Procedures
The blasting process
Our dry-ice-blasters are so-called two-hose systems which operate according to the venturi principle.
One
hose feeds compressed air to the gun. A second hose supplies dry ice to
the gun and the compressed-air jet by way of the venturi principle. (Picture
1)
The impact of the pellets on the surface causes it to snap-freeze. The dirt sticking onto the surface embrittles. As the base material and the dirt layer that is to be removed consist of different materials their thermal expansion co-efficient is not identical which is why they respond differently to the snap-freezing process.
Mechanical tensions, also called thermo-electric voltages, will build up at the border areas and cause the dirt layer on the base material to come off. (Picture 2)
The kinetic energy causes the dry-ice pellets to sublimate immediately upon impact which results in a fast and extreme expansion of the dry ice volume. In addition, the pellets blast off the residues in a series of »mini explosions«. (Picture 3 )
Dry blasting is non-toxic, not flammable and does not conduct electricity.
Conventional blasting methods
Blasting
agents destroy the surface. The resulting waste mixes with the residues
of the contamination and must be disposed of. (Picture 4)