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Talking about the False Reporting Phenomenon and Improvement Method of Fire Detector

Talking about the False Reporting Phenomenon and Improvement Method of Fire Detector

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First, the working principle of fire detector
Fire detectors are an important part of the building fire alarm system, also known as probes or sensitive heads. Its mission is to detect the occurrence of a fire, send a fire signal to the alarm system, and alert people. How does the detector detect the fire? When a fire occurs, smoke, flame or high temperature will inevitably occur. The detector is sensitive to these. It will change the normal state due to contact with them, causing changes or displacements of current, voltage or mechanical parts. During the transmission process, a fire signal is sent to the fire control room, and the location and location of the fire are displayed. According to this situation, we classify fire detectors into three categories: smoke, temperature, and light.
1, smoke detector
One is an ionized smoke detector that interferes with the normal operation of charged particles, causes current and voltage changes, and destroys the balance between the internal and external ionization chambers. The sensor generates an alarm signal; the other is a photo-sensing detector, which has a light-emitting element and a light-sensitive element. The light normally emitted by the light-emitting element is incident on the photosensitive element through the lens, and the circuit remains normal, if smoke is present. Blocking, the light reaching the photosensitive element is significantly weakened, so the photosensitive element converts the change of the light intensity into a change of the current, and sends an alarm signal through the amplifying circuit; and the other is a pipe-sucking smoke detector, passing the smoke The reflection or scattering action produces a photo-sensitive current that is primarily used on ships. This kind of detector uses semiconductor components, which is small in size, low in price, strong in shock resistance and long in life. It has great development prospects.
2, temperature detector
One is the use of metal thermal expansion and contraction characteristics: under normal circumstances, the detector circuit is in an open state, when the ambient temperature rises to a certain value, the metal expands and extends to make the circuit connected, signaling; The kind uses a characteristic of fusible metal to fix a low-melting point alloy in the detector circuit. When the temperature rises to its melting point, the metal melts, and the contact force is made by the force of the spring, the circuit is connected, and an alarm is issued. signal. There is also a temperature difference type that senses an alarm when the rate of temperature rise exceeds a certain value.
3, optical radiation detector
One is an infrared light radiation detector. When the substance is burning, it will produce flickering infrared radiation. The lead sulfide infrared photosensitive element in the detector will sense this and generate an electric signal, which will be alarmed after amplification. The other is the ultraviolet radiation detector, which is utilized. The ultraviolet light generated when the organic compound is burned causes the electrode of the ultraviolet light sensitive tube to excite ions, and the circuit is alarmed by a relay or the like.
Second, the technical status and development of fire detection systems
1. Status of technology
Since the reform and opening up, with the rapid development of economic construction and fire protection, China's fire protection industry has entered a period of vigorous development. China's fire-fighting electronics industry is part of China's fire protection industry, and it is also a part of the higher technology gold content, and it is also the fastest-growing part. The general-purpose general fire alarm equipment can be produced internationally. Facing the development opportunities of high technology and the international competition in the domestic market, fire protection products have developed into more reliable, intelligent and networked early fire detection and alarm technologies. The first difference between the traditional fire alarm system and the modern fire alarm system is mainly the performance of the detector itself. The switch detector is changed to a qualitative leap on the analog sensor, and the smoke concentration, the rising rate or other sensing parameters are transmitted to the controller in analog values, so that the system determines that the data processing capability and the degree of intelligence of the fire are greatly increased. Reduce the probability of false alarms. The second difference is that the signal processing method has been completely improved, that is, the analog signal in the detector is continuously sent to the controller for evaluation or judgment, and the controller uses an appropriate algorithm to identify the false or real fire alarm, judge the degree of development and detect the state of contamination. This higher quality signal processing technology means that the system has a higher "intelligence". Increasing system reliability is the development direction of modern fire detection and alarm technology. Intelligent fire detection and alarm system can be divided into three types according to its intelligent distribution: detection intelligence, second, monitoring intelligence, and third, detection intelligence and control intelligence. The latter is a more intelligent system with higher reliability, but the disadvantage is high cost.
2. Development prospects
The expectation for the automatic fire alarm system is that it first requires the system to detect the fire early, and secondly eliminates the false alarm and lowers the cost of the system. The fire intelligent alarm system may eventually develop a robotic intelligent alarm system. The rapid development of modern fire alarm systems on the other hand is the emergence of composite detectors and a variety of new detectors, and the detection performance is getting better and better. Among many new technologies and new products, one has improved the commonly used ionized smoke into a composite detector with a combination of CO sensors. Since the change in CO content in the air is earlier than the generation of smoke and flame, it has a higher response speed. The development prospects are very good. Another point-type laser smoke detector has a sensitivity 50 times higher than that of the current photo-electric smoke detector. It is used to replace the aspirating smoke alarm system to provide very early fire detection, and the cost is much lower, and the application prospect is very high. it is good.
In recent years, the application of infrared beam smoke detection, cable type fixed temperature fire detectors, flammable gas detectors, etc. in fire engineering has been increasing, and corresponding product standards and design specifications have been established. The detector works like a photo-electric smoke detector, except that the smoke does not have to enter the sampling chamber of the point-type photo-electric smoke detector. The linear beam detector can replace several point-type smoke detectors on a path of up to 100m, which has the advantages of large protection area, high installation position, high relative humidity and high electric field environment. It is suitable to protect large indoor and outdoor places, especially suitable for the protection of places where it is difficult to use point detectors or even point detectors.
As part of the building automation system, the intelligent fire protection system can communicate with the security system and the intelligent fire protection system of other buildings in the intelligent building, and alarm and transmit information to the superior management system. It is the urban fire dispatching command system and the urban fire prevention management system. Networked operations with the city's integrated information management network provide effective information on the status of fire and building fire protection systems and share data and information with other city management centers. The breadth and depth of the fire automation system incorporated into the construction equipment automation system vary widely from country to country. Generally speaking, most of the fire-fighting automation systems in domestic intelligent buildings are independent and self-contained. This self-contained fire-fighting system is independent of buildings and security systems, and has poor interconnectivity. When global events occur, no other forms will be formed. The system cooperates with the function of linkage and centralized resolution of events.