Abstract:
A system and method for fire suppression proactively identifies persons present, during a fire, in a fire suppressant release area. The persons are identified using an electronic monitoring system. An fire suppression system using a suppressant that is effective but unsafe for humans is put into service only if no person is detected. In situations where a person is present, an alternate fire suppressant is released that is safe for humans.

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to a fire suppression system and method, in particular, for controlling carbon dioxide (CO 2 ) based systems. 
     Various industrial sites, including, for example, power plants and manufacturing sites, are expected to run continuously with no unplanned shutdowns. Plants and equipment are typically built with the highest degree of safety in mind for protection against unexpected events. With respect to unforeseen fires, carbon dioxide-based fire suppressant constitutes a major fire extinguishing medium, apart from water hydrant and water sprinkler systems. A container that discharges carbon dioxide forms a quick blanket around the fire and thereby helps in fire extinction. Carbon dioxide-based fire protection systems can potentially pose a life threatening situation for workers in the release area if they fail to evacuate in time. Previous measures designed to address this risk include manual mechanical shut off methods to prevent carbon dioxide release, and alarms or loudspeaker announcements advising evacuation prior to the release. 
     The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. 
     BRIEF DESCRIPTION OF THE INVENTION 
     A system and method for fire suppression proactively identifies persons present, during a fire, in a fire suppressant release area. The persons are identified using an electronic monitoring system. An fire suppression system using a suppressant that is effective but unsafe for humans is put into service only if no person is detected. In situations where a person is present, an alternate fire suppressant is released that is safe for humans. 
     In one embodiment, a fire suppression system comprises a processing system and a fire detector that are electrically connected. A person detector is also electrically connected to the processing system and detects people in a monitored area. A first container system comprises an unsafe fire suppressant, and a second container system comprises a safe fire suppressant. Both container systems are electrically connected to the processing system. 
     In another embodiment, a fire suppression system comprises a processing system and a fire detector electrically connected to the processing system for sending a fire signal to the processing system in response to detecting a fire. A database that is accessible by the processing system stores a list of persons entering and exiting a monitored area. A first container system comprises a carbon dioxide-based fire suppressant, and a second container system comprises a human-safe fire suppressant. Both containers are electrically connected to the processing system for releasing their fire suppressant in response to receiving a signal from the processing system. 
     In another embodiment, a method of fire suppression comprises automatically detecting a fire within a monitored area, automatically checking for a presence of one or more humans in the monitored area, and automatically releasing a carbon dioxide-based fire suppressant into the monitored area if there are no humans present there. 
     This brief description of the invention is intended only to provide a brief overview of subject matter disclosed herein according to one or more illustrative embodiments, and does not serve as a guide to interpreting the claims or to define or limit the scope of the invention, which is defined only by the appended claims. This brief description is provided to introduce an illustrative selection of concepts in a simplified form that are further described below in the detailed description. This brief description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which: 
         FIG. 1  is a schematic diagram of a fire suppression system used for monitoring an area; and 
         FIG. 2  is a flow chart of a method for operating the fire suppression system of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With respect to  FIG. 1  there is illustrated one embodiment of a fire suppression system  100  comprising an electronic system having electric circuits for detecting, identifying, and recording the presence of persons  112  within a monitored area  113 . Fire suppression system  100  includes a fire detector  105 , electronic ID readers or detectors  103 ,  104 , RFID detector  110 , an audible and visible alarm  119 , fire suppressant containers  108 ,  109 , fire suppressant tank outlets  116 ,  117 , all electrically connected to fire control processing system  106  over communication channel  107 . A person  111  not within monitored area  113  enters monitored area  113  through entry/exit points  101 ,  102 . Similarly, a person  112  within monitored area  113  exits monitored area  113  through entry/exit points  101 ,  102 . Fire suppressant tanks  114 ,  115  for flooding monitored area  113  are connected to fire suppressant tank outlets  116 ,  117 , respectively, via pipes  118 . 
     Electronic ID readers or detectors  103 ,  104  may be deployed at each entry/exit point  101 ,  102  for detecting entry and exit by persons into and out of monitored area  113 . Such devices may comprise employee badge readers, which can be card-based magnetic strip reading devices or bar code reading devices; text input devices such as keypads or other input devices for inputting ID numbers or names; radio frequency identification (RFID) reading devices which comprise circuitry for detecting an RFID source worn or carried by an employee, worker or other person; a facial imaging and recognition device which includes a digital camera for capturing an image of a person&#39;s face and facial recognition programming for identifying the person based on the captured facial image; a retinal imaging and recognition device which captures an image of a portion of a person&#39;s eye for identifying the person based on retinal patterns; a voice recognition device for receiving a voice sample from a person in order to identify the person based on voice characteristics; a fingerprint reader; a hand print reader; or any combination thereof. The ID readers or detectors  103 ,  104  are placed at each entry/exit point  101 ,  102  and contain electric circuits for detecting and reading ID information from each person entering and exiting monitored area  113 . The ID information so detected is electronically stored in electronic memory of fire control processing system  106  or in memory that is accessible by fire control processing system  106 . 
     Instead of, or in combination with, the readers and detectors just described, an RFID detection system may be deployed within monitored area  113  to track personnel that are present within monitored area  113  by detecting RFID devices worn or carried by personnel within monitored area  113 . Persons entering within range of RFID detector  110  are detected, identified, and recorded as being present in monitored area  113 . Conversely, persons that depart monitored area  113  are detected, identified, and recorded as being no longer present in range of RFID detector  110  in monitored area  113 . Such detection systems, as described herein, can be used to store the detected identification data and used in conjunction with, for example, an employee database that may be part of a standard security system employed by a company for controlling entry to monitored areas  113  of work sites by authorized personnel. The fire control processing system  106  may be configured to have access to such a security system database. Each electronic ID reader or detector  103 ,  104 , or the personnel ID data generated thereby, is accessible by fire control processing system  106  for determining, at any time, the presence of persons within monitored area  113 . 
     Fire control processing system  106  can be configured to be connected to, or part of, such a standard security system for tracking personnel that enter and exit monitored area  113 . Databases utilized for tracking such personnel can be electrically connected to fire control processing system  106  such that fire control processing system  106  can freely access such data to determine whether there are persons who have entered but not exited the monitored area  113  via the entry/exit points  101 ,  102 . In the embodiment shown in  FIG. 1 , the fire control processing system  106  directly manages and is directly connected to the electronic ID readers and detectors  103 ,  104  using communication channel  107 . In the embodiment shown in  FIG. 1 , fire control processing system  106  comprises a processor and memory for managing personnel ID data and for storing and executing programs according to the algorithms described herein. 
     The fire control processing system  106  can be located proximate to or remote from monitored area  113 . Communication channel  107  represents either a wired communication channel  107  or a wireless communication channel. Wired communication channel  107  can be implemented as a networked communication channel, such as an Ethernet or USB communication channel, or a privately designed communication channel. Similarly, the communication channel implemented as a wireless communication channel can be implemented as a WiFi, cellular, or a privately designed wireless communication channel. Fire control processing system  106  may comprise a microcontroller, memory, and electric circuits for executing a stored computer program triggered by reception of the fire condition signal from fire detector  105 . Fire control processing system  106  may be embodied in an application executed on a general purpose processing system such as a PC or laptop, a site wide server, or a network-based system remotely located from monitored area  113  and communicating, over communication channel  107  implemented as an internet connection, with fire detector  105  or other detection devices proximate to monitored area  113 . In one embodiment, communication channel  107  may comprise, in various combinations, an internet connection, a cellular network connection, a wired network connection and a WiFi connection interoperating to maintain communication between detection devices proximate to monitored area  113  and fire control processing system  106  connected remotely to such devices. 
     In one embodiment, electronic ID readers and detectors  103 ,  104  are not configured to identify each person entering and exiting monitored area  113 . Rather, the electronic ID readers and detectors  103 ,  104  track persons who enter and exit monitored area  113  without identifying such persons and merely keep track of a total count of persons entering and exiting monitored area  113 . Such devices can comprise one or more of the readers and detectors described above and can further include other means for tracking entry and exit of persons from monitored area  113 , such as turnstiles, infrared detectors, and light beam detectors, for example. An RFID detection system using RFID detector  110  can anonymously detect persons carrying or wearing generic RFID tags. RFID detector  110  can be replaced or used together with a motion detector or infrared detector for determining that one or more persons are present or not present within monitored area  113 . Any such detection devices communicate detection data to fire control processing system  106  as described above to indicate whether detection data indicates the presence of one or more persons within monitored area  113 . Detected motion by a motion detector, or a total entry count higher than an exit count at entry/exit points  101 ,  102  are further examples of data indicating the presence of persons in monitored area  113 . 
     The fire suppressant container  109  is designated to store a human-safe fire suppressant, and container  108  is designated to store a carbon dioxide-based fire suppressant, wherein each container is connected to fire control processing system  106  using communication channel  107 . Each of fire suppressant containers  108 ,  109  comprise an electrically actuable valve for releasing its contents under pressure upon receiving an electric signal from fire control processing system  106  over communication channel  107  to open its valve. Similarly, the valves in fire suppressant containers  108 ,  109  close in response to receiving a second electric signal from fire control processing system  106  over communication channel  107  for terminating release of fire suppressant. The fire suppression system  100  is automated and is programmed to constantly monitor an area  113  such as a region on a factory floor, or other commercial or private premises wherein various personnel may enter and exit via one or more entry/exit points  101 ,  102 . The premises may be occupied by at least one person intermittently, during scheduled times, or at all times. A programmed operation of fire suppression system  100  is triggered upon receiving a signal at fire control processing system  106  from fire detector  105  that a fire condition has been detected, as described below. 
     In one embodiment, one or more fire detectors such as fire detector  105  is powered via battery power or permanent site power supply, and constantly monitors area  113 . Upon detecting a fire condition, fire detector  105  issues an electric signal to fire control processing system  106  over communication channel  107 . Fire detector  105  may comprise any conventional fire detection means such as a smoke detector or a heat detector. In one embodiment, a smoke detector may comprise a photodetector that monitors clarity of the air within smoke detector and is triggered when fire generated smoke particles affect transmissivity of the air within the detector above or below a preset threshold. In another embodiment, a smoke detector may comprise a ionization detector that monitors the air within the smoke detector and is triggered when fire generated smoke particles affect conductivity of ionized air within the smoke detector above a certain preset threshold. The fire detector  105  may also comprise a combination of the above types of smoke detectors. In another embodiment, fire detector  105  may be a heat detector, such as a temperature reading electronic heat detector, or an eutectic alloy (melting switch) heat detector, or a rate-of-rise heat detector, or a combination of the above. In one embodiment, the fire detection mechanism may be powered by connecting it to a permanent building power supply (mains), a battery, or capacitor-based power supply, or in any combination thereof, and using any combination thereof as a backup power supply. The preceding examples of fire detection mechanisms are not to be interpreted in a limiting sense, and are described herein as exemplary detection mechanisms useable with embodiments of the present invention. Any other type of fire detection device used in fire suppression system  100  is contemplated as an embodiment of the present invention. 
     The human-safe fire suppressant in fire suppressant container  109  may include a Dry Chemical Powder (DCP) fire extinguishing agent, or another fire suppressant that is safe for humans, to be used when one or more persons are detected inside monitored area  113  during a fire condition. Fire suppressant container  109  using a DCP fire suppressant is available in portable cylinders pressurized with nitrogen. Similarly, fire suppressant container  108  using a carbon dioxide-based fire suppressant is available in portable pressurized cylinders. In one embodiment, large fire suppressant tanks  114 ,  115  are connected with piping system  118  to fire suppressant tank outlets  116 ,  117  respectively. The outlets are capable of selectively flooding monitored area  113  under control of an electric signal from fire control processing system  106  over communication channel  107  to either or both of fire suppressant tank outlets  116 ,  117 . In this embodiment, fire suppressant tank  114  comprises a carbon dioxide-based fire suppressant in sufficient quantities for flooding monitored area  113 , while fire suppressant tank  115  comprises a fire suppressant safe for humans in sufficient quantities for flooding monitored area  113 , such as the DCP described above. Both fire suppressant tank outlets  116 ,  117  comprise valves selectively electrically actuable, individually or together, under control from an electric signal received from fire control processing system  106  over communication channel  107  to open and release fire suppressant from the fire suppressant tanks  114 ,  115 , respectively, through a corresponding pipe  118  and through fire suppressant tank outlets  116 ,  117  for flooding monitored area  113 . Similarly, the valves in fire suppressant tank outlets  116 ,  117  are selectively electrically actuable to close, for terminating the release of fire suppressant into monitored area  113  upon receiving a second signal from fire control processing system  106 . 
     The DCP in fire suppressant container  109  and in fire suppressant tank  115  may comprise monoammonium phosphate. Monoammonium phosphate is a well-known fire suppressant and is non-toxic to human beings. In the event that carbon dioxide has been released, or carbon dioxide is otherwise present, and a person is in, or enters, the monitored area  113  during a fire condition state, the DCP from fire suppressant container  109  or from fire suppressant tank  115  may be released into monitored area  113  as described below. 
     With reference to  FIG. 2 , there is illustrated a fire control processing system algorithm  200  performed by fire control processing system  106  according to a program stored in a memory of fire control processing system  106 . As described above, fire detector  105  constantly monitors area  113  for a fire condition. When fire detector  105  detects a fire condition, it transmits an electric signal over communication channel  107  to fire control processing system  106  which interprets the signal as a fire condition detected signal at step  201 . At step  202 , fire control processing system  106  triggers an audible and visible alarm  119  in monitored area  113  by sending an electrical signal to alarm  119  over communication channel  107 . At step  203 , fire control processing system  106  determines if one or more people are present in monitored area  113  as described above. For example, fire control processing system can access an ID information database to determine that people who have entered monitored area  113  have not yet exited, that a total entry count is less than a total exit count, that RFID detector  110  is currently detecting RFID tags in monitored area  113 , or that a motion detector is currently detecting motion in monitored area  113 . 
     If fire control processing system  106  determines that one or more people are present in monitored area  113 , then at step  204  fire control processing system  106  sends an electric signal over communication channel  107  to human-safe fire suppressant container  109 , or to human-safe fire suppressant tank outlet  117 , or both, which causes corresponding valves to open and release human-safe fire suppressant from container  109  into monitored area  113 , and/or from tank  115  through fire suppressant tank outlet  117  for flooding monitored area  113 . A programmed delay occurs at step  205  for a preselected duration to allow time for people present in monitored area  113  to evacuate. At step  206 , fire control processing system  106  checks to determines if people are present in monitored area  113 . If fire control processing system  106  determines that people are still present in monitored area  113  then the human-safe fire suppressant continues to be released at step  204  until it is depleted, manually shut off, or the fire control processing system no longer detects a fire condition. 
     If fire control processing system  106  determines at step  206  that people are no longer present in monitored area  113 , then the fire control processing system  106  sends an electric signal over communication channel  107  to carbon dioxide-based fire suppressant container  108 , or to carbon dioxide-based fire suppressant tank outlet  116 , or both, which causes the corresponding valves to open and release carbon dioxide-based fire suppressant from container  108  into monitored area  113 , and/or from fire suppressant tank  114  for flooding monitored area  113  through fire suppressant tank outlet  116 . The release of carbon dioxide-based fire suppressant at step  207 , following decision step  206 , may include fire control processing system  106  sending a second electric signal over communication channel  107  to fire suppressant container  109 , or to fire suppressant tank outlet  117 , or both, to close their valves and terminate release of the human-safe fire suppressant, or the human-safe fire suppressant can continue to be released together with the carbon dioxide-based fire suppressant. After step  207 , at step  206 , fire control processing system  106  determines if people are present in monitored area  113 . If fire control processing system  106  determines that people are still no longer present in monitored area  113  then the carbon dioxide-based fire suppressant continues to be released at step  207  until it is depleted, manually shut off, the fire control processing system no longer detects a fire condition, or until fire control processing system  106  detects that people are present at step  206 . 
     If fire control processing system  106  determines at step  206  that people are present in monitored area  113  after a release of carbon dioxide-based fire suppressant at step  207 , then, at step  208  the fire control processing system  106  sends a second electric signal over communication channel  107  to carbon dioxide-based fire suppressant container  108 , or to carbon dioxide-based fire suppressant tank outlet  116 , or both, which causes the corresponding valves to close and terminate release of the carbon dioxide-based fire suppressant from container  108  and/or from fire suppressant tank  114  into monitored area  113 . At step  204 , if the human-safe fire suppressant container  109  and/or fire suppressant tank outlet  117  was not closed, the human-safe fire suppressant continues to be released until it is depleted, manually shut off, or the fire control processing system no longer detects a fire condition. If the human-safe fire suppressant container  109  and fire suppressant tank outlet  117  were closed, then fire control processing system  106  again sends an electric signal over communication channel  107  to human-safe fire suppressant container  109 , or to human-safe fire suppressant tank outlet  117 , or both, which causes corresponding valves to open and again release human-safe fire suppressant from container  109  into monitored area  113 , and/or from tank  115  through fire suppressant tank outlet  117  for flooding monitored area  113 . The fire control processing system algorithm  200  then continues through to step  206  as described above. 
     Returning back to step  203 , if, after receiving a fire condition detected signal at step  201  and triggering the alarm at step  202 , fire control processing system  106  determines that no people are present in monitored area  113 , then at step  207  the fire control processing system  106  sends an electric signal over communication channel  107  to carbon dioxide-based fire suppressant container  108 , or to carbon dioxide-based fire suppressant tank outlet  116 , or both, which causes the corresponding valves to open and release carbon dioxide-based fire suppressant from container  108  into monitored area  113 , and/or from fire suppressant tank  114  for flooding monitored area  113  through fire suppressant tank outlet  116 . In one embodiment, the release of carbon dioxide-based fire suppressant at step  207  may include fire control processing system  106  also sending an electric signal over communication channel  107  to fire suppressant container  109 , or to fire suppressant tank outlet  117 , or both, to simultaneously release the human-safe fire suppressant into monitored area  113  together with the carbon dioxide-based fire suppressant. After step  207 , at step  206 , fire control processing system  106  determines if people are present in monitored area  113 , and the algorithm continues as described above. 
     In view of the foregoing, embodiments of the invention provide an automatic fire suppressant release system designed to protect people in the vicinity of the fire from hazardous fire suppressants. A technical effect is to automate the fire suppressant system without requiring manual mechanical shut off of fire suppressants that are hazardous to people. 
     As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, method, or computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.), or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “service,” “circuit,” “circuitry,” “module,” and/or “system.” Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon. 
     Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
     Program code and/or executable instructions embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing. 
     Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user&#39;s computer (device), partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). 
     Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks. 
     The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.