, and specific cleaning objectives. In addition, sandblasting generates a lot of dust and it is usually not possible to clean on site.

Upon impact with a surface, the dry ice undergoes sublimation, passing from a solid to a gaseous state without becoming liquid. This process releases carbon dioxide (CO2), a natural component of air, which participates in essential ecological cycles such as photosynthesis. Although CO2 is a greenhouse gas, its release in this context does not introduce chemical pollutants into the environment, integrating into natural cycles without directly contributing to global warming.

During dry ice blasting, contaminants are removed from the surface in an efficient and controlled manner. Here is a precise and concise explanation of what happens to contaminants:

• Dry contaminants : After being detached from the surface by the dry ice blasting action, these particles fall by gravity. They can be collected on a surface prepared for this purpose, such as a plastic sheet, making them easy to pick up. Disposal is then simply done using an industrial vacuum cleaner, or by direct collection for appropriate reprocessing or disposal.
• Viscous contaminants : For more adherent substances, such as grease or oils, the dry ice method also detaches them, but their collection requires specific planning. The process is carried out by guiding these contaminants from their initial location (point A) to a predefined collection point (point B), where they can then be treated or further cleaned, for example, using high-pressure cleaning or other appropriate methods to ensure complete removal.

This strategic approach to contaminant collection ensures that dry ice blasting is not limited to moving dirt from one point to another, but contributes to efficient and ecological waste management.

The Cryoblaster ATX equipment is designed for cleaning operations with dry and clean air (available in most factories).

Although the ATX series includes an internal micron filter as standard, an additional air dryer will be necessary in exceptional circumstances:

– lack of compressed air treatment at the customer's site,
– rental of a compressor without a compressed air treatment system

You should always purge the compressed air lines before connecting them to your ATX unit. This will remove any water and dirt that may be present (see methodology in your ATX User Manual).