By Guillaume Jobin on November 28, 2023
Laser Cleaning
Dry ice blasting is a non-abrasive process that uses compressed air to shoot dry ice pellets at a surface. Unlike abrasive blasting, it does not leave blasting residues behind. Instead, the dry ice turns into gas and goes into the venting system. With this method, there is no need to clean up secondary waste from abrasive materials.
It is used in various industries, including the automotive, aerospace, power generation, pharmaceutical, electrical, electronical and food industries.
While the method is praised for its advantages, it also comes with several disadvantages. In this article, we’ll go over the different aspects of dry ice blasting to better understand when it’s worth it, and which alternatives to consider.
Dry Ice Blasting Applications
Dry ice blasting is ideal to clean production line equipment or sensitive components. For example, it is used to clean painting equipment, electronic components, dies, and molds. At high velocity, the blasting media can remove contaminants like grease, surface rust, and paint from all types of substrates, whether they are made of plastic, rubber, or metal.
Dry ice blast cleaning can also prepare surfaces for painting and coating. But since it is non-abrasive, it does not generate a texture that improves adhesion, making it less efficient than other cleaning methods like sandblasting, chemical cleaning, and laser cleaning.
What is Dry Ice?
Dry ice is the solid form of carbon dioxide (CO2). It is obtained by bringing carbon dioxide at -109.3°F (-78.5°C), which is the temperature at which it freezes and turns into solid.
Disadvantages of Dry Ice Blasting
1. High Consumable Costs
Dry ice blasting comes with high consumable and operating costs, including recuring costs for dry ice pellets and compressed air. It is also an energy-hungry technology, so it is very expensive in terms of energy consumption (air compressors are among the highest recurring expenses in factories).
2. Dry Ice Shortages
Dry ice, like all consumables, needs to be stored in sufficient quantities to keep the production line running. This puts manufacturers at risk if there is a shortage or a supply line disruption, which is increasingly likely with the current global situation. In Europe, the rising cost of natural gas in 2022 has caused dry ice shortages. A similar problem happened in the US in 2022 due to a shortage of CO2.
3. Ventilation
At normal atmospheric pressure, dry ice pellets go from solid to gas when they unfreeze, producing carbon dioxide gas. This reaction is called sublimation, and it happens when pellets hit the surface during the blasting process. Dry ice can also naturally sublime in your storage units or during transport.
If carbon dioxide is allowed to build up, workers can lose consciousness or even die from asphyxia. This is particularly dangerous in small rooms. Explosions can also occur in closed containers due to pressure buildups.
Making sure you have a good ventilation system in relevant areas is essential to safety.
4. Personal Protective Equipment (PPE)
The blasting process generates intense noise levels, sometimes reaching 115 dB during cleaning. Hearing protection is highly recommended to prevent permanent damage to hearing.
Workers handling dry ice also need to wear insulated gloves, as dry ice pellets can burn the skin (frostbites). Additional PPE like safety glasses and face shields may be needed, depending on how dry ice is handled.
5. Not as Environmentally Friendly as Claimed
Dry ice blasting is often advertised as environmentally friendly. The argument is that dry ice blasting is made from reclaimed CO2 and that the cleaning process does not add CO2 to the atmosphere.
In truth, dry ice is made from the CO2 harvested when refining ammonia, ethanol, petroleum, or other chemicals—processes that are far from good for the environment.
The cleanliness of the process also depends on how dry ice users manage the CO2 gas generated during blasting. If the gas is vented into the atmosphere, then the process is not clean. If the gas is captured, frozen, and turned into new dry ice pellets to be used again, then the process is greener.
This can be done by adding a recovery unit and a pelletizer to your manufacturing process. But this equipment is expensive, and the conversion rate from liquid CO2 to dry ice is ∼40%, which means that ∼60% is released into the atmosphere. The high energy consumption of air compressors and storage tanks also adds to the ecological footprint, especially if the energy doesn’t come from a renewable source. Finally, dry ice pellet delivery trucks add an additional layer of pollution.
Dry ice blasting is certainly cleaner than alternatives like chemical cleaning, but it’s wrong to call it ecofriendly. It adds CO2 to the atmosphere and could be replaced by cleaner technologies like laser cleaning.
Dry Ice Blasting Machines: What You Need to Run One
Dry ice blasting machines operate using specific equipment and consumables to clean surfaces. Here's a breakdown of the most important components:
- Dry ice pellets: These are the primary consumables used in dry ice blasting machines. They are made from solid carbon dioxide.
- Dry ice container: Dry ice is stored in an insulated container that maintains temperature at around -78.5°C to prevent dry ice from sublimating too quickly. The container needs to be well-ventilated to avoid the buildup of carbon dioxide gas.
- Ventilation system: The area where the dry ice container is located requires proper ventilation to prevent the buildup of carbon dioxide gas. Adequate ventilation ensures safety by allowing the CO2 gas to dissipate, preventing it from reaching dangerous levels. Confined areas are not recommended to store dry ice.
- Air storage tank: The compressed air used in dry ice blasting systems is stored in specialized tanks designed to hold pressurized air. These tanks store the compressed air at high pressure. Compressed air provides the force needed to accelerate dry ice pellets and is released at high pressure to propel the pellets towards the surface to be cleaned.
- Hose system: There are two types of systems used to propel dry ice. With one-hose systems, dry ice and compressed air go through the same hose and nozzle. With two-hose systems, the dry ice and compressed air are delivered through different hoses. One-hose systems provide a more aggressive cleaning.
Some manufacturers do not want to depend on suppliers for dry ice. To produce their own dry ice pellets, they need additional pieces of equipment:
- Dry ice pelletizer: These machines turn liquid carbon dioxide (stored into pressurized tanks) into solid dry ice, pressurizing it and cutting it into the required size.
- Carbon dioxide: Carbon dioxide can be bought in liquid form, where it is stored at a high pressure (about 73.8 psi), which is the only way carbon dioxide can be in the liquid form. It can also be retrieved from the air (in small quantities) using additional pieces of equipment (like a CO2 recovery system).
- Dry ice bagging machine: The machines are used to package dry ice pellets after production by placing them in plastic bags to prevent waste. Different bag sizes are available to store different amounts of dry ice.
Laser Cleaning: An Alternative to Dry Ice Blasting
Laser cleaning can be used to remove contaminants from surfaces with the sheer power of light, but it is limited to metal surfaces. The process can remove all types of contaminants, including oil, dust, corrosion, oxides, electrolytes, and coatings.
Compared to dry ice blasters, laser cleaners are faster, more precise, less noisy, easier to integrate, cleaner for the environment, and have lower operating & maintenance costs.
Unlike dry ice cleaning, laser cleaning can generate a texture that improves adhesion. Lasers are used to prepare or clean surfaces for applications like:
- Welding
- Bonding
- Coating and painting
- Thermal spray coating
Laser cleaning solutions include automated and manually operated machines. If you want to learn more, contact our laser experts today.
