Abstract:
Potentially harmful particulate materials introduced into an airflow drawn into a structure&#39;s HVAC system are sensed by sensors provided on an intake fan and protective measures are taken in response to such sensed presence.

Description:
FIELD AND BACKGROUND OF INVENTION 
       [0001]    The air intake components of traditional heating, ventilation, and air conditioning (HVAC) systems found in manufacturing and office facilities and in vehicles such as automobiles and train cars are vulnerable to biological or chemical agent attack. Some structures have outdoor air intake vents or portals at ground level, at mid-height, or on the roof of the structure. Depending upon the location of the actual air intake vents, these potential portals of attack are readily accessible. Biological agents, such as anthrax, small pox, SARS, influenza, TB, and other airborne infectious agents, can be readily introduced and disbursed throughout the buildings via their HVAC systems, as can harmful gases introduced as droplets of liquid. 
         [0002]    Traditional HVAC systems are simple duct works with filtration that is not able to effectively remove these airborne agents. They were designed for maximum airflow efficiency, economy, and the removal of normal airborne particulates. Attempted protection by use of additional filtration such as high efficiency particulate (HEPA) is problematic as HEPA filters are fragile and must be frequently replaced. If used in an effort to intercept harmful materials, the discarded filters must be treated as hazardous waste if biological or toxic agents have been retained. Electrostatic filtration may be proposed as an alternative, using charged plates to remove particulates from the air stream and sequester them on the charge plates. These plates must be cleaned regularly to function. If infectious or toxic particulates are attracted, the cleaning process and disposal must account for the hazardous nature of the particulates trapped. 
         [0003]    Note that none of these known filtration solutions are able to detect a sudden entrainment of particulate agents, nor are they able shut down and isolate the contaminated HVAC circuit, nor can they notify the proper building personal. Any effective solution must immediately detect the presence of particulate agents, immediately shut down the affected HVAC circuit, isolate that system, and notify the proper facilities management. 
       SUMMARY OF THE INVENTION 
       [0004]    With the aforementioned problems in mind, it is one purpose of the present invention to immediately detect unusual particulate agents entrained into the supply air of HVAC systems, shut down the supply air fan, isolate the contaminated HVAC circuit from the rest of the building, and decontaminate the HVAC circuit affected. Additionally, the apparatus and method of this invention permits the extent of the penetration of the particulate agents within the HVAC system to be measured. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0005]    Some of the purposes of the invention having been stated, others will appear as the description proceeds, when taken in connection with the accompanying drawings, in which: 
           [0006]      FIG. 1  is a schematic elevation view of a system embodying the present invention; and 
           [0007]      FIG. 2  is a schematic representation of a method of implementing the present invention. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0008]    While the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which a preferred embodiment of the present invention is shown, it is to be understood at the outset of the description which follows that persons of skill in the appropriate arts may modify the invention here described while still achieving the favorable results of the invention. Accordingly, the description which follows is to be understood as being a broad, teaching disclosure directed to persons of skill in the appropriate arts, and not as limiting upon the present invention. 
         [0009]    Areosolization devices have been demonstrated that are about the size of a 20 lb propane tank. HVAC supply air intake ducts typically have an open grill. The openings range from 3 feet to 10 feet in height. The grill (and possibly an additional coarse screen) would not hinder the entrance of biological agents or other harmful materials released from such a device either placed adjacent the supply air duct or within it should it be possible to easily remove the open grill. 
         [0010]    In accordance with the present invention, an HVAC system ( FIG. 1 ) supplying a structure  10  has an intake duct  11  with an air supply fan  12  drawing in air from the exterior of a conditioned area such as an office or other space. The fan  12  has a motor  14  and blades  15  bearing a sensor material  16  to detect significant changes in incoming supply air concentration of particulate matter. The sensor material  16  is also sometimes here referred to as a smart material due to its qualities and may be, for example only and not by way of limitation, applied films of piezoelectric materials, materials which form a capacitance or resistance couple, or materials which react with selected chemicals in such a way as to change electrical characteristics. Such materials may be applied in forms other than films, such as by depositing layers of materials by coating or the like. The material may be applied to surfaces other than the fan blades, although a recognized advantage of application to the blades is that rotation of the fan makes the sensor material self cleaning to a large degree. 
         [0011]    The sensor material  16  on the fan blades  15  is coupled to an appropriate controller  18 . The controller  18  is an electrical device with sufficient intelligence to monitor the change in electrical characteristics of the smart material  16 . The controller  18  preferably can be set or programmed to distinguish levels of response by the smart material and initiate or trigger appropriate action as described more fully hereinafter. The controller is also coupled to the fan motor  14  and to a duct closure mechanism  19  located a known distance downstream from the fan. A signal sent from the controller when a pre-calibrated particulate concentration threshold change occurs at the smart material and fan blades is capable of shutting down the supply air intake fan assembly quickly by coupling an output signal from the controller to the fan motor  14  and to a fan brake  20  to turn off the fan assembly and actuate the fan brake, stopping further capture and infiltration of the questioned particulate matter. 
         [0012]    The controller signals indicative of an inappropriate particulate material entering the HVAC system would also actuate the duct closure mechanisms  19 A,  19 B, thus sealing the contaminated portion of the HVAC duct work. The mechanisms  19 A,  19 B may be, for example only and not by way of limitation, shutters, an inflatable plug, or a swinging panel mounted in a normally withdrawn adjacent one side wall of the duct work. Measuring ports  21  located sequentially along the HVAC duct work downstream of the fan allow for sampling to determine the depth to which the potentially harmful particulates reached within the ductwork. This would allow an understanding of the extent of the HVAC ductwork that needed to be decontaminated. A secondary uncontaminated source of air  22  would then be released to slowly circulate in a countercurrent direction through the contaminated portion of the HVAC ductwork thoroughly mixing the release from a container  24  of a mist containing either biocidal chemicals to inactivate the biological agents or agglomerating agents to clump the particulates into non-respirable agglomerates (or both). The mist is collected via a chilling coil (or the like)  25  and the resulting condensate trapped into a holding vessel  26 . This process can be repeated with a sequence or regimen of treatments or simply repeated using a single treatment. 
         [0013]    Once the particulate contaminates have been collected into a holding vessel, the particulates can be further treated with heat, cold, ozonization, ultraviolet light, or chemical treatments to further render the condensate non-infectious and able to be disposed of safely. 
         [0014]    The controller  18  also signals to an appropriate annunciator to signal to facility operators that the sensor material  16  has detected the presence of an invasive particulate material. The annunciator may be a system of lights or audible alarms located wherever appropriate to attract the attention of supervisory personnel to the occurrence. 
         [0015]    These processes are illustrated by the flow chart of  FIG. 2 . In the chart, method steps are illustrated which comprise providing sensors for particulate material on the blades of an intake fan which impels a flow of air into the HVAC system of a structure; sensing with the sensors the presence of potentially harmful particulate material in an air flow impelled by the fan; and responding to the sensed presence of potentially harmful particulate material by stopping operation of the fan. The method steps, as illustrated, also comprise responding to the sensed presence of potentially harmful particulate material by stopping operation of the fan, blocking distribution of the impelled airflow downstream of the fan, trapping a contaminated portion of the impelled airflow; and decontaminating the trapped portion of the airflow. 
         [0016]    The preferred embodiments described here can be used in transportation environments (trains, planes, subways, etc), mail rooms, schools, hospitals, and command and control rooms that have vulnerable ventilation systems. 
         [0017]    In the drawings and specifications there has been set forth a preferred embodiment of the invention and, although specific terms are used, the description thus given uses terminology in a generic and descriptive sense only and not for purposes of limitation.