Abstract:
A fire safety system includes a sensor arrangement and control scheme for quickly sensing a fire, accurately identifying its location, and controlling a set of ceiling fans and overhead sprinklers to efficiently extinguish the fire. The fire safety system is particularly suited for large buildings such as warehouses, factories, gymnasiums, retail stores, auditoriums, convention centers, theaters or other buildings with large open areas. In some examples, the overhead fans are disabled prior to activating the sprinklers. The placement of the fire sensors, in some cases, are selected upon first considering the location of the overhead fans.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    This disclosure relates generally to a fire safety systems for buildings with overhead fans, and more specifically, to a system that disables a fan in response to a fire. 
       BACKGROUND 
       [0002]    Ceiling mounted fans are often used for circulating air within large buildings such as warehouses, factories, gymnasiums, retail stores, auditoriums, convention centers, theaters, or other buildings with large open areas. For fire safety, a matrix of overhead sprinklers are usually installed to quench any fires that might occur within the building. 
         [0003]    To detect a fire and control the operation of the fans and sprinklers appropriately, various types of fire sensors are available. They usually operate by optical detection (photoelectric), chemical reaction (ionization), or heat detection (fusible link or infrared sensor for radiation). 
         [0004]    Some optical photoelectric smoke detectors comprise an infrared light beam passing at a right angle in front of a photodiode or other photoelectric light sensor. In the absence of smoke, the light beam passes undetected in front of the light sensor. Smoke particles, however, can scatter the light beam into the sensor and trigger the smoke detector. 
         [0005]    In other types of optical photoelectric smoke detectors, known as projected beam detectors, an emitter projects a light beam across a room where a distant light receiver senses the intensity of the beam. When smoke disperses the beam, the receiver provides an alarm signal in response to sensing reduced light. 
         [0006]    Ionization style smoke detectors emit alpha radiation to create a small electrically conductive ionized path between two electrodes. When smoke absorbs the alpha particles, the smoke disturbs the ionized path and interrupts the current between the electrodes, thereby triggering the detector. 
         [0007]    Some fire detectors (e.g., heat detectors) are in the form of a fusible link incorporated within a sprinkler head. The fusible link holds a valve of the sprinkler closed until sufficient heat from the fire melts or otherwise destroys the link, thereby activating the sprinkler. 
         [0008]    In many cases, the sprinklers are fed by a pressure vessel containing a limited supply of water that is at a pressure higher than that of the municipal water that fills the pressure vessel. This allows an individual sprinkler or a group of sprinklers in a single zone of a multi-zone system to rapidly and intensely focus high-pressure water at a localized area before the fire has time to spread. 
         [0009]    If the location of the fire is not accurately determined and, as a result, the wrong sprinklers are activated, this can waste the high-pressure water on an area that does not need it. Depleting the limited supply of high-pressure water in this manner might allow the fire to spread with only lower pressure water, if any, left to suppress it. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a schematic diagram of an example fire safety system. 
           [0011]      FIG. 2  is a schematic diagram of another example fire safety system. 
           [0012]      FIG. 3  is a schematic diagram of another example fire safety system. 
           [0013]      FIG. 4  is a schematic diagram of yet another example fire safety system. 
           [0014]      FIG. 5  is a flow chart representative of machine readable instructions that may be executed by any of the controllers of  FIGS. 1-4  to implement a method or apparatus described herein. 
           [0015]      FIG. 6  illustrates an example manner of implementing any of the controllers of  FIGS. 1-4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Certain examples are shown in the above-identified figures and described in detail below. In describing these examples, like or identical reference numbers are used to identify common or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic for clarity. 
         [0017]    A need exists for a fire safety system that can quickly sense a fire, accurately identify its location, and control a series of ceiling fans and overhead sprinklers to efficiently extinguish the fire.  FIG. 1  illustrates an example fire safety system  10  for a building that has one or more overhead fans  12  (e.g.,  12   a  and  12   b ) for air circulation and at least one of a plurality of sprinklers  14  (e.g.,  14   a ,  14   b  and  14   c ) for extinguishing a fire  16 . Any number of fans  12  (e.g., 1, 3, 4, 5, etc.) and any number of sprinklers  14  (e.g., 1, 2, 4, 5, etc.) may be used. The term, “fire” used herein refers to any burning event or state of combustion including, but not limited to, an open flame and flameless smoldering. In the event of fire  16 , the activation of sprinklers  14  and deactivation of fans  12  are controlled in response to one or more sensors that are able to sense or react to a characteristic associated with fire  16 . Examples of characteristics associated with fire include, but are not limited to, heat, smoke and light. 
         [0018]    Activation of a sprinkler means that a sprinkler valve opens or a “sprinkler turns on” to spray or otherwise discharge a fire-extinguishing fluid (e.g., water, or any other suitable substance). Deactivation of a fan means that a “fan turns off” (i.e., the fan blades decelerate and may stop rotating). Depending on the particular control scheme and type of sensors being used, sprinklers  14  in the vicinity of fire  16  can be selectively activated individually, in zone groups, or all of the sprinklers can be activated together. Likewise, the deactivation of fans  12  may be done selectively or as a group. 
         [0019]    Examples of sensors that can sense or react to a characteristic associated with fire  16  include, but are not limited to, optical detectors, ionization detectors, heat detectors and combinations thereof. Information on various types of sensors is provided herein under the section entitled, “Background.” 
         [0020]    In the illustrated example of  FIG. 1 , sensors  18  (sensors  18   a  and  18   b ) are smoke detectors (e.g., optical, ionization or any other suitable type of smoke detector) that are installed near the building&#39;s ceiling  20  where relatively warm smoke tends to collect during, for example, fire  16 . In some cases, sensors  18  are positioned in updrafts created by fans  12 . Sensor  18   a , for example, is positioned in an updraft  22  of fan  12   a  such that sensor  18   a  may quickly sense smoke  24  being drawn up by the rising current of air returning to fan  12   a . In response to detecting smoke  24  from fire  16 , sensors  18  provide signals  26  and/or  28 . Signals  26  and  28  can be conveyed (e.g., transmitted) to a common controller  30  (e.g., programmable logic controller, computer, processor logic circuit, electromagnetic relay circuit, etc.) that in turn provides output signals  32  and/or  34  to deactivate fans  12   a  and/or  12   b . Alternatively, signals  26  and/or  28  may be conveyed directly to control wiring (not shown) within fans  12   a  and/or  12   b  to selectively deactivate the fans  12   a  and  12   b  without the use of controller  30 . 
         [0021]    Still referring to the example of  FIG. 1 , sensors  36  (e.g.,  36   a ,  36   b  and  36   c ) are heat detectors such as, for example, conventional fusible links that upon sufficient exposure to heat from fire  16  melt to actuate sprinklers  14 , or any other suitable type of heat detectors (e.g., thermocouple heat detectors, electro-pneumatic heat detectors. Sensors  36  can be supported by or incorporated within sprinklers  14  in any disclosed manner. 
         [0022]    In the illustrated example of  FIG. 1 , the sprinklers  14  are fed by a common pipe  38  that is connected to a pressure vessel  40 . Alternatively, sprinklers  14  may be fed by individual pipes (not shown) that are each connected to pressure vessel  40 . Pressure vessel  40  contains a certain volume of fire-extinguishing fluid  42  (e.g., water, or any other suitable substance) that may be maintained at a relatively high pressure via, for example, an air compressor  44 . If one or more sprinklers  14  turn on, for example, due to their respective fusible link melting under the heat of fire  16 , those open sprinklers may spray the high-pressure fluid  42  onto fire  16 . After one or more sprinklers  14  discharge the certain volume of fluid  42  from pressure vessel  40 , the compressor  44  may be turned off while a pump  46  or other fluid supply (not shown) continues feeding sprinklers  14  with fluid albeit at an appreciably lower pressure and volume relative to the high-pressure fluid  42  from pressure vessel  40 . 
         [0023]    Should fire  16  occur near a floor  48  of the building or elsewhere, example fire safety system  10  may respond with the following sequence of events. Before sensors  18  or  36  detect fire  16 , fans  12  are running normally while sprinklers  14  are inactive. As smoke  24  rises from fire  16 , sensor  18   a  detects the smoke and deactivates fan  12   a  and fan  12   b . With all of the fans  12  or at least the ones nearest fire  16  being inactive, air currents diminish (e.g. decrease). This calm period allows fire safety system  10  to more accurately determine the location of fire  16 . With the fans  12   a  and/or  12   b  turned off, heat from fire  16  can rise in a more direct upward path. The rising heat thus is more likely to be detected by the sensor  36  that is closest to fire  16 . In this example, sensor  36   a  is first to detect the heat, so sensor  36   a  transmits a signals that turns on sprinkler  14   a  while the other sprinklers remain inactive. Sprinkler  14   a  can then spray the full high-pressure volume of fluid  42  directly onto fire  16  without the other sprinklers wasting fluid  42  on areas that do not need it. In the illustrated example, as fluid  42  flows through a supply line  50 , a flow detector  52  provides a signal  54  that triggers a fire alarm (not shown) and/or deactivates compressor  44 . 
         [0024]    In the illustrated example, although a time period with relatively calm air may elapse between the moment at which sensor  18   a  first detecting smoke and the time at which sprinkler  14   a  turns on, this period can be minimized by stopping fan  12   a  as quickly as possible in response to sensor  18   a  detecting smoke. To do this, fans  12  can each be provided with a mechanical and/or electrical brake  54  (e.g., a frictional and/or dynamic brake). In some example implementations, to prolong the life of brake  54 , the brake may only be activated when fan  12  is turned off in response to a fire (e.g., turned off in response to sensor  18 ); otherwise, fan  12  could be allowed to simply coast to a stop when deactivated under normal operating conditions. 
         [0025]    To sense the occurrence of fire  16  more quickly and determine its location more accurately, an example fire safety system  56  of  FIG. 2  includes sensors  58  that are installed closer to floor  48 . Sensors  58  are schematically illustrated to represent any detector capable of sensing a fire-related characteristic including, but not limited to, heat, smoke and light. Examples of sensors  58  include, but are not limited to, optical detectors, fusible links, ionization detectors, and combinations thereof. Upon sensing fire  16 , sensors  58  provide feedback signals  60  that can be used for deactivating fans  12  individually or as a group. Signals  60  can be conveyed to fans  12  via controller  30 , sensors  58  can be hardwired directly to fans  12 , or signals  60  can be conveyed to fans  12  via a wireless communication link (e.g. radio waves, infrared, etc.). Other than a difference in response time and accuracy of locating a fire, fire safety system  56  operates similar to fire safety system  10 . 
         [0026]    For even greater response to fire  16 , an example fire safety system  62  of  FIG. 3  uses signals  60   a  and  60   b  to activate sprinklers  70  individually or as a group. Instead of waiting until heat from fire  16  reaches the sensors  36  (e.g., the fusible link), as is the case with fire safety systems  10  and  56 , sprinklers  70  are activated by electric valves  72  that are responsive to signals  64 ,  66  and  68 . Signals  60   a  and  60   b  can be processed by a controller  30 ′ to determine which sprinklers  70  should be activated and which fans  12  should be turned off. Upon considering signals  60   a  and/or  60   b , controller  30 ′ provides signals  64 ,  66  and/or  68  to control sprinklers  70  and provides signals  32  and/or  34  to control fans  12 . The transmission of the various signals may be done through hardwiring or wireless communication. 
         [0027]    In cases where installing fire detectors near a floor is not feasible, an example fire safety system  74  of  FIG. 4  might be more practical. Fire safety system  74  includes overhead sensors  18   c  and  18   d  that respond to two predetermined limits of smoke concentration. When the smoke reaches a first lower limit, sensors  18   c  and/or  18   d  provide signals  26 ′ and/or  28 ′ to a controller  30 ″ to turn off one or more fans  12 . When the concentration of smoke reaches a second higher limit, sensor  18   c  and/or  18   d  sends a signal to turn on one or more sprinklers  70  to turn on. During the period between reaching the two limits, the air within the building is relatively calm (e.g., the fans are turned off), which allows smoke to collect in an area generally above fire  16 , thereby enabling system  74  to selectively actuate the correct sprinklers  70 . 
         [0028]    In some example implementations, recognizing two limits of smoke concentration can be accomplished by installing two sets of smoke detectors, wherein one set of smoke detectors is more sensitive than the other. The more sensitive smoke detectors may deactivate fans  12 , and the less sensitive smoke detectors may activate sprinklers  70 . It is also conceivable and well within the scope of the disclosure to provide a single smoke detector with logic that distinguishes multiple levels of smoke concentration. 
         [0029]    In operation, the fire safety systems of  FIGS. 1-4  can perform the following process illustrated in  FIG. 5 . The process of  FIG. 5  is representative of machine readable instructions which may be executed by any of the controllers  30 ,  30 ′,  30 ″.  FIG. 6  illustrates an example manner of implementing any of the controllers  30 ,  30 ′,  30 ″. However, other methods to implement the fire safety systems of  FIGS. 1-4  may additionally or alternatively be used. Further, in some example implementations, one or more portion(s) of the following process may be combined, rearranged, or deleted. 
         [0030]    The example process of  FIG. 5  begins when a sensor detects a condition that a fire may be present (block  510 ). When a fire is suspected (block  510 ), the controller  30 ,  30 ′,  30 ″ deactivates the fan(s) in the area of the suspected fire (block  512 ). 
         [0031]    The controller there reads the output(s) of the sensor(s) in the area of the suspected fire to determine if a fire exists (block  514 ). If no fire is detected, control return to block  510 . An alarm may be sounded to request a manual check for fire and/or re-setting the system. 
         [0032]    If a fire is detected (block  514 ), the controller determines the approximate location of the fire within the building based on the outputs of the sensor(s) (block  516 ). The controller  30 ,  30 ′,  30 ″ then actuates one or more sprinkler(s) corresponding to the approximate location (block  518 ). Control then return to block  510  to monitor for fire starting in any other area(s) of the building. 
         [0033]    The instructions represented by  FIG. 5  may be implemented by multiple threads operating in parallel. 
         [0034]      FIG. 6  is an example manner of implementing the controller  30 ,  30 ′,  30 ″.  FIG. 6  is a block diagram of an example processor system  610  that may be used to implement the apparatus and methods described herein. As shown in  FIG. 6 , the processor system  600  includes a processor  612  that is coupled to an interconnection bus  614 . The processor  612  may be any suitable processor, processing unit or microprocessor. Although not shown in  FIG. 6 , the system  610  may be a multi-processor system and, thus, may include one or more additional processors that are identical or similar to the processor  612  and that are communicatively coupled to the interconnection bus  614 . 
         [0035]    The processor  612  of  FIG. 6  is coupled to a chipset  618 , which includes a memory controller  620  and an input/output (I/O) controller  622 . As is well known, a chipset typically provides I/O and memory management functions as well as a plurality of general purpose and/or special purpose registers, timers, etc. that are accessible or used by one or more processors coupled to the chipset  618 . The memory controller  620  performs functions that enable the processor  612  (or processors if there are multiple processors) to access a system memory  624  and a mass storage memory  625 . 
         [0036]    The system memory  624  may include any desired type of volatile and/or non-volatile memory such as, for example, static random access memory (SRAM), dynamic random access memory (DRAM), flash memory, read-only memory (ROM), etc. The mass storage memory  625  may include any desired type of mass storage device including hard disk drives, optical drives, tape storage devices, etc. 
         [0037]    The I/O controller  622  performs functions that enable the processor  612  to communicate with peripheral input/output (I/O) devices  626  and  628  and a network interface  630  via an I/O bus  632 . The I/O devices  626  and  628  may be any desired type of I/O device such as, for example, a keyboard, a video display or monitor, a mouse, etc. The network interface  630  may be, for example, an Ethernet device, an asynchronous transfer mode (ATM) device, an 802.11 device, a DSL modem, a cable modem, a cellular modem, etc. that enables the processor system  610  to communicate with another processor system. 
         [0038]    While the memory controller  620  and the I/O controller  622  are depicted in  FIG. 6  as separate functional blocks within the chipset  618 , the functions performed by these blocks may be integrated within a single semiconductor circuit or may be implemented using two or more separate integrated circuits. 
         [0039]    At least some of the aforementioned examples include one or more features and/or benefits including, but not limited to, the following: 
         [0040]    In some examples, a fire sensor is installed near the floor or at least below both a sprinkler and a fan. 
         [0041]    In some examples, a fire safety system includes one fire sensor for disabling a fan and a second fire sensor for activating a sprinkler. 
         [0042]    In some examples, a fire safety system disables a fan before activating a sprinkler. 
         [0043]    In some examples, a fire safety system uses the time between disabling a fan and activating a sprinkler to help identify the location of a fire. 
         [0044]    In some examples, a fire safety system includes a fan associated with a smoke detector and a sprinkler associated with a heat detector (e.g., fusible link). 
         [0045]    In some examples, an overhead fan includes a brake for quickly stopping the fan in the event of a fire. 
         [0046]    In some examples, a fire safety system coordinates the operation of a fan, a sprinkler, and a pressure vessel containing a certain volume of pressurized fire-extinguishing fluid. 
         [0047]    In some examples, a fire sensor is positioned within the updraft of an overhead fan. 
         [0048]    In some examples, a fire safety system includes a sensor system (one sensor or a plurality of sensors) responsive to two limits of smoke concentration. 
         [0049]    Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.