Abstract:
An aspirated smoke detector includes a manifold coupled to a smoke sensing chamber of the smoke detector. The manifold couples ambient smoke from a plurality of locations to the smoke sensing chamber. A location of the origin of the smoke can be determined by associating a member of a plurality of a different type of smoke sensor with each of the locations. When smoke is detected in the sensing chamber, the members of the plurality can be interrogated to determine the location of the origin of the smoke in the sensing chamber.

Description:
FIELD 
     The application pertains to smoke detectors. More particularly, the application pertains to aspirated smoke detectors which receive smoke samples from a plurality of locations. 
     BACKGROUND 
     Some commercial installations for aspirated smoke detectors require a larger area of coverage than single channel products are capable of meeting. In order to cover a larger area, a multichannel smoke detector is needed. For cost purposes, it is desirable to only use one smoke sensing chamber. But, if air is being sampled from multiple pipes to the one chamber, the user still needs to know which pipe (channel) the smoke came from. This can be done mechanically via valves and actuators, but this is complex, slow, and expensive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is block diagram illustrating aspects of an embodiment hereof; 
         FIG. 1A  is a side view, partly in section illustrating other aspects of the embodiment of  FIG. 1 ; and 
         FIG. 2  is a flow diagram illustrating a method in accordance herewith. 
     
    
    
     DETAILED DESCRIPTION 
     While disclosed embodiments can take many different forms, specific embodiments hereof are shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles hereof, as well as the best mode of practicing same, and is not intended to limit the claims hereof to the specific embodiment illustrated. 
     In accordance herewith, electronic gas or smoke sensing, on a per channel basis, can be combined with a common smoke chamber which receives smoke from multiple, different locations. Multiple ambient condition sensors, such as gas or smoke sensors, can be coupled to a manifold that combines multiple ambient air inflow channels to a single out flow that enters the smoke sensing chamber. 
     The ambient condition sensors can be activated after smoke is detected by the sensing chamber in order to determine, electrically, which input is the source of the detected smoke. By way of example only, and not limitation, a metal oxide semiconductor gas sensor can be coupled to each of the inflow channels. Those of skill will understand that other types of gas or smoke sensors come within the spirit and scope hereof. For example, electro-chemical gas sensors, photoelectric smoke sensors or the like, all without limitation, could also be used. 
     Metal oxide gas sensors are cross sensitive to a variety of gases that are produced by a range of fire types and are not subject to false alarm due to dust. They can be activated after the smoke chamber detects smoke. As a result, less signal processing is needed and power consumption is reduced. 
     Metal oxide gas sensors are typically available in TO-type packaging that can be fitted into a hole in the sampling tube or manifold. For example, a four channel device would use one smoke sensing chamber and four MOS gas sensors fitted to a four-to-one manifold. 
       FIG. 1  illustrates an aspirated smoke detector  10  which monitors smoke conditions in a plurality of different Protected Spaced,  1 ,  2 ,  3  . . . n of a region R. The Spaces  1 ,  2 ,  3  . . . n are coupled to the detector  10  via a plurality of conduits, or pipes, C 1 , C 2 , C 3  . . . Cn. Each of the conduits or pipes Ci has an inflow port located in or adjacent to a respective one of the Spaces  1 ,  2 ,  3  . . . n. 
     Each of the conduits or pipes Ci is coupled to a respective inflow port  10   a, b, c . . . n  of the detector  10 . Each of the inflow ports  10   i  is coupled to a respective Stage  1  ambient condition sensor, such as a gas or smoke sensor Si. The particular details of the sensors Si are not a limitation hereof. Sensor Si can be continuously or intermittently energized without limitation. Each of the sensors Si is coupled by a respective pipe or conduit to a manifold  12 . 
     Manifold  12  combines each of the n inflow conduits, such as  12   a ,  12   b  . . .  12   n  to a single output flow conduit, or pipe  14  which is in turn coupled to an inflow port  16   a  of main sensing chamber  16 . Ambient air, which might be carrying smoke or gas of interest, flows from manifold  12 , via conduit  14  into chamber  16 , where a gas or smoke sensing process can be carried. That air exits chamber  16 , via outflow port  16   b  and an aspirator  18 . 
     Control circuits  20 , of the detector  10 , are coupled to each of the Stage  1  sensors Si via cables  16 - 1 , as well as to the main sensing chamber  16  by cables  16 - 2 . Control circuits  20  can implement gas and/or smoke processing as in exemplary method  100  discussed subsequently. Control circuits  20  could be implemented, at least in part, via a programmable processor  20   a  and local control software  20   b.    
     Control circuits  20  can communicate via a wired or wireless medium  22  with a displaced monitoring system control unit  24 . It will be understood that details of the control unit  24  are not limitations hereof. 
       FIG. 1A  illustrates a gas sensor Si coupled via cable  16 - i  to control circuits  20 . Sensor Si is attached to conduit  12   i  which has a diameter d1. Those of skill will understand that diameter d1 is selected in accordance with a height dimension d2 of sensor Si to provide an appropriate flow dimension d3 for the inflowing atmospheric air from the respective Protected Space i. 
       FIG. 2  illustrates a flow diagram of a method  100  of operating detector  10 . The system of detector  10  can be initialized as at  102 . It can be placed in a smoke detection mode, as at  104 . If smoke is detected in main sensing chamber  16 , as at  106 , outputs from all of the Stage  1  gas or smoke sensors Si are read as at  110 . If not on, they can be first turned on as at  108 . 
     Control circuits  20  can determine which of the sensors Si are detecting gas or smoke, as at  110 . The conduit or pipe, Ci through which the gas or smoke is flowing can then be identified. This in turn specifies the Protected Space i from which the gas, or smoke is being drawn. Circuits  20  can then emit an appropriate alarm indictor to the control unit  24 . 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims. 
     Further, logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. Other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from the described embodiments.