Ventilation – Fire damper
Reexamination Certificate
2000-04-29
2002-09-10
Joyce, Harold (Department: 3749)
Ventilation
Fire damper
C454S342000
Reexamination Certificate
active
06447393
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 be operated partially closed to modulate pressure levels and to prevent smoke migration. This invention 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. See, for example, U.S. Pat. Nos. 4,301,569 and 4,442,862.
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 reopened to 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 have virtually unsealable multiple vanes that are activated by a separate device exposed to the heat from a fire. As a result, the heat may disable the drive linkage, thus interfering with reactivation. Also, a substantial amount of smoke and even flames may pass through the damper before it is activated (if at all). It would be advantageous to have a simple two blade butterfly type damper system that could be activated more reliably in advance of the fire or smoke passing through the system, to more effectively prevent either from passing through the damper.
In addition to problems caused by complicated heat responsive closure, dampers which are 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 pass through the damper and spread to other parts of the building. 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.
Typical multi-blade dampers can be actuated to control flow by a pneumatic actuator. However, it is desirable to have an override for the pneumatic control which will close the damper in case of a fire.
Also in the multi-blade damper, if the blades are pivoted in their longitudinal center, the air and heat does not help to keep the seal shut. Rather, pressure on one side of the pivot of the blade tends to force it open, while pressure on the other tends to force it closed. It is, therefore, desirable to have a simple end pivoted two blade damper which is forced even tighter closed and sealed under pressure.
It is further desirable to have a damper system in which the damper can be partially closed or opened, in order to modulate the pressure in the system. For example, it may be desirable to have more pressure in one room than another and to be able to adjust the opening in the damper, remotely, so as to affect the amount of air passing therethrough.
The prior art has failed to provide a damper which can be powered closed well before advancing smoke and fire arrives and have failsafe spring closure on power failure, which creates an effective seal, which can be sealed rapidly by a powered drive mechanism, and which can be partially opened and closed to modulate the pressure in the system in which the damper is used and have a simple two blade end pivoting with direct drive linkage for round and rectangular dampers.
SUMMARY OF THE INVENTION
My invention comprises a butterfly configured 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 user controlled drive, or other suitable power source. In one embodiment, an electric powered actuator is attached to the damper blades via a rotating shaft. The actuator causes cycling of the damper blades to move them between an open and a closed position, and/or causes them to be set in intermediate positions to set up controlled pressure environments by modulating the air flow through the damper. In another preferred embodiment, a pneumatic 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. A 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 passing through the damper. This design lends itself more readily to round or oval duct configurations. This configuration provides for a better seal in the case of the fully closed position of the blades.
REFERENCES:
patent: 3697142 (1972-10-01), Fortier
patent: 4273283 (1981-06-01), Edwards
patent: 5456633 (1995-10-01), Choi
patent: 5462485 (1995-10-01), Kinkead
patent: 5590830 (1997-01-01), Kettler et al.
patent: 5971067 (1999-10-01), Rayburn et al.
Bensautti Frank J.
Boles Derek S.
Joyce Harold
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