Description
SYSTEM FOR EXTINGUISHING FIRE OF TRAIN
Technical Field
[1] The present invention relates generally to a system for automatically extinguishing a train fire and, more particularly, to a system for automatically extinguishing a train fire, which, when a fire occurs in a train car, can automatically and rapidly extinguish the train fire, easily manage the histories of fire extinguishers, and monitor the status of the train fire. Background Art
[2] In the past, when a fire occurs in a train car, passengers passively sense the fire and then evacuate, or the fire is automatically detected and passengers are evacuated using alert broadcasting, so as to prevent the loss of lives caused by flames, heat, smoke or poisonous gas.
[3] However, in the past, there is a problem in that, in the case of a fire, an engineer is not aware of the occurrence of a fire, continues to drive a train and, thus, causes the loss of lives although the engineer should stop the train and let passengers evacuate to a safe place.
[4] Furthermore, since which train car is on fire cannot be determined, it is difficult to rapidly evacuate passengers to other safe train cars. Moreover, there is another problem in that passengers erroneously move to a train car in which a fire is occurring while evacuating, due to confusion, thus increasing the loss of lives.
[5] Furthermore, whether fire extinguishers to operate in the case of a fire have failed is manually checked, so that there is inconvenience. Moreover, there is a problem in that the fire extinguishers are not appropriately operated in the case of a fire because the failure thereof was not previously detected.
[6] Furthermore, after the operation of a fire extinguisher, it is difficult to know which fire extinguisher was operated, so that the histories of fire extinguishers are not ef¬ ficiently managed. Moreover, there is a problem in that a station building at which a train in which a fire is occurring will arrive is not aware of the occurrence of the fire and, thus, cannot take countermeasures against the fire. Disclosure of Invention
Technical Problem
[7] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a system for automatically extinguishing a train fire, which is capable of precisely de¬ termining the train car in which a fire is occurring, and safely evacuating passengers
and rapidly extinguishing the fire at the same time.
[8] Another object of the present invention is to provide a system for automatically ex¬ tinguishing a train fire, which is capable of easily determining the time for the repair or replacement of the fire extinguishing agent discharging unit of each train car by auto¬ matically determining the status of the fire extinguishing agent discharging unit.
[9] Furthermore, still another object of the present invention is to provide a system for automatically extinguishing a train fire, which is capable of rapidly taking coun- termeasures by monitoring the status of a train car in which a fire is occurring in real time, and minimizing damage in an emergency situation by employing a fire ex¬ tinguishing agent that is harmless to the human body and effective in extinguishing fires.
Technical Solution
[10] A system for automatically extinguishing a train fire in accordance with a preferred embodiment of the present invention includes fire detection units provided in train cars of a train and configured to detect the occurrence of a fire; a control unit for receiving a signal from the fire detection unit and determining whether a fire is occurring; nozzle units provided in the train cars and configured to spray a fire extinguishing agent when the control unit determines that a fire is occurring; and fire extinguishing agent discharging units comprising housings that communicate with the nozzle units and are filled with the fire extinguishing agent at a predetermined pressure, valves for se¬ lectively opening and closing the housings and the nozzle units, and actuators for operating the valves under the control of the control unit.
[11] In accordance with a preferred embodiment, the fire detection units are assigned fire detection IDentification (ID) numbers that match the train car numbers of the train cars. The fire extinguishing agent discharging units are assigned ID numbers that match the fire detection ID numbers.
[12] In that case, the control unit determines the fire detection ID number of a fire detection unit that transmits a fire signal. The control unit operates the actuator of a fire extinguishing agent discharging unit that matches the fire detection ID number.
[13] Furthermore, each of the fire extinguishing agent discharging units comprises a filling pressure sensor unit for detecting filling pressure of the fire extinguishing agent. Preferably, the control unit determines a fire detection ID number that matches a discharge ID number of a fire extinguishing agent discharging unit in which the filling pressure is below a predetermined pressure, and determines a train car number that matches the fire detection ID number.
[14] Furthermore, the system of the present invention further includes camera units provided in the train cars of the train and assigned camera ID numbers that match the
fire detection ID numbers. The control unit determines a fire detection ID number of a fire detection unit that transmits a fire signal. Furthermore, the control unit captures an image by operating a camera unit having a camera ID number that matches the fire detection ID number.
[15] Meanwhile, in accordance with another preferred embodiment, the fire detection units are assigned fire detection ID numbers that match the train car numbers of the train cars. The fire extinguishing agent discharging units are assigned discharge ID numbers that match the train car numbers of the train cars.
[16] In that case, the control unit determines a train car number that matches the fire detection ID number of a fire detection unit that transmits a fire signal. Furthermore, the control unit preferably operates the actuator of a fire extinguishing agent discharging unit having a discharge ID number that matches the train car number.
[17] Furthermore, each of the fire extinguishing agent discharging units comprises a filling pressure sensor unit for detecting filling pressure of the fire extinguishing agent. The control unit determines a fire detection ID number that matches a discharge ID number of a fire extinguishing agent discharging unit in which the filling pressure is b elow a predetermined pressure. Furthermore, the control unit preferably determines a train car number that matches the fire detection ID number.
[18] Furthermore, the system of the present invention further includes camera units provided in the train cars of the train and assigned camera ID numbers that match the fire detection ID numbers. The control unit determines a train car number that matches the fire detection ID number of a fire detection unit that transmits a fire signal. Furthermore, the control unit captures an image by operating a camera unit having a camera ID number that matches the train car number.
[19] Meanwhile, the system of the present invention further includes communication terminals that are provided in the train cars and are configured to communicate with the engineer's room of the train or a station building, and an auxiliary power supply unit that supplies auxiliary power to the actuators, the valves, the filling pressure sensors, the control unit and the fire detection units when power supply from a pantograph of the train is cut off.
[20] Furthermore, the fire extinguishing agent is preferably a flouoroketone.
Advantageous Effects
[21] In accordance with the present invention described above, there is an effect in that a fire can be automatically and rapidly extinguished in the case where the fire is occurring in a train car.
[22] Furthermore, which train car is on fire is immediately determined, and coun- termeasures can be rapidly taken. Moreover, fire extinguishing work can be performed
only in a corresponding train car in which a fire is occurring, so that a fire can be ef¬ fectively dealt with.
[23] Furthermore, which fire extinguishing agent discharging unit has no fire ex¬ tinguishing agent can be determined. Moreover, the time for the repair or replacement of a fire extinguishing agent discharging unit filled with an extinguishing agent can be automatically and easily determined by detecting a filling pressure at which the fire ex¬ tinguishing agent discharging unit is filled with the fire extinguishing agent.
[24] Furthermore, countermeasures can be rapidly taken by monitoring the status of a train car in which a fire is occurring in real time.
[25] Furthermore, even if an emergency situation in which power cannot be supplied occurs, the system can be stably operated, so that a fire can be rapidly extinguished. Brief Description of the Drawings
[26] FIG. 1 is a block diagram schematically illustrating a system for automatically ex¬ tinguishing a train fire in accordance with a preferred embodiment of the present invention;
[27] FIGS. 2 and 3 are diagrams illustrating the implementation of the automatic train fire extinguishing system of FIG. 1 in a train;
[28] FIGS. 4 to 7 are diagrams illustrating the relationships between the previously stored train car number of train cars, the ID numbers of fire detection units, the ID numbers of fire extinguishing agent discharging units and the ID numbers of camera units;
[29] FIG. 8 is a diagram illustrating a method of automatically extinguishing a train fire in accordance with a first embodiment of the present invention;
[30] FIG. 9 is a diagram illustrating a method of automatically extinguishing a train fire in accordance with a second embodiment of the present invention; and
[31] FIG. 10 is a diagram illustrating a method of determining whether a fire ex¬ tinguishing agent discharging unit has failed, which is applied to the embodiments shown in HGS. 8 and 9. Best Mode for Carrying Out the Invention
[32] A system for automatically extinguishing a train fire in accordance with a preferred embodiment of the present invention is described below with reference to FIGS. 1 to 3.
[33] The automatic train fire extinguishing system according to the preferred embodiment of the present invention includes a fire detection unit 120, a control unit 110, a nozzle unit 140 and a fire extinguishing agent discharging unit 130.
[34] The fire detection unit 120 includes a plurality of fire detection units for respective train cars 121, 122, ..., and detects the occurrence of a train fire. The fire detection unit 120 can detect whether a train fire is occurring through the detection of smoke, heat or
flames that is/are produced in the case of a fire.
[35] A method of detecting smoke is performed in such a way as to determine whether a fire is occurring through the reception of light, which is emitted from a light emitting unit, using a light receiving unit. The method of detecting smoke determines that a fire is occurring using the control unit 110 if the amount of received light is smaller than a predetermined value, based on the principle that the amount of light received by the light receiving unit decreases due to smoke when the smoke is produced in the case of a fire.
[36] Furthermore, a method of detecting heat measures heat generated in the case of a fire using a temperature sensor, and determines that a fire is occurring using the control unit 110 if the measured temperature is higher than a predetermined temperature.
[37] Furthermore, a method of detecting flames determines that a fire is occurring if variation in ultraviolet ray or infrared ray, which is radiated from flames at the time of fire, is higher than a predetermined amount.
[38] The control unit 110 determines whether a fire is occurring using a signal detected by the fire detection unit 120, and controls the fire detection unit 120 and the fire ex¬ tinguishing agent discharging unit 130.
[39] The nozzle unit 140 includes a plurality of nozzles 141, 142, .... When the control unit 110 determines that a fire is occurring, a fire extinguishing agent discharged from the fire extinguishing agent discharging unit 130 is finally discharged through the nozzle unit 140, so that it is preferred that the nozzles 141, 142, ... be located in the ceilings of train cars.
[40] The fire extinguishing agent discharging unit 130 includes a plurality of fire ex¬ tinguishing agent discharging unit 131, 132, ... in respective train cars. The fire ex¬ tinguishing agent discharging unit 130 includes housings 13 Id, 132d, ... having filling units (not shown) that are filled with a fire extinguishing agent under a predetermined filling pressure, valves 131b, 132b, ... for selectively opening and closing flow paths between the filling unit and the nozzle unit 140, and actuators 131a, 132b, ... for activating the opening and closing of the valves 131b, 132b, ....
[41] In that case, the fire extinguishing agent discharging unit 130 is located in the ceiling of a train, as shown in FIG. 2. Alternatively, the fire extinguishing agent discharging unit 130 may be in the bottom of the train for ease of installation or dis¬ placement thereof, as shown in FIG. 3.
[42] Accordingly, in the case where it is determined that a fire is occurring, the actuators
131a, 132a, ... are operated by the control unit 110 and, therefore, the valves 131b, 132b, ... are opened. Thereafter, the fire extinguishing agent charged in the filling unit is finally discharged by the filling pressure through the nozzle unit 140 to the outside, thereby extinguishing a fire.
[43] In that case, it is preferable to determine the train car in which a fire is occurring and conduct fire extinguishing work only in the train car in which the fire is occurring.
[44] In accordance with a first preferred embodiment of the present invention, fire detection units 120 located in respective train cars are assigned fire detection ID numbers that match the train car numbers of the train cars, respectively. Furthermore, the fire extinguishing agent discharging units 130 are assigned discharge ID numbers that match the fire detection ID numbers, respectively.
[45] As illustrated in FIGS. 4 and 6, respective train cars are assigned, for example, train car numbers A to J. Furthermore, the fire detection units 120 installed in respective train cars are assigned fire detection ID numbers a to j. Furthermore, the fire ex¬ tinguishing agent discharging units 130 installed in respective train cars are assigned discharge ID numbers al to jl, respectively.
[46] Accordingly, when a fire is detected by the fire detection unit 122 that is assigned a fire detection ID number b, the fire detection unit 122 transmits a related signal to the control unit 110. The control unit 110 can determine which train car is currently on fire by determining which train car has a train car number B that matches a fire detection ID number b.
[47] Furthermore, the control unit 110 causes fire extinguishing work to be performed only in a corresponding train car by determining a discharge ID number bl that matches the fire detection ID number b and activating only the actuator 132a of the fire extinguishing agent discharging unit 132a that corresponds to the discharge ID number bl.
[48] With that, which train car is on fire can be immediately detected and coun- termeasures can be rapidly taken. Furthermore, since fire extinguishing work is performed in a corresponding train car in which a fire is occurring, a fire can be ef¬ fectively dealt with. Moreover, since which of the fire extinguishing agent discharging units 130 has no fire extinguishing agent can be determined, the time for the re¬ placement of a housing 132d that is filled with a fire extinguishing agent can be easily determined.
[49] Furthermore, it is preferred that camera units 150, which are assigned camera ID numbers a2 to j2 that match the fire detection ID numbers, be provided in respective train cars. The control unit 110 captures the image of the interior of a train car on fire by operating a camera unit 152 having a camera ID number b2 that matches a fire detection ID number b, and transmits the image to an engineer's room or a station building 175 through a data transceiver unit 180.
[50] Furthermore, it is preferred that the fire extinguishing agent discharging unit 130 further include a filling pressure sensor unit 130c that detects a filling pressure at which the housing 130d is filled with a fire extinguishing agent.
[51] This is provided to solve the problem that fire extinguishing work is not performed due to the unsatisfactory discharge of the fire extinguishing agent in the case where the filling pressure is reduced below a predetermined pressure, since the discharge of the fire extinguishing agent is performed by the filling pressure of the housing 130d.
[52] The control unit 110 determines that a corresponding housing 130d has failed in the case where it is determined that the filling pressure, which is received from the filling pressure sensor unit 130c, is below a previously stored reference filling pressure, and, therefore, can determine the time for the exchange or replacement thereof.
[53] In that case, the filling pressure sensor unit 130c transmits information about the discharge ID number of a corresponding fire extinguishing agent discharging unit 130. It is preferred that the control unit 110 automatically determine which train car has a failed fire extinguishing agent discharging unit 130 by determining the fire detection ID number that matches a received discharge ID number and determining the train car number that matches the fire detection ID number.
[54] Meanwhile, in accordance with a second embodiment of the present invention, the fire detection units 120 located in respective train cars are assigned fire detection ID numbers that match the respective train car numbers of the train cars. The fire ex¬ tinguishing agent discharging units 130 are also assigned discharge ID numbers that match the respective train car numbers of the train cars.
[55] As illustrated in FIGS. 5 and 7, the respective train cars of a train are assigned, for example, train car numbers A to J. Furthermore, the fire detection units 120 installed in respective train cars are assigned fire detection ID numbers a to j. Moreover, the fire extinguishing agent discharging units 130 installed in respective train cars are assigned discharge ID numbers Al to Jl that match the train car numbers, respectively.
[56] Accordingly, in the case where a fire is detected in the fire detection unit 122 that is assigned the fire detection ID number b, a signal related to the fire detection ID number b is transmitted to the control unit 110. The control unit 110 can determine which train car is on fire by determining which train car has the train car number B that matches the fire detection ID number b.
[57] Furthermore, the control unit 110 causes fire extinguishing work to be performed in a corresponding train car by determining the discharge ID number Bl that matches the train car number B and operating only the actuator 132a of the fire extinguishing agent discharging unit 132 that corresponds to the discharge ID number Bl.
[58] Furthermore, it is preferred that camera units 150, which are assigned camera ID numbers A2 to J2 that match the train car numbers, be provided in respective train cars. The control unit 110 captures the image of the interior of a train car on fire by operating a camera unit 152 having a camera ID number B2 that matches a train car number B, and transmits the image to the engineer's room or a station building 175
through the data transceiver unit 180.
[59] Furthermore, it is preferred that the fire extinguishing agent discharging unit 130 further include a filling pressure sensor unit 130c that detects a filling pressure at which the housing 130d is filled with a fire extinguishing agent.
[60] The control unit 110 determines that a corresponding housing 130d has failed in the case where it is determined that the filling pressure received from the filling pressure sensor unit 130c is below a previously stored reference filling pressure, and, therefore, can determine the time for the exchange or replacement thereof.
[61] In that case, the filling pressure sensor unit 130c transmits information about the discharge ID number of a corresponding fire extinguishing agent discharging unit 130. It is preferred that the control unit 110 automatically determine which train car has a failed fire extinguishing agent discharging unit 130 by determining a train car number that matches the discharge ID number.
[62] As described above, with the automatic train fire extinguishing system according to the first and second embodiments, which train car is on fire can be immediately detected and countermeasures can be rapidly taken. Furthermore, which one 132 of the fire extinguishing agent discharging unit 130 has no fire extinguishing agent can be determined. Moreover, the time for the replacement of a housing 132d that is filled with a fire extinguishing agent can be easily determined.
[63] As described above, train car information, including the train car number of a train car in which a fire is occurring, information about the time for the replacement of the fire extinguishing agent discharging unit 130 and the image of the interior of the train car is transmitted to an engineer's room or station building through the data transceiver unit 180, thus enabling current status to be determined in real time and be rapidly dealt with at the time of fire.
[64] Furthermore, it is possible to allow the status of a train car to be determined in real time by transmitting the image of the interior of the train car to the engineer' s room or station building in a normal situation as well as an emergency situation.
[65] Furthermore, it is preferred that manual input units 160 be provided in respective train cars so as to also allow such fire extinguishing work to be manually performed in the case of a fire. Moreover, it is preferable to include an alarm unit 165 so as to allow passengers to be rapidly evacuated from a corresponding train car in the case of a train fire.
[66] Furthermore, it is preferred that communication terminals 170, such as interphones, be provided in respective train cars, so that the occurrence of an emergency can be reported to the engineer's room or the control room of the station building 175 as the same time that automatic or manual fire extinguishing work is performed.
[67] Furthermore, it is preferred that the fire detection unit 120, the fire extinguishing
agent discharging unit 130, the control unit 110, the alarm unit 165, the input unit 160, the camera unit 150, the data transceiver unit 180 and the communication terminal 170 be supplied with auxiliary power by an auxiliary power supply unit 190, such as a battery, when an emergency, in which power is not supplied due to a power failure, a fire or the breakdown of the pantograph of a train car, occurs.
[68] With this, even if an emergency in which power is not supplied occurs, the system can be stably operated and rapidly extinguish the fire.
[69] Furthermore, in accordance with the preferred embodiment of the present invention, fluoroketone compounds are used as the fire extinguishing agent. Fluroroketones, such as CF , CF , or (O)CF(CF ) , are substances that are formed by substituting fluorine for carbon atoms in a ketone molecule. Fluroroketones have the properties of colorlessness and odorlessness, and fluorine has the property of stability. Accordingly, fluoroketones do not conduct electricity and rapidly evaporate as soon as they come into contact with flames or smoke when discharged into a fire, so that fluoroketones can be used as the fire extinguishing agent. Fire Protection Fluid Novec 1230, developed by U.S. "3M", may be employed as the fire extinguishing agent. Novec 1230 has been recognized as a clean fire extinguishing agent by the National Fire Protection Association (NFPA), and is registered under the title of "FK5-1-12."
[70] With reference to FIG. 8, the fire extinguishing process of the automatic train fire extinguishing system according to the first embodiment is described below.
[71] First, the train car numbers of the train cars of a train, the fire detection ID numbers of the fire detection units 120 that match the train car numbers, the discharge ID numbers of the fire extinguishing agent discharging units 130 that match the fire detection ID numbers, and the camera ID numbers of the camera units 150 that match the fire detection ID numbers are stored at step SIlO. The fire detection unit 120 monitors whether a fire is occurring in real time at step S 120. When the fire is occurring, a fire signal is transmitted to the control unit 110 and the control unit 110 determines the fire detection ID number of the fire detection unit 120 that transmitted the fire signal at step S 130.
[72] The control unit 110 causes the valve 130b to open by operating the actuator 130a of the fire extinguishing agent discharging unit 130 having the discharge ID number that matches the determined fire detection ID number, so that the fire extinguishing agent is sprayed through the nozzle unit 140 to the train car in which the fire is occurring. Furthermore, the control unit 110 captures the status of the interior of the train car having the fire in real time by operating the camera unit 150 having the camera ID number that matches the fire detection ID number at step S 140.
[73] The train car number determined at step S 140 and the captured image data are transmitted to the engineer's room or the control room of the station building 175. In
response to these, an evacuation command or an alert broadcast is issued to passengers at step S 170. Accordingly, the train car in which the fire is occurring and the current status of the train car can be immediately determined, and countermeasures can be rapidly taken.
[74] Meanwhile, with reference to FlG. 9, the fire extinguishing process of the automatic train fire extinguishing system according to the second embodiment is described below.
[75] First, the train car numbers of the train cars of a train, the fire detection ID numbers of the fire detection units 120 that match the train car numbers, the discharge ID numbers of the fire extinguishing agent discharging units 130 that match the train car numbers, and the camera ID numbers of the camera units 150 that match the train car numbers are stored at step S210.
[76] The fire detection unit 120 monitors whether a fire is occurring in real time at step
S220. When a fire is occurring, a fire signal is transmitted to the control unit 110 and the control unit 110 determines the fire detection ID number of the fire detection unit 120 that transmitted the fire signal at step S230.
[77] The control unit 110 determines the train car number that matches the determined fire detection ID number at step S240, and causes the valve 130b to open by operating the actuator 130a of the fire extinguishing agent discharging unit 130 having the discharge ID number that matches the determined train car number. Thereby, the fire extinguishing agent is sprayed through the nozzle unit 140 to the train car in which the fire is occurring. Furthermore, the control unit 110 captures the status of the interior of the train car having the fire in real time by operating the camera unit 150 having the camera ID number that matches the fire detection ID number at step S250.
[78] The train car number determined at step S240 and the image data taken at step S250 are transmitted to the engineer's room or the control room of the station building 175. In response to these, an evacuation command or an alert broadcast is issued to passengers at step S270. Accordingly, the train car in which the fire is occurring and the current status of the train car can be immediately determined, and countermeasures can be rapidly taken.
[79] Meanwhile, FlG. 10 is a diagram illustrating a process capable of automatically de¬ termining the time for the repair or replacement of the fire extinguishing agent discharging unit 130.
[80] With reference to the drawing, a reference filling pressure required for spraying the fire extinguishing agent from the fire extinguishing agent discharging unit 130 in the case of a fire is previously stored at step S310. The train car numbers of the train cars of a train, the fire detection ID numbers of the fire detection units 120 that match the train car numbers, and the discharge ID numbers of the fire extinguishing agent
discharging units 130 that match the fire detection ID numbers are previously stored at step S320.
[81] The filling pressure of the housing 130d of the fire extinguishing agent discharging unit 130, which is filled with the fire extinguishing agent, is detected at step S330. The control unit 110 compares the detected filling pressure with the previously stored reference filling pressure at step S340. If the detected filling pressure is below the previously stored reference filling pressure, the control unit 110 determines that the corresponding fire extinguishing agent discharging unit 130 has failed, determines the fire detection ID number that matches the discharge ID number of the corresponding fire extinguishing agent discharging unit 130, and finally determines the train car number that matches the fire detection ID number at step S350.
[82] The control unit 110 gives the alarm about the determined train car number and the failure details of the corresponding fire extinguishing agent discharging unit 130 through the alarm unit 165 at step S360.
[83] Thereby, the failure and the time for the replacement of each fire extinguishing agent discharging unit 130 provided in each train car can be automatically determined without the need for an inspector to manually detect whether it is in a normal.
[84] In the meantime, at step S320, only the train car numbers of the train cars and the discharge ID numbers of the fire extinguishing agent discharging units 130 that match the train car numbers are stored. Thereafter, at step S350, it is possible to determine the directly matched train car number from the discharge ID number of the fire ex¬ tinguishing agent discharging unit 130.
[85] Meanwhile, the state in which the nozzle units 140 and the fire detection units 120 are provided in the train cars of the train, the occurrence of a fire is determined by the control unit 110 separate from the fire extinguishing agent discharging unit 130 and fire extinguishing work is conducted, as described above, is illustrated and described. However, unlike this, the nozzle unit, the fire detection unit and the control unit can be directly provided in the fire extinguishing agent discharging unit and fire extinguishing work can be conducted.
[86] Alternatively, unlike that, the nozzle sensor and an impact sensor can be directly provided in the fire extinguishing agent discharging unit, and impact pressure is detected by the impact sensor when the fire extinguishing agent discharging unit is thrown to a location where a fire is occurring. In this case, the fire extinguishing agent is sprayed from the nozzle unit.
[87] Up to now, the present invention has been illustrated and described in conjunction with the preferred embodiments that exemplify the principle of the present invention. However, the present invention is not limited to the construction and operation that have been illustrated and described above. Rather, those skilled in the art will fully
understand that many changes and modifications can be made without departing from the spirit and scope of the attached claims. Industrial Applicability
[88] The present invention can automatically and rapidly extinguish a fire in the case of a fire, and easily manage the history of a fire extinguisher. Furthermore, the present invention can be used as an automatic train fire extinguishing system that can monitor the status of a fire.