Dry ice-blasting is a form of abrasive blasting, where dry ice, the solid form of carbon dioxide, is accelerated in a pressurized air stream and directed at a surface in order to clean it.
The method is similar to other forms of abrasive blasting such as sand blasting, plastic bead blasting, or sodablasting but substitutes dry ice as the blasting medium.Dry-ice blasting leaves no chemical residue as dry ice sublimates at room temperature.
The ice used can be in solid pellet or shaved ice block forms. The shaved ice block produces a less dense ice medium and is more delicate than the solid pellet system.
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 was developed by Cold Jet, LLC in 1986, and uses a single hose to deliver air blasts and dry ice. The single hose system can use a longer hose than the double-hose counterpart without a significant drop in pressure when the ice leaves the hose. The additional power comes at the cost of increased complexity. Single-hose systems are used when the surface to be cleaned has a heavier build-up or when the surface to be cleaned is vertical or at a greater height than the hopper and gas compressor.
Two-hose dry-ice blasting was developed before the single-hose system. Compressed air is delivered in one hose, and ice pellets were sucked out of a second hose by the venturi effect. Compared with a single-hose system, the two-hose system delivers ice pellets with less force (approximately 5% for a given air supply) than a single-hose system. Theoretically two-hose systems have a limit to the vertical distance between the machine and applicator. This limit however is well in excess of 25 feet. 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 as the late combination of warm air with cold ice results in less sublimation in the hose. The latter properties allow for more delicate surfaces to be cleaned.