Ventilation – Having inlet airway – Including specific air distributor
Reexamination Certificate
1999-07-13
2001-08-28
Joyce, Harold (Department: 3749)
Ventilation
Having inlet airway
Including specific air distributor
C454S296000, C454S306000, C454S334000
Reexamination Certificate
active
06280320
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention generally pertains to flexible fabric air ducts and more specifically to a frame that supports the duct when it is deflated.
2. Description of Related Art
Ductwork is often used to convey conditioned air (e.g., heated, cooled, filtered, etc.) discharged from a fan and to distribute the air to a room or other areas within a building. Ducts are typically formed of rigid metal, such as steel, aluminum, or stainless steel. In many installations, ducts are hidden above suspended ceilings for convenience and aesthetics. But in warehouses, manufacturing plants and many other buildings, the ducts are suspended from the roof of the building and are thus exposed. In those warehouse or manufacturing environments where prevention of air-borne contamination of the inventory is critical, metal ducts can create problems.
For example, temperature variations in the building, or temperature differentials between the ducts and the air being conveyed can create condensation on both the interior and exterior of the ducts. The presence of condensed moisture on the interior of the duct may form mold or bacteria that the duct then passes onto the room or other areas being supplied with the conditioned air. In the case of exposed ducts, condensation on the exterior of the duct can drip onto the inventory or personnel below. The consequences of the dripping can range anywhere from a minor irritation to a dangerously slippery floor for the personnel, or complete destruction of the products it may drip on (especially in food-processing facilities).
Further, metal ducts with localized discharge registers have been known to create uncomfortable drafts and unbalanced localized heating or cooling within the building. In many food-processing facilities where the target temperature is 42 degrees Fahrenheit, a cold draft can be especially uncomfortable and possibly unhealthy.
Many of the above problems associated with metal ducts are overcome by the use of flexible fabric ducts, such as a DUCTSOX by the Frommelt Safety Products Corporation of Milwaukee, Wis. Such ducts typically have a flexible fabric wall (often porous) that inflates to a generally cylindrical shape by the pressure of the air being conveyed by the duct. Fabric ducts seem to inhibit the formation of condensation on its exterior wall, possibly due to the fabric having a lower thermal conductivity than that of metal ducts. In addition, the fabric's porosity and/or additional holes distributed along the length of the fabric duct broadly and evenly disperse the air into the room being conditioned or ventilated. The even distribution of airflow also effectively ventilates the walls of the duct itself, thereby further inhibiting the formation of mold and bacteria.
However, in many cases, once the room's conditioning demand has been met, the air supply fan is turned off until needed again. When the fan is off, the resulting loss of air pressure in the duct deflates the fabric tube: causing it to sag. Depending on the application and material of the fabric, in some cases, the sagging creates a poor appearance or may interfere with whatever might be directly beneath the duct.
SUMMARY OF THE INVENTION
In order to inhibit a fabric air duct from sagging when deflated, a frame is provided to maintain a flexible fabric outer casing of the duct in a generally expanded shape, even when the duct's interior and exterior air pressures are the same. The fabric outer casing is air-permeable to evenly disperse air into an area being served by the duct and is removable from the frame to facilitate washing the fabric and reinstalling it afterwards.
Providing a fabric air duct with a frame that maintains a flexible outer casing in a generally expanded shape may inhibit the growth of mold and bacteria within the casing at times when there is no airflow through the duct.
A frame that maintains a fabric air duct in a generally expanded shape reduces the extent to which the fabric sags when the duct's interior and exterior air pressures are the same.
In some embodiments, adjustable air discharge openings are incorporated in the same frame that helps hold the air duct's fabric outer casing in a generally expanded shape.
An air duct that includes a frame with a removable outer casing made of fabric allows the fabric to be periodically machine washed and reinstalled on the frame.
One embodiment of a fabric duct whose frame holds an outer casing open when deflated further allows the casing to be removed without having to slide it out from one end of the frame where space may be limited in some applications.
REFERENCES:
patent: 2423241 (1947-07-01), Kurth et al.
patent: 3357088 (1967-12-01), Hoffman et al.
patent: 5123595 (1992-06-01), Koss
patent: 0 175 892 (1986-04-01), None
patent: 0 840 072 A2 (1998-05-01), None
patent: 0 899 519 A1 (1999-03-01), None
patent: 2 713 317 (1995-06-01), None
patent: 63-3143 (1988-01-01), None
patent: 3-110342 (1991-05-01), None
International Search Reportcorresponding to International application Ser. No. PCT/US00/19145, dated Oct. 17, 2000, 8 pages.
Boffeli Thomas J.
Paschke Nicolas B.
Joyce Harold
Marshall O'Toole Gerstein Murray & Borun
Rite-Hite Holding Corporation
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