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Article: Building Exterior Cleaning with Dry Ice Blasting (building maintenance)

In 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.

 What 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.

What 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.

Environmentally Friendly

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 buildings:

            In 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. 1

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.

Other 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.

Safety

So, 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. 

A Cleaner Clean

When 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 cleaning maintenance.

Operating Details

As 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.

Cleaning 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. 

Dry 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.

For 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.

 For more information about this technology please contact:

Jeffrey Lapointe

President/CEO
RSG Technologies, Inc.
Voice: 800-513-0113
Fax: 603-299-0364

Email: info @ rsg-technologies.com

1  King County Stormwater Pollution Prevention Manual, January 2005

For Current Pricing, Service Contract Options, and Facility Requirements on ICEsonic Dry Ice Blast Cleaning Products: http://www.rsg-technologies.com/

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