Dry ice blasting
Dryice blasting is an industrial cleaning method that uses abrasive spray, which accelerates dry ice particles with compressed air to remove unwanted surface pollutants. There are other similar methods of blasting (eg: sandblasting, sodablasting). Dry-ice blasting leaves no chemical residue as dry ice sublimates at room temperature.
Dry ice is carbon dioxide (CO2) frozen into pellets. The actual dry-ice pellets are quite soft and much less dense than other media used in blasting-cleaning (eg: sand or plastic pellets). Upon impact, the pellet sublimates immediately, transferring minimal kinetic energy to the surface producing minimal abrasion. The sublimation process absorbs a large volume of heat from the surface. The effectiveness of this process depends on the thermal conductivity of the substrate.
Dry ice blasting generally uses one of two delivery systems to combine compressed air with ice and accelerate particles out of the delivery nozzle:
- Single-hose technology – developed by Cold Jet, LLC in 1986. It uses a single hose to deliver air blasts and dry ice. The single hose system can use a longer hose than the double-hose, without a significant drop in pressure when the ice leaves the hose. Single-hose systems are used when the surface to be cleaned is vertical or at a greater height than the hopper and gas compressor.
- Two-hose dry-ice blasting – developed before the single-hose system. Compared to the single hose system, the two-hose system delivers ice pellets with less force (approximately 5% for a given air supply). Two-hose systems are generally less costly to produce due to a much simpler delivery system and they allow finer particles of ice to be delivered with lower velocity. The latter properties allow for more delicate surfaces to be cleaned.
Numerous benefits come with the use of dry ice blasting. This portable technique can save time due to reductions in the breakdown and assembly of equipment. Dry-ice blasting is very useful in cleaning food processing equipment to effectively decontaminate surfaces of Salmonella enteritidis, E. coli and Listeria monocytogenes such that these microorganisms are not detectable using conventional microbiological methods.
The EPA (Environmental Protection Agency) recommends dry ice blasting as an alternative to many types of solvent-based cleaning. From simple objects to objects with differing, complex geometries at once, dry-ice blasting is the best cleaning method. Dry-ice blasting can be used to clean many different thing including turbines and generators used in the power generation industry; fire, soot and smoke damage; printing machins, mold etc.
When reaching at concentrations above 1%, CO2 becomes extremly toxic and can also lead to running aut of oxygen resulting asphyxia, if equipment is not used properly in a ventilated area. Wering protective gloves , ears and eyes protection is a must in this situation, since at normal pressure dry ice is −78 °C (−108 °F). Compared to other blasting-cleaning methods, dry ice blasting produces fewer waste products.