False alarm and prevention of the hottest fire aut

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False alarm and prevention of automatic fire alarm system

automatic fire alarm system is a safety device to monitor the fire in the installation site. It is an automatic fire-fighting facility set up in buildings or other places in order to find and report the fire as soon as possible, and take effective measures to control and extinguish the fire in time. The automatic fire alarm system is generally composed of trigger devices (including fire detectors and manual fire alarm buttons), fire alarm devices, fire alarm devices and power supplies, fire control equipment, etc. In the actual use of the building, the false alarm phenomenon of the fire detector of the device occurs from time to time, which affects the normal use effect of the building. A group of human-machine interface operation controllers. This paper briefly describes the types of false positives, the causes of false positives, and the preventive measures that can be taken

first, the types of false positives

false positives are divided into danger false positives and safety false positives: danger false positives refer to the fact that a large amount of smoke and temperature are produced when a fire occurs and the system cannot send an alarm signal, which is also called no alarm; False alarm of safety refers to the alarm when there is no fire, which is also called false alarm

second, the causes of false positives

the causes of false positives are relatively complex, which is a subject of concern and research by many fire experts

1. The false alarm problems caused by the quality and function of the accessories in each control link of the detector and alarm system are generally not easy to be completely eliminated

the detector of the early automatic fire alarm system can only output the signal value of a single sensor, and the sensor with a single function cannot cover the whole fire broadband, and the fire information carried by a single signal value is very limited. From a technical point of view, it can maximally suppress the false positives caused by circuit reasons, structural reasons and even EMI, which are the reasons for the rise and fall of the electronic universal experimental machine shared by technicians. However, it is not very effective in practice

2. In the design process, the project is recognized and widely used by the majority of customers. Another factor causing false positives is the improper selection of detectors by designers or the improper installation position

3. The construction is not in accordance with the specifications and Jerry built

4. Improper system operation

III. methods to reduce false positives

in order to prevent false positives, make the fire alarm system accurately display and record the location of the fire, and send all kinds of acoustic and optical signals and linkage instructions to fire-fighting equipment in time, in addition to improving the technical level of the manufacturing industry and product functions, all processes should be strictly controlled in terms of design, construction, maintenance, use and management

1. Improve system functions

(1) there are two main methods to solve the false alarm of early fire alarm system. One is to increase the number of judgments or add a delay circuit to eliminate the incoming mailbox: alice zhang@reedexpo.com.cn Transient interference from the circuit itself or the environment; Second, the ion chamber or photoelectric smoke sensing chamber and related circuits are carefully designed to compensate for the environmental impact. However, the actual effect is not ideal, and the false alarm rate is about 3 times/100 Year

(2) select new intelligent fire alarm system. The new distributed intelligent fire alarm system is mainly composed of distributed intelligent detectors and distributed intelligent controllers with network functions. The new distributed intelligent detector has built-in multiple sensors, which complement each other. The combination judgment of multi-dimensional parameters is adopted, and the information of multiple sensors is analyzed by CPU. When judging, according to the different reactions of different sensors to smoke within a certain time interval, the detection range is expanded, the sensitivity is improved, and the false alarm rate is reduced. Because the new distributed intelligent detector can be programmed according to the specific installation location of the detector, so that the detector and the detection environment match each other, so that the detector can achieve the best detection effect; At the same time, special programming can also make the detector conveniently compensate for the influence of temperature, humidity and dust. Improve the false alarm caused by non fire reasons

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