Gas separation: processes – Filtering
Reexamination Certificate
1999-12-30
2001-11-27
Smith, Duane S. (Department: 1724)
Gas separation: processes
Filtering
C055S385200, C055S467000, C055S486000, C096S135000, C096S142000
Reexamination Certificate
active
06321637
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a filter module for use with an air-purifying system. More particularly, it relates to a low-profile filter module configured for convenient installation in commercial settings.
In recent years, there has been a growing interest to improve environmental air conditions in homes and in commercial settings, such as offices, restaurants, taverns, bowling alleys, hospitals, laboratories, lavatories, and the like. As more information has been made available to the public concerning the hazards of indoor air pollution, there has been an increased demand for filtering devices that can be used to effectively improve air quality.
A self-contained, stand-alone air-cleaning or filtration unit is normally employed to clean air in both residential and commercial settings. Stand-alone air filtration units can assume a wide variety of forms, but generally include a housing maintaining one or more applicable filter materials and a fan or blower unit. The housing defines an inlet, at which the filter material(s) is disposed, as well as an outlet or exhaust port. Most commercial applications include a false ceiling, such that the housing is readily “hidden” above the ceiling, with only the inlet (or an associated grille) being visible to persons within the room. During use, the fan or blower unit is operated to draw room air through the filter via the inlet. The filter material or media removes undesirable air-borne particles and/or odors, such as dust, smoke, pollen, molds, etc. from the air stream. Following interaction with the filter material, the now “cleansed” air is forced, via the blower, back into the room through the outlet. A continuous intake and supply of air preferably generates a desired air re-circulation pattern within the room.
While the self-contained air-filtering device is well accepted, certain potential drawbacks have been identified. For example, in order to adequately filter and re-circulate air in an average-sized room (e.g. 2000-5000 square feet), the stand-alone unit must be relatively large. In other words, the blower unit or fan(s) is typically substantially sizable for creating adequate airflow or pressure differential, such as a 1 or 2 horsepower motor. Similarly, in order to remove different sizes and types of air-borne contaminants on a long-term basis, the filter is normally comprised of at least two filter medias, including a primary particulate filter and a sorbent material filter. The particulate filter is provided to remove air-borne particles and fibers, such as a high efficiency particulate arrestance (HEPA) filter. The sorbent material filter removes gaseous contaminants and odors, such as tobacco odors, volatile organic compounds (VOCs), etc. The most effective form of sorbent material filter includes a sorbent material, such as charcoal, potassium permanganate, or zeolite, in granular form. To facilitate long-term use in a commercial application, a relatively large volume of granular sorbent material is provided, on the order of at least 10 pounds.
Taken in combination, the large blower unit and several filter materials render the resulting air filtration unit relatively heavy and large. As a point of reference, a self-contained, commercial air filtration unit incorporating both a particulate filter and a sorbent material filter may weigh as much as 150 pounds and have a housing height on the order of 14 inches.
The above-described weight and size characteristics render installation or re-installation of a self-contained, commercial air filtration unit quite cumbersome. For many commercial applications, rooms (such as offices, smoking areas, etc.) are constantly reconfigured to meet the needs of different uses or occupants. While a location of an air filtration unit may be optimal for one room configuration, that same positioning may be highly inefficient for the new configuration. Under these circumstances, the bulky air filtration unit must be removed and re-installed to a new, more desirable location. Obviously, this is a difficult task.
A related concern arises with commercial settings employing a false ceiling to which the air filtration unit is installed. The building infrastructure associated with virtually all commercial settings includes a number of auxiliary equipment extending above, but in close proximity to, the false ceiling. For example, most commercial applications include sprinkler systems, electrical wiring, light fixtures, heating, ventilation, and air conditioning (HVAC) ducts, hot and cold water pipes, etc. The presence of this auxiliary equipment may reduce the space available for installation of the commercial air filtration unit. That is to say, due to the requisite height of the unit's housing, immovable auxiliary equipment may impede installation of the cleaning unit at a preferred location.
One potential solution to the above-described problems is providing the blower and filter as separate modules. The resulting modular air-cleaning system would afford the ability to more easily locate and relocate the now separate filter module. In theory, by forming the filter module to include only a housing and requisite filter material(s), the resulting filter module would have a reduced height as compared to a stand-alone air-cleaning unit. Likely due to the industry acceptance of self-contained air-cleaning units, as well as the engineering obstacles presented by a modular configuration, it is believed that no such product currently exists. In fact, only one potential system has been identified, advertised as being available under the trade name Crystal-Aire® by United Air Specialists, Inc. of Cincinnati, Ohio. According to a trade brochure, this air-cleaning system apparently includes separate blower and filter units designed to be connectable by a single duct. This configuration purportedly allows the blower unit to be installed apart from the filter unit. However, the blower unit has only one inlet and one outlet, such that the system is essentially restricted to a single filter unit. In theory, it may be possible to connect two or more filter units in series to the blower unit. Unfortunately, overall filter efficiency may be greatly reduced. In this regard, the blower unit and the filter unit are connected by a relatively large duct, described as being 16 inches in diameter. The filter module's housing must provide a correspondingly sized outlet port. As a result, regardless of type and/or configuration of filter materials, the required duct diameter dictates that the filter unit's housing have a height greater than 16 inches. In fact, the filter unit is advertised as having a height of 19 inches.
The above-described reliance upon a 16-inch diameter duct coincides with industry standards for commercial HVAC ductwork. Another commonly employed duct diameter is 12 inches. In either case, a resulting filter module in accordance with the advertised Crystal-Aire® system will have a height of at least 14 inches. As a result, even with the one identified modular design, it is highly likely that auxiliary equipment located above a false ceiling will impede installation of the filter module at a desired location. Notably, the cross-sectional area provided by the duct and therefore the filter unit's outlet port bears a direct relationship to the operational parameters of the blower unit. In particular, a reduction in the duct and outlet port cross-sectional area requires an increase in the operational speed (e.g., RPM) of the blower unit to achieve a desired airflow rate. While blower motors can undoubtedly be sized to satisfy most airflow requirements, elevated operational speeds result in increased noise levels. In other words, even if a smaller diameter duct were employed, the associated power increase required of the blower unit may result in unacceptable noise levels.
Air-purifying systems are extremely popular and beneficial. However, the standard “self-contained” design is highly inflexible, and may be difficult to install and/or reposition. While sugge
Bahn Richard R.
Monnens Patrick J.
Shanks Anthony E.
Dicke, Billig & Czaja P.A.
Honeywell International , Inc.
Smith Duane S.
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