Ventilation – Fire damper
Reexamination Certificate
1999-08-23
2001-05-01
Joyce, Harold (Department: 3749)
Ventilation
Fire damper
Reexamination Certificate
active
06224481
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to air/smoke/fire dampers. In particular, it relates to dampers which can be controlled to be set and reset (i.e., closed and opened) locally or remotely under power, and which seal the damper under pressure when the damper blades are in the closed position, and which can modulate pressure levels to prevent smoke migration into designated non-smoking safety zones. It is also capable of setting normal operating building pressure differentials for cleaner air environments.
2. Background Art
Non-butterfly type dampers which can be closed automatically upon actuation by a heat-sensitive or other device are well-known in the art. Some such non-butterfly type dampers snap closed under either their own weight (i.e., gravity), or by mechanical force provided by springs.
As the art developed, external controls were devised to activate these dampers. Further, controls were also developed to cause the damper to be reset, that is, to be open in a ready position for heat responsive actuation in the event of fire or smoke conditions. A disadvantage of these prior art dampers is that they typically are activated by a separate device's exposure to the heat from a fire. As a result, they may disable the drive linkage making reactivation. Therefore, a substantial amount of smoke and even flames may pass through the damper before it is activated. It would be advantageous to have a damper system that could be activated well in advance of the fire or smoke to more effectively prevent either from passing through the damper.
An additional disadvantage associated with prior art systems is that these gravity or spring driven devices are slow to actuate. As a result, by the time the dampers are closed, substantial amounts of smoke, beat and even flames may have passed the damper and spread through the building.
In addition to problems caused by slow heat responsive closure, dampers which are then closed by gravity or spring driven devices do not always form an effective seal. As a result, even though the damper may be in the closed position, smoke and flames may penetrate the damper and spread to other parts of the building, causing property damage and personal injury. It would be desirable to have dampers that form an effective seal rather than merely temporarily contain either the fire or the progress of smoke, and to do so instantly, such that the potential damage from smoke, heat and flames is reduced.
While addressing the basic desirability of using dampers, the prior art has failed to provide a damper which can be powered closed well before advancing smoke and fire arrives, which creates an effective seal, and which can be sealed rapidly by a powered drive mechanism.
SUMMARY OF THE INVENTION
A powered damper assembly in which operation of the damper blades is controlled by a powered actuator. The powered actuator can be powered by a pneumatic drive, a electric owner controlled drive, or any other suitable power source. In one embodiment, the powered actuator is attached to the damper blades via a rotating shaft which is rotated by the powered actuator and which causes cycling of the damper blades to move between the open and the closed position, and be set in intermediate positions to set up controlled pressure environments by modulating the air flows. In another preferred embodiment, an electric motor powered actuator drives the shaft to cycle the damper blades between the open and the closed position. In another embodiment, the actuator can be self-controlled by a heat responsive device, which allows the damper to be closed by a spring or an automatically resetting motor control. The remote control system can communicate with the damper controls via a hard wired connection, or alternatively, via radio transmission. The powered actuation provides sufficient force to operate against heated air flow and to seal the damper tightly which in turn prevents both the smoke and fire from easily penetrating the damper. The butterfly blade design lends itself more readily to round or oval duct configurations, and this operating mechanism was developed to suit the “butterfly” damper design. The butterfly design also (when properly positioned) automatically uses the air fan or fire pressure to enhance the seal by pressing the ends of the pivoted blades against the frame.
REFERENCES:
patent: Re. 32362 (1987-02-01), McCabe
patent: 4545363 (1985-10-01), Barchechat et al.
patent: 4559867 (1985-12-01), Van Becelaere et al.
patent: 4818970 (1989-04-01), Natale et al.
patent: 4993313 (1991-02-01), Newman et al.
patent: 5533929 (1996-07-01), Attridge, Jr.
patent: 5728001 (1998-03-01), Attridge, Jr.
Benasutti Frank J.
Boles Derek S.
Joyce Harold
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