Showing papers on "Fire detection published in 1995"

Analysis of signature patterns for discriminating fire detection with multiple sensors

Abstract: Incorporating intelligence into a fire detector so that it can recognize signature patterns is intended to permit prompt fire detection while allowing the detector to discriminate between signatures from fire and nonfire sources. The primary purpose of this preliminary study is to investigate the patterns of signatures associated with fire and environmental sources using small-scale experiments. We generated products from a wide range of conditions, from flaming or pyrolyzing samples, to heated samples and samples obtained with an atomizer. We also measured gas concentrations, light obscuration, and temperature to characterize the products. By analyzing the data, we identified trends from which an elementary expert system can be formulated to identify the source of the airborne products. Several patterns are evident. The maximum CO2 concentrations achieved during experiments with flaming fires are significantly greater than the maximum CO2 concentrations achieved during experiments with nonflaming fires (pyrolyzing fires, heated liquids, and environmental odors). The nonflaming sources can be identified based on the CO and metal oxide sensor peak measurements. Except for three experiments using pyrolyzing solids, the peak CO concentration is greater—though the Taguchi detector response is less—for nonflaming fires than for environmental sources. Subsequent application of a neural network properly classifies all except one pyrolyzing fire.

Multispectral remote sensing of biomass burning in West Africa

Abstract: Remote sensing measurements provide a vauable means of determining the extent of burning areas and of estimating the overall distribution of pollutant sources (identified from experimental studies) in time and space. This distribution has to be taken into account in the boundary conditions of chemistry atmospheric models. Recent methods developed for the remote sensing of active fires in tropical or temperated forest zones, have been found to be completely inadequate for fire detection on West African savannas. In order to accurately estimate the active fire distribution in the function of different sorts of West African savannas (Sahelian, Sudanian and Guinean) and forests, a multispectral methodology has been developed based on NOAA/11-AVHRR satellite data, with the purpose of eliminating as much as possible the problems related to large surface heterogeneity, confusion and bias, produced by clouds, smoke, haze, background emissivities, etc. Unlike other methods, the results show that the multispectral method, in spite of its selectivity, provides realistic results, and does not under- or over-estimate the number of fires that can be sensed by the satellite. Consequently, this methodology is more appropriate than the simplest ones for a systematic sensing of this phenomenon.

A robust fire detection algorithm for temperature and optical smoke density using fuzzy logic

Abstract: Multi sensor based fire detection (MSbFD) systems are one of the important current developments in automatic fire detection technology. The two main objectives of this progress are the still unacceptable false alarm behaviour and improvements in the fire detection capabilities (i.e. shorter detection times) of fire detection systems. The use of more than one sensor in a fire detector gives an improved image of the environment monitored and hence allows a safer alarm decision. Multi sensor technology allows but does imply the enhancement of fire detection systems in the desired directions. The crucial point is the evaluation and interpretation of the signals produced by the monitored phenomena. This signal processing (detection algorithm) mostly determines the detectors capabilities. Due to the availability of microcontrollers applicable to fire detector technology with its severe technical constraints (i.e. power consumption) modern signal processing techniques (neural networks, fuzzy logic) can be used. The paper presents a MSbFD algorithm using two fire parameters (temperature and optical smoke density). These two sensors were chosen since ionization systems may become increasingly difficult to apply because of the environmental regulations being imposed on them. The evaluation and processing of the sensor signals is carried out by the use of fuzzy logic. The concept of the algorithm is outlined and its performance and robustness in the fire and the non-fire case is shown by simulation results.

Fire detecting/extinguishing apparatus and water discharging nozzle therefor

Abstract: A fire detecting/extinguishing apparatus according to the present invention is comprised of a fire detecting unit which monitors to detect a fire within a monitoring area, the fire detecting unit stepwise scanning in a vertical direction while scanning the fire monitoring area in the vertical direction at each step of the horizontal scanning; a water discharging unit having a water discharging nozzle for discharging water to the monitoring area, the water discharging unit being rotatable in the horizontal direction, the water discharging unit being directed toward a position of the fire based on the fire detection by the fire detecting unit; a swinging unit which swings the water discharging unit in the horizontal direction; and a casing in which the fire detecting unit and the water discharging unit are housed as a single unit. Further, the apparatus of the present invention includes a cover fixed to a side of the water discharging nozzle which is opposite to the side of the water discharging nozzle. The cover is capable of rotating together with the water discharging unit, and the cover is flush with a front wall of the casing when the water discharging nozzle is housed in the casing.

Fire safety research in microgravity: How to detect smoke and flames you cannot see

Abstract: Any design requiring the application of technology contains a challenge to achieve a safe design. Manned space flight requires the highest degree of attention to crew safety, thus understanding and recognizing all potential risks involved. An important area of concern is establishing design criteria for a reliable fire detection and suppression system. This has been a main target when designing the European pressurized manned module “Columbus Attached Laboratory” as part of the international space station. This paper describes experiments performed to investigate the behavior of fires and the fluid dynamics of suppression agents in microgravity by means of parabolic flight maneuvers as an aid for the development of a design of a fire detection and suppression system for the manned Columbus Attached Laboratory.

Apparatus for detecting a fire having a liquid filled sensor tube and compensation for changes in ambient temperature

Abstract: A fire detection system includes an elongated liquid filled tube with a fluid coupled alarm switch, with a flexible diaphragm which senses a change from the liquid to vapor phase in the presence of an overheat or fire condition to provide an alarm. To prevent false alarms due to normal expansion of the liquid under changing ambient temperature conditions, a compensator is provided which in one form is a pair of mechanically coupled bellow type containers, filled with the same liquid which will expand at the same rate as the fluid under normal ambient temperature conditions but in a fire condition will resist faster expansion thus causing the alarm switch to be actuated. In another embodiment, a bimetallic bellows is utilized to match the liquid expansion but resist greater vapor pressure. Yet in another embodiment the change in liquid flow rate due to a fire condition is sensed to prevent further accommodation to the normal increase in volume of the liquid. This is done by a flexible diaphragm or a floating seal ball.

Fire detection port

Abstract: A fire detection port installed in doors of occupied structures provides visible and audible signals on one side of a door in the event of fire on the other side of the door.

Use of the ARGOS fire risk analysis model for studying chinese restaurant fires

Abstract: The fire risk in Chinese restaurants in Hong Kong is analyzed using the ARGOS fire risk analysis model developed at the Danish Institute of Fire Technology. A sample size of fifteen Chinese restaurants with different floor areas and fire load densities is considered. Fire simulations are performed for two cases by assuming a PU foam furniture fire occurring in the dining hall and a kerosene fire in the kitchen. Correlations are derived between the floor area and the predicted maximum hot gas temperature, the corresponding smoke layer interface height and the cost of damaged stock in the restaurants. The effectiveness of fire protection systems including sprinkler systems and smoke vents in controlling the fire is also discussed.

Exploratory research on nonthermal damage to electronics from fires and fire-suppression agents

Abstract: Electronic equipment is expected to operate reliably under normal conditions as well as under foreseeable abnormal conditions, particularly in life-critical and environmentally sensitive applications. One foreseeable abnormal condition to which electronic equipment may be subjected at least once during its life-cycle is a fire environment. Such an environment may include the thermal and corrosive effects in the immediate vicinity of the fire and the nonthermal effects associated with smoke contamination, humidity and corrosion in remote locations. Direct thermal effects are generally so severe that reasonable remedial actions may not be feasible. Fortunately, such effects are frequently restricted to a fairly small zone, often through the use of automatic fire detection and suppression systems. On the other hand, the thermal decomposition products of smoke and fire suppression agents resulting from even a small fire may permeate a building and cause nonthermal damage to electronic equipment in locations remote from the actual fire. With ever-increasing reliance being placed on electronic equipment in all types of applications and the consequent increase in value concentrations, nonthermal damage from fires and fire suppression agents is a topic of growing interest. The purpose of this exploratory research is to characterize nonthermal damage mechanisms, consequences, and potential preventive and remedial actions using a physics-of-failure approach.

Super sensitive fire detection/extinguishing system

Abstract: PROBLEM TO BE SOLVED: To provide a system to detect smoke generated early from a fire inside a device and to partially extinguish the fire. SOLUTION: This system comprises a sampling tube 2 for each switch board group on which plural nozzles are attached to suck air flow inside each device 7, a super-sensitive detector 3 to detect an early fire attached on each panel group, a fire extinguishing gas tank 5 in which fire extinguishing gas necessary to extinguish initial fire is stored to be supplied for each device 7, and a 3-way valve 6 attached at each crossing point of a release tube 51, to which fire extinguishing gas is released, and the sampling tube 2. By this system, a fire breaking out inside the devices 7 can be detected at a very early stage, and the fire extinguishing gas can be released at a limited part inside the device 7 from the fire extinguishing gas tank 5 using the sampling tube 2. COPYRIGHT: (C)1997,JPO

Disaster prevention guiding and displaying system

Abstract: PURPOSE: To properly perform the refuging guidance when a disaster is generated and to reduce human damage in relatively large-scale facilities such as a hospital and a hotel, etc CONSTITUTION: Fire alarms 11a, 11b, detect the generation of a fire when the state is generated and transmit the detections to the receiver 12 provided within a disaster prevention center When the receiver 12 receives a fire detection signal, the receiver outputs fire alarm data showing a fire generated location, etc, to a guidance data transmitter 13 This guidance data transmitter 13 prepares the optimal refuging guidance data based on fire alarm data D and transmits the data to the guidance display panels 15a, 15b, provided on a refuging guidance route by a transmission antenna 14 Each of the guidance display panels 15a, 15b has each specific address, receives the refuging guidance data transmitted from the guidance data transmitter 13, and flexibly changes the arrow and the guide information showing the direction refuging according to the data contents and displays them COPYRIGHT: (C)1996,JPO

Fire detection device with disruptive parameter correction

Abstract: Fire detection device (1) comprising a fire sensor which measures a first physical quantity and generates a measuring signal, the latter being affected by a second physical quantity which is different from the first. The device also includes a correction sensor (4) for measuring the second physical quantity and generating a correction signal. The fire sensor and the correction sensor are connected to a microprocessor (2) in which is stored a curve representing a normal operating value i0 of the measuring signal based on the value of the correction signal in the absence of a fire. The microprocessor is programmed to calculate i0 based on the correction signal and to determine the presence of a fire when the mesuring signal is not included in the range of values determined about i0.

Automatic fire detection and extinction system for automobiles

Abstract: Each of e.g. 3 flame detectors (22) has an infra-red sensor in a heat-resistant case, mounted near an infra-red monitoring source, e.g. on the bulkhead, directed at fuel-related components. Thermal sensors (e.g. 3) (24) are mounted above the engine. Two extinguishers with pyrotechnic releases and pressure-type monitoring (28) are operated (30) from the controller (18). 5 discrete flashes, identified within 2.5 sec set up a "pre-alarm" state. A 3 sec verification stage follows. If the flash-rate persists during this period, and at least two detectors respond, one extinguisher is activated. Detection is then suspended for 8 sec, then resumed, ab initio. The second extinguisher deals with any subsequent fire. System conditions and alarms are displayed, with a manual override, at a driver's control panel (20).

Optical-based UV-IR gas detector for monitoring hydrocarbons and toxic gases

Abstract: The infrared and ultraviolet emission spectra of hydrocarbons and toxicants was measured and analyzed as compared to theoretical data at room temperature. Based on this data we constructed an electro-optical gas detector for monitoring low concentration of flammable paraffins, aromatics, and toxic hydrogen-sulfide. The optical method uses two wavelengths at several spectral bands: the signal and the reference which is sampled at a region where the hazardous gas does not absorb at all. Our apparatus is an innovative system that provides fast and reliable explosion detection at different lower explosion levels (LEL). As well, it can provide identification of low concentration of toxicants in the range of parts per million. The apparatus includes a fire detection option that can offer at the same time an automatic activation of fire suppression or neutralization system. It can detect paraffins in the range between 0.03 to 20 LEL per 1 meter by using the ultraviolet spectral band. At both regions the accuracy is about 20%. This open-path, line-of-sight gas detector can monitor and transmit an alarm signal prior to occurrence of fire or explosion.

Smoke detection in low-G fires

Abstract: Fires in spacecraft are considered a credible risk. To respond to this risk, NASA flew fire detectors on Skylab and the Space Shuttle (STS) and included them in the design for International Space Station Alpha (ISSA). In previous missions (Mercury, Gemini and Apollo), the crew quarters were so cramped that it was not considered credible that the astronauts could fail to observe a fire. The Skylab nodule included approximately 20 UV fire detectors. The space shuttle has 9 ionization detectors in the mid deck and flight deck and Spacelab has six additional ionization detectors. The planned detectors for ISSA are laser-diode, forward-scattering, smoke or particulate detectors. Current plans for the ISSA call for two detectors in the open area of the module and detectors in racks that have both cooling air flow and electrical power. Due to the complete absence of data concerning the nature of particulate and radiant emission from low-g fires, all three of these detector systems were designed based upon 1-g test data. As planned mission durations and complexity increase and the volume of spacecraft increases, the need for and importance of effective, crew independent, fire detection grows significantly. This requires more knowledge concerning low-gravity fires and how they might be detected. To date, no combustion-generated particulate samples have been collected for well-developed microgravity flames. All of the extant data come from drop tower tests and therefore only correspond to the early stages of a fire. The fuel sources were restricted to laminar gas-jet diffusion flames and rapidly overheated wire insulation. These gas-jet drop tower tests indicate, through thermophoretic sampling, that soot primaries and aggregates (groups of primary particles) in micro-g may be significantly larger than those in normal-g (ng). This raises new scientific questions about soot processes as well as practical issues for particulate detection/alarm threshold levels used in on-orbit smoke detectors. Furthermore, it is widely speculated but unverified that the aggregates will grow to very large scales in a microgravity fire of longer duration than available on the ground. Preliminary tests in the 2.2 second drop tower suggest that particulate generated by overheated wire insulation will also be larger in microgravity than in normal gravity. TEM grids downstream of the fire region in the WIF experiment as well as visual observation of long string-like aggregates, further confirm this suggestion. The combined impact of these limited results and theoretical predictions is that direct knowledge of low-g combustion particulate as opposed to extrapolation from 1-g data is needed for a more confident design of smoke detectors for spacecraft.

Next generation fire suppressants

Abstract: Spectrex, Inc., located in Cedar Grove, NJ is a manufacturer of fire detection and suppression equipment. Spectrex is one of the original pioneers in high speed fire detection and suppression systems for combat vehicles. Spectrex has installed fire suppressions systems in thousands of combat vehicles and ships throughout the world. Additionally, they manufacture flame explosion detectors, ship damage control systems, and optical gas and vapor detectors. The culmination of several years of research and development has recently produced an innovative electro-optical continuous monitoring systems called SharpEye 20/20I IR(sup 3) and SAFEYE that provide fast and reliable gas, vapor, aerosol, flame, and explosion detection. SharpEye 20/20I IR(sup 3) is a self-contained triple spectrum flame detector which scans for oscillating IR radiation (1 to 10 Hz) in the spectral bands ranging from 4.0 to 5.0 microns and uses programmed algorithms to check the ratio and correlation of data received by the three sensors to make the system highly immune to false alarms. It is extremely sensitive as it can detect a 1 x 1 square foot gasoline pan fire at 200 feet in less than 3 seconds. The sensitivity is user programmable, offering 4 ranges of detection. SAFEYE is comprised of a selected number of multispectral ban microprocessors controlled detectors which are in communication with one or more radiation sources that is projected along a 600 feet optical path. The signals from the selected narrow bands are processed and analyzed by highly sophisticated algorithms. It is ideal for high risk, remote, large areas such as petroleum and chemical manufacturing sites, waste dumps, aircraft cargo bays, and ship compartments. The SAFEYE will perform direct readings of the presence or rate of rise of concentrations of gases, vapors, or aerosols at the range of parts per million and provide alarms at various set points at different levels of concentrations.

Fire detection system and fire sensor

Abstract: PURPOSE:To easily and speedily test the operation of the fire detection system without employing a multiplex transmitting means which is high in cost. CONSTITUTION:This system is equipped with plural fire sensors A (A1 A4) which perform contact output operation when a fire is detected and a receiver 1 which receives contact output signals from those fire sensors A1-A4; and the respective fire sensors A1-A4 are the fire detection system which takes a self-diagnosis when receiving a specific test signal from the receiver 1 and performs specific contact output operation when the result of the self-diagnosis is normal. Then the respective fire sensors A1-A4 perform the contact output operations for their self-diagnosis results specific times, set characteristically to the fire sensors A1-A4, after the test signal is received from the receiver 1, so that the fire sensors A1-A4 performs the contact output operation at different time.

Optical-based UV-IR gas detector for environmental monitoring of flammable hydrocarbons and toxic gases

Abstract: The infrared and ultraviolet emission spectra of hydrocarbons and toxicants was measured and analyzed as compared to theoretical data at room temperature. Based on this data we constructed an electro-optical gas detector for monitoring low concentration of flammable paraffins, aromatics and toxic hydrogen-sulfide. The optical method uses two wavelengths at several spectral bands: the signal and the reference which is sampled at a region where the hazardous gas does not absorb at all. Our apparatus is an innovative system that provides fast and reliable explosion detection at different lower explosion levels (LEL). As well, it can provide identification of low concentration of toxicants in the range of parts per million. The apparatus includes a fire detection option that can offer at the same time an automatic activation of fire suppression or neutralization system. It can detect paraffins in the range between 0.03 to 20 LEL per 1 meter by using the ultraviolet spectral band. At both regions the accuracy is about 20%. This open-path, line-of-sight gas detector can monitor and transmit an alarm signal prior to occurrence of fire or explosion.

Optical systems for security engineering

Abstract: An overview of the main optical methods used today in the detection of fire is presented, including optical smoke detection by light scattering and obscuration, as well as infrared flame detection. Further, intrusion detection by detection of emitted infrared radiation of human bodies is discussed.

Fire detecting system using optical fiber

Abstract: PURPOSE:To provide a fire detecting system which permits setting of sensors not to impair the beauty of cultural inheritance buildings, etc., to be adapted with these sensors and for which optical fibers are used as temp. sensors capable of detecting positions. CONSTITUTION:At least one piece of the optical fibers 2 are extended and disposed with regular arrangement for each of respective units over the entire surface of a unit plane part, such as roof of a wooden building 1 or a unit space such as under the floor. The prescribed length of such optical fibers 2 is determined as a temp. sensor unit and the fire detecting sensors in which these temp. sensor units continue are composed of the optical fibers 2. The scattering positions of light are detected by utilizing the echoes generated by scattering of the incident light from the incident light ends of the optical fibers 2, by which the fire detection positions at every sensor unit are identified.

Space-based forest fire detection concept

Abstract: Small, incipient wildfires in the boreal forest can be detected with a space-based infrared sensor that uses currently available technology. At night, wildfires with a temperature of 700 K or more and an area of 1 m2 should be visible if there is a clear line of sight to the sensor. Sensor refinements and signal processing could enhance this level of detection. Clouds, topographical variations and the forest canopy may obscure the line of sight, so that multiple looks would significantly improve the probability of detection of a small fire. The relatively long revisit time of a satellite-based sensor is a constraint of the fire management application. Although the cost and revisit time of a spaceborne sensor are currently too high for it to replace airborne sensors, there is an important role as an adjunct sensor operating at night. Many of the specifications of an infrared sensor for wildfire detection are similar to those for space-based surveillance applications, so that useful infrared imagery from space may become available to the forest management community at relatively low cost.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Alarm triggering device, especially for a fire detection facility

Abstract: The device comprises a housing (10) including a viewing window (22), a pressure plate (26) capable of being forced from a normal rest position to an actuating or triggering position. An indicating plate (40) bearing an indicator mark is translatably mounted on the plate (26) and is elastically biassed from a locking position to a release position in which the indicator mark is opposite the viewing window.

Fire information receiver

Abstract: PURPOSE:To transmit quickly fire information by allowing a control unit to collect the presence of lots of call request signals. CONSTITUTION:A control unit 10 calls a power supply unit 20, a display operation unit 30, a fire detection unit 40 and a relay unit 50 sequentially and circulatingly through a data line DL to control transmission reception of various information or the like. When a fire sensor senses the breakout of a fire and transmits a fire signal to the unit 40, an MPU 41 transmits a call request signal to the unit 10 via a call request signal line CL to detect a call signal. The unit 10 sends the address of the unit 20 and a state information return instruction immediately through the line DL and awaits the return of the information of the unit 20, receives return state information and conducts the operations above to each of the units 30, 40, 50. Even when the number of the units controlled by the control unit is increased, fire information is quickly transmitted to the control unit.

Self-supported type intelligent moving body

Abstract: PURPOSE:To detect a fire point in a preset passage for0 easy, low-cost fire extinguishing action. CONSTITUTION:An extinguishing nozzle 3 blows off extinguisher in an extinguishing cylinder 4 over an extinguishment area at a certain distance from a moving body 1. A fire detecting sensor 2 detects a fire point and outputs a fire detection signal and an angle signal. A CPU 8 performs survey action in accordance with data and program stored in a memory 5. The CPU 8 to which the fire detection signal is supplied calculates a distance to the fire point from the angle signal, moves the moving body 1 via a travel control 7 to match a center effect point in the extinguishment area to the fire point, when the fire point is outside the extinguishment area, and gives instructions to an extinguishing nozzle control 6 to blow off the extinguisher.

Fire control system

Abstract: The fire detection system (2) uses a pair of IR cameras (11,12), supported by a rotary axis (10), coupled to a controlled drive (22), with an associated rotation angle detector (28). A processor (31) is used to digitalise the thermal images provided by IR cameras and to calculate the room coordinates of detected hot spots within the bunker, in conjunction with the data provided by the rotation angle detector. Pref. the bunker contains a test element (51) with a periodically-controlled heated surface, used to check the function of the fire detection system and/or a number of heated calibration elements (38), for calibrating the room coordinates of the refuse bunker.

Fire detection device

Abstract: PURPOSE:To speedily discriminate which of a heat detection part or a smoke detection part acts and to prevent the delay of an alarm and wrong information CONSTITUTION:A detection circuit 2 where a terminal resistance part 3, the heat detection parts 4 whose impedance changes by the detection of heat, and the smoke detection parts 5 whose impedance changes by the detection of smoke are connected in parallel between two connection lines 6 and 7 is provided First voltage VH is given to the detection circuit 2 at regular time, and second voltage VL which does not operate the smoke detection parts 5 based on the detection operations of the heat detection parts 4 and (or) the smoke detection parts 5 is given to the circuit Thus, the detection part 4 or 5 which has acted by detecting heat or smoke, is discriminated based on the level of current Ir flowing in the detection circuit 2 at the time of giving second voltage VL