Cleaning and liquid contact with solids – Processes – Using solid work treating agents
Reexamination Certificate
2000-07-28
2002-10-22
Gulakowski, Randy (Department: 1746)
Cleaning and liquid contact with solids
Processes
Using solid work treating agents
C134S022100, C134S022110, C134S022120, C015S406000
Reexamination Certificate
active
06468360
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for cleaning heating, ventilating, and air-conditioning (HVAC) ducting.
2. Description of Related Art
In structures and/or vessels having ducted air ventilation systems, it is well known that during normal operation, debris will collect and be deposited in the ducts. These deposits can often include such contaminants as dirt, dust, hair, clothing fibers, grease, oil, left-over construction materials, decaying organic matter and various organisms such as dust mites, bacteria, fungus, viruses, or pollen.
Not only does this debris represent a health hazard to individuals who breathe the air from the ducts but it also contributes to conditions such as allergies, asthma, or respiratory disorders. The collection and deposit of excessive amounts of debris within a particular ventilation system affects the efficiency of the ventilation system. Furthermore, large amounts of dirt, grease, oil, or lint can result in ventilation duct fires, which are extremely difficult to extinguish.
Therefore, in order to minimize health and other hazards, and to ensure efficient airflow, it is necessary for ventilation ducts to be cleaned periodically to remove the deposited debris. However, if a particular ventilation system has not been cleaned for quite some time or if the debris consists of, for example, grease or oil, the deposits of debris inside the ventilation ducts may be quite difficult to remove.
Although ventilation ducts can be cleaned by hand using various brushes, scrapers, and chemicals to remove any accumulated debris, hand cleaning is time consuming and in most cases requires that the ventilation system be dismantled, cleaned, and reassembled. Thus, various apparatuses and methods have been developed over the years for removing deposited debris from ventilation ducts. These debris removal apparatuses have traditionally used one of two methods to clean ventilation ducts. The first method employs a mechanical means to remove the deposited debris. For example, Franklin, Jr., et al. (U.S. Pat. No. 4,792,363) discloses a vent cleaning system that includes a brush that is rotated by a flexible shaft that is concentrically disposed in a flexible tubular vacuum conduit, so that dust can be dislodged from a vent wall and vacuumed into the vacuum conduit. Likewise, U.S. Pat. No. 1,869,730 to Antle, U.S. Pat. No. 5,572,766 to Matsuura et al., and U.S. Pat. No. 5,655,256 to Hendrix et al. also disclose the use of brushes to clean ventilation ducts.
The second method that has traditionally been used to remove deposited debris from ventilation ducts has utilized either compresses air or fluid. Piguillet (U.S. Pat. No. 5,942,044), for example, discloses a method for cleaning and treating a ventilation duct wherein a nozzle is propelled by the reaction thrust of a pressurized fluid emitted from several hollow arms of a propelling device.
In Jones (U.S. Pat. No. 5,966,773), a duct cleaning system is disclosed that includes an air compressor connected to a manifold with at least one line coupled to an air gun while another line is connected to the duct cleaning system providing a pressurized exhaust to dislodge and remove debris from the ducts. Likewise, U.S. Pat. No. 5,003,998 to Collett, U.S. Pat. No. 4,968,333 to Ellis et al., and U.S. Pat. No. 4,468,835 to Rhodes also use compressed air and various nozzles to clean deposited debris from ducts.
Similarly, U.S. Pat. No. 4,508,577 to Conn, et al., U.S. Pat. No. 4,141,753 to Creed, and U.S. Pat. No. 5,383,975 to Faxon disclose a fluid or pressurized medium emitting apparatus and method for cleaning material from the inside of ducts or conduit.
It has been recognized that solid Carbon Dioxide (CO
2
), or “dry ice”, can be used as a “sandblasting” medium. For example, U.S. Pat. No. 4,038,786 to Fong discloses the use of pellets of material capable of subliming under conditions of use in a sandblasting process. Unlike other sandblasting medium, which present the possibility of atmospheric contamination and must be collected or cleaned up after being used, dry ice particles disappear as gaseous carbon dioxide after having been used in sandblasting.
Therefore, the use of dry ice in sandblasting presents no cleanup problems with respect to the sandblasting medium and there is no risk of adverse atmospheric contamination because ambient air already contains carbon dioxide and carbon dioxide gas is readily dispersed within ambient air.
SUMMARY OF THE INVENTION
Although a variety of methods and apparatuses do exist for cleaning ventilation ducts, no particular system has received widespread acceptance. The known systems and methods are quite complex, and require the use of either various blowers or blower modules to provide a pressurized exhaust or strong vacuum devices to remove the debris from the ventilation ducts once the debris has been dislodged from the duct surfaces. Often, a duct-cleaning contractor must operate vacuum equipment, such as, for example, vacuum equipment located in the contractor's truck or van, in order to remove the loosened debris.
Hand cleaning, as well as certain chemical or mechanical methods of duct cleaning, can damage the ventilation ducts by scratching, wearing away, grinding down, or corroding the interior surfaces of the ventilation ducts. Unfortunately, scratches can provide areas for debris to cling to as the ventilation system operates, and any damage to the ventilation ducts will degrade the structural integrity of the ventilation ducts.
Additionally, the traditional duct cleaning systems and methods lack the ability to effectively and efficiently clean certain duct areas, such as, comers or areas around screw heads or rivets. Likewise, many of the known systems and methods are difficult to adapt for cleaning ventilation systems that are made up of both round cross sections (typically found in hot air delivery portions) and rectangular cross sections (typically found in cold air return portions).
Furthermore, when a fluid is used to dislodge the debris from a duct surface, the dislodged debris becomes mixed with the fluid and both the dislodged debris and any remaining fluid must be removed from the duct system before the system can be operated.
Accordingly, this invention provides a method for cleaning ventilation ducts that uses dry ice blasting to remove debris from the surface of the ventilation ducts.
In various exemplary embodiments, this invention separately provides a method for cleaning ventilation ducts that uses an existing ventilation system to provide sufficient vacuum power for removing dislodged dirt and debris from ventilation duct work.
In various exemplary embodiments, this invention separately provides a method for cleaning ventilation ducts that eliminates the need for additional vacuum apparatuses.
This invention separately provides a method for cleaning ventilation ducts that allows ventilation ducts to be cleaned without being completely dismantled or removed.
This invention separately provides a method for cleaning ventilation ducts that removes debris from ducts without compromising the structural integrity of the ventilation system.
This invention separately provides a method for cleaning ventilation ducts that allows debris to be removed from all of the surfaces of the ventilation system, including comers and the areas around screw heads and rivets.
In accordance with the systems and methods of this invention, one exemplary embodiment of the systems and methods for cleaning ventilation ducts according to this invention uses a dry ice blasting system that is adapted to blast debris from the surfaces of ventilation ducts. Basic dry ice blasting systems are well known as described above. The method of this invention further includes the use of existing duct ventilation airflow to evacuate dislodged debris and a filtration system attached to the exhaust of the existing duct ventilation to capture the dislodged debris.
REFERENCES:
patent: 4038786 (1977-08-01), Fong
patent: 4482392 (1984-11-01), Pollock et
Gulakowski Randy
Kaufman & Canoles
Smetans J.
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