our current age where environmental concerns regarding industrial and
commercial cleaning are growing, companies need to turn to
alternative cleaning methods. Traditional
methods, specifically pressure washing, are under increased scrutiny.
What are valid alternatives?
For building exterior cleaning, one very valid option is
dry ice blast cleaning.
Is Dry Ice Blasting?
It is a process in which a blasting gun fires dry ice particles
(rice-sized) at supersonic speed to impact and clean a surface. The
particles are accelerated by compressed air, just as with other blasting
systems. Upon impact the dry ice sublimates (converts from a solid to a
gas without passing through a liquid phase) expanding 400 to 800 times
its volume as it does so. The kinetic energy plus volume expansion cause
the targeted material to be immediately removed. The cleaned surface is
left in excellent condition with no additional waste to clean.
Is Dry Ice?
Further, dry ice pellets are made by taking liquid carbon dioxide
(CO2) from a pressurized storage tank and expanding it at ambient
pressure to produce snow. The snow is then compressed through a die to
make hard pellets. The pellets are readily available from most dry ice
suppliers nationwide. For dry ice blasting, the standard size is
1/8-inch high-density dry ice pellets.
At the beginning of the article, the need to find alternatives to
pressure washing was briefly mentioned The fact that dry ice blast
cleaning utilizes a completely dry process is an extremely valuable
benefit. Water is eliminated. By doing so, it leaves no secondary
contaminant. No runoff or waste collection issues are associated
with dry ice blast cleaning.
Dry ice is an outstanding environmentally friendly
cleaning media. Very often, the CO2 sold by manufacturers such as
Airgas and Praxair is recycled. Therefore, no new CO2 is emitted
into the atmosphere.
Also, CO2 is a natural element of the earth, comprising about 0.03% of
our atmosphere. All humans and animals give off CO2 which is used by
plants to help them grow. The CO2 industry and its users have a
very minimal role in adding to the greenhouse effect and as legislation
continues with stricter air and water regulations, dry ice blasting will
step forward to replace harmful detergent and solvent pollution and
their disposal problems.
Pressure Washing Concerns
What are the primary issues regarding pressure
washing? Though it has been
a favored cleaning method for exterior structures for decades,
governmental agencies, however, are becoming more and more alarmed at
its effects and are writing safeguards on its usage.
For example, in the King County (Seattle, WA)
Storm water Pollution Prevention Manual published in January 2005, it
notes that pressure washing can, “readily degrade water quality as the
runoff and loosened solids typically travel directly into the storm
drainage system.” 1 The
report notes the following requirements for pressure washing of
situations where soaps or detergents are used and the surrounding area
is paved, pressure washers must use a water collection device that
enables collection of wash water and associated solids.
A sump pump, wet vacuum or similarly effective device must be
used to collect the runoff and loose materials.
The collected runoff and solids must be disposed of properly.
Strict guidelines as noted above will only become more commonplace
throughout the United States as awareness of pressure washer-related
pollution grows. Dry ice blasting is a common sense and easy to
use cleaning alternative.
Benefits Pertaining to Cleaning Building Exteriors
Beyond, the environmental issue, there are a number of other benefits
of dry ice blast cleaning pertaining to cleaning building exterior
cleaning. They include the following:
- Eliminates slip hazard material
- Eliminates use of dangerous solvents
- Acts as a natural biocide
- Electrically non-conductive
- Removes graffiti, mold, algae and other organic substances
- Cleans steam or gas turbine engines, chillers, condensing units,
and storage tanks
- Removes or leaves in place existing coatings, whichever is desired
- Reduces damage and wear to building surfaces.
dry ice blast cleaning is truly beneficial from a safety vantage point
as noted above for several reasons. The risk of slippage as with
pressure washing is eliminated.
Also, the risk of electrical shock is dramatically reduced.
Further, when compared to using chemicals, dry ice eliminates the
concern over toxic fumes.
removing organic materials off exterior siding, dry ice media offers a
more effective clean. Dry
ice is –109o
F. The severe cold is
sufficient to kill all organic material it comes in contact with.
Again, this includes all forms of mold and algae.
By doing so, when dry ice blasting removes materials off building
walls, it completely removes the organic material’s root structure
thereby generating a longer lasting clean and reducing the frequency of
for air system requirements, a large number of applications using dry
ice blasting equipment only require between 80 to 100 psi and 120 to 150
CFM. An evaluation of system air is usually recommended to determine if
the facility has sufficient capabilities to run dry ice blasting
equipment at the levels desired for each specific application. For
building exterior cleaning, a stand alone diesel compressor is typically
used and would require a 185 CFM tow behind compressor.
If airline beyond 100 feet is required, a larger compressor will
likely be necessary to maintain sufficient pressure.
removal rates of organic materials off building exteriors using dry ice
are typically 5 square feet per minute or better.
Usage can range regularly from 60 to 100 lbs or more per hour.
ice pellets are readily available throughout the US from a number of
different national suppliers. Dry
ice can either be delivered by the supplier to the job site or you can
schedule to pick up the media with your own truck.
The media is usually delivered in 500 lb (or larger) containers.
It can easily be transferred from its storage container using a
scoop or small shovel and then poured into an intermediary pail to be
brought and emptied into the hopper of the dry ice blasting machine.
safety equipment, ear protection is necessary.
Also, because the temperature of dry ice can be as low as –79oC
(-109 oF), insulated gloves should always be worn when
working with it. Face
shields are also required.
more information about this technology please contact:
RSG Technologies, Inc.
info @ rsg-technologies.com
King County Stormwater Pollution Prevention Manual, January 2005