DRY
ICE BLASTING
USAGE OF DRY ICE
IN DRY ICE BLASTING
Dry ice blasting is a relatively
new cleaning process using solid pellets
(known as dry ice). It is primarily used
for industrial use in a variety of applications.
The pellets sublimate (convert directly
from a solid blast pellet to a vapor) leaving
no residue, hazardous waste or toxic fumes.
Today, the dry ice method of cleaning is
quickly becoming favored for environmental
as well as production reasons. Because of
tremendous environmental regulations, industry
has needed to minimize wastes. Further,
there is a growing consciousness that many
are placing now on the global environmental
impact of their production practices. However,
these benefits are accentuated due to the
tremendous performance gains through dry
ice blasting -- little or no production
downtime, quality of clean and minimized
damaged to equipment.
Dry ice blasting is similar
to conventional shot blasting except that
the shot is replaced by pellets of dry ice
which literally disappear as soon as the
cleaning cycle is complete. The dry ice
particles are propelled to supersonic speed,
to impact and clean a surface. The particles
are accelerated by compressed air, available
from standard industrial compressors. When
the pellets impact on a substrate with a
tightly bonded layer of surface contamination,
or unwanted coating, the dry ice creates
a layer between the substrate and the surface
layer. Once between the surface layer and
the substrate, the pellets complete their
sublimation creating a large volume of Co2
gas which rapidly expands. The process provides
a dry and abrasion free clean, and because
the pellet media sublimates immediately
upon impact (turns from a solid to a gas),
there is no secondary waste disposal necessary.
Why is Dry Ice Blast
cleaning so effective?
Kinetic Energy:
As with traditional methods, the velocity
and mass of the media upon impact transfers
the required energy to the surface being
cleaned. Whilst this principle is, traditionally,
responsible for the majority of work in
blast cleaning, it only reflects one aspect
of Dry Ice Blast Cleaning.
Thermal Differential:
The surface temperature of Dry Ice upon
impacting the substrate surface is -78.6oC.
The temperature differential established
promotes contraction and expansion, which
aids the removal process.
Reverse Fracturing:
The Dry Ice particles sublimate immediately
upon impact and enter through the spaces
behind the contaminant at more than 550
times their original volume, pushing it
cleanly away from the surface being cleaned.
Dry Ice Blasting Compared
to Traditional Methods
The following two charts give a helpful
perspective of how dry ice blasting compares
with the traditional cleaning methods --
sand, blasting, solvents, and others:.
Dry Ice Blast Cleaning
Comparison Chart
Blasting
Cleaning Technique |
Waste
for Disposal |
Abrasive
|
Toxic
|
Electrically
Conductive |
Performance
Comparison |
Dry Ice
|
No |
No |
No |
No |
Excellent |
Sand |
Yes |
Yes |
No |
No |
OK |
Glass Beads
|
Yes |
Yes |
No |
No |
OK |
Walnut Shells
|
Yes |
Yes |
No |
No |
Limited |
Steam |
No |
No |
No |
Yes |
Poor |
Solvents
|
Yes |
No |
Yes |
Yes |
Limited |
* Each of these blast cleaning
materials becomes contaminated upon contact
if used to clean hazardous objects. When
that happens, these materials are then classified
as toxic waste requiring safe disposal.
The above chart compares
the various methods of cleaning with the
dry Ice blasting. Each type of cleaning
finds usage in specific industries.
CLEANING METHOD COMPARISION
Issue |
Traditional |
Dry
Ice Blasting |
| Equipment Downtime |
Cleaned in dedicated cleaning area;Disassembly/reassembly;
Drying time required |
Equipment can be cleaned in place;
Dry process - equipment restart immediately
after cleaning |
| Hazardous waste |
Cleaner becomes and treated as a secondary
contaminant |
No additional contaminant .Dry ice
sublimates with contact with targeted
surface |
| Labor Hours |
Intensive hand scrubbing; Lengthy
cleanings; Follow-up cleaning-up can
be lengthy |
Dramatically reduced - often completed
in a quarter of time or better |
| Quality of Cleaning |
Poor to average |
Excellent |
| Potential Equipment Damage |
Grit abrasions; Grit contamination;
Movement of equipment to and from cleaning
area |
No equipment damage; Preventive maintenance
very realistic as labor hours are significantly
less |
| Safety |
Health threats from solvents; Water-based
cleaning pose hazards around electrical
equipment; |
Standard safety precautions; Dry process
- safe around electrical equipment |
| Cost |
Cleaner becomes additional hazardous
waste; expensive solvents; |
Minimal - cost of dry ice |
APPLICATIONS:
Dry ice blast cleaning
applications are available to a multitude
of industries offering tremendous value.
In addition to the general benefits mentioned,
dry ice blasting has specific benefits to
some of the following industries:
Airlines/Aerospace |
Utilities |
Automotive |
Electrical |
Foundries |
Food Processing |
General Maintenance |
Mass Transit |
Marine |
Pharmaceuticals |
Plastics |
Printing/Plating |
Pulp and paper |
Rubber |
Benefits Of DRY ICE
BLASTING :
1 - Decreased Downtime through
Cleaning In-Place
2 - Faster and More Thorough Cleaning
3 - Elimination of Equipment Damage
4 - Reduction or Elimination of Solvents
5 - Reductions in Waste Disposal
6 - Increased Safety
