Process

Equipment functions

During CO2 snow blasting, liquid CO2 is converted into solid CO2 snow particles with a diameter of between 1 to 100 µm, via thermodynamic and physical processes. These CO2 snow particles from dry ice have a temperature of -78.5 °C. CO2 snow particles are added proportionally to the compressed air. The acceleration of the particles is achieved through the compressed air flow in a special nozzle. It is possible to generate a homogeneous free jet by observing the flow, temperature and pressure conditions. Dependant on the nozzle used, different jets can be generated. For example a round nozzle generates a round jet of high accuracy and cleaning power whereas the flat nozzle generates a wide (up to 100 mm) and constant jet with an even cleaning efficiency. These CO2 snow jets clean and prepare surfaces. As the CO2 snow particles hit the surface, they sublime abruptly.

Cleaning mechanism

CO2 snow blasters enable surfaces to be treated gently. Cleaning using CO2 snow blasting is based on a complicated process mechanism involving temperature, blasting and solvent effects. CO2 snow particles cool the impurities abruptly which leads to a separation of these from the substrate. Due to the sudden sublimation of the CO2 particles, small surges in pressure are created. These pressure surges release micro impurities on surfaces, even in the pores. By blasting along the surface impurities are removed from the surface and disposed of. A precision cleaning, especially for oil and grease, is accomplished due to the physical solubility of the organic properties in CO2. The compressed air flow aids the removal of the impurities.

Disposal

Following the CO2 snow blasting, the blown-off impurities are now particles and/or aerosols in the exhaust air. Depending on the application, an exhaust fan and filter can improve the quality of the surface to be cleaned. Without an exhaust fan, the dry impurities can be collected in the cleaning area and then either be vaccuumed or swept away. The blasting media itself has reversed to its gaseous state, so that only the impurities have to be disposed of.