【 Weak current College 】 analog air tube line heat fire detection technology---Power By 【 China power house network 】

Summary: discusses analog air tube line heat fire detection technology's basic principles and key technical detection, and the composition of the detector and its application to do a simple introduction. Tags: analog; Air tube; Linear heat fire detection 1 preface in recent years, China's largest space buildings and underground building fires occur, because of the underground and the particularities of the large space building, common fire detection and alarm system cannot fast acquisition of fire gas temperature change information that cannot adapt to the harsh environment, it is difficult to meet the early detection and prediction of such fire requirements. Linear heat fire detection and alarm system with its unique heat detection methods and outstanding environmental performance, such as highway tunnels, subway station road, mining tunnel, underground large parking lots underground buildings and large public areas, markets, goods warehouse, storage tanks, etc. larger space building ideal means of fire detection and alarm, but also in recent years, fire detection and alarm technology hot spot. 2 the so-called ideal gas detection principle refers to the density is not too big, the pressure is too high (compared with atmospheric pressure) and the temperature is not too low (compared with room temperature) General gas, comply with the law of Boyle 's, cover · Lussac's law and Charlie's law. Certain quality m ideal gas equation: PV = mRT/M (1) type: P-gas absolute pressure, N/m2; V — gas volume, m3; M-gas mass, kg; M-molar gas mass, kg; R — the universal gas constant, Nm/(kg · K); T-thermodynamic temperature, K. When the gas volume to a certain value, the ideal gas equation available: P/T = constant. So certain quality of ideal gas in bulk to a certain value, which is proportional to the pressure and temperature. The air pipe line type heat detector probe tube (laying in the scene) sealed a quality of gas, the gas volume can approximate view does not change as temperature changes. When the probe tube or its surroundings temperature changes, detecting pipeline gas pressure change, after pressure sensors detect gas pressure variations can deduce detection lines surrounding temperature changes. According to the principle of gas continuous flow, in effective detection pipeline length (meets engineering applications and pressure sensors for pressure monitoring), guarantees that the probe tube first client and end pressure detection effectiveness. 3 detectors and key technology 3. 1 detector works by detecting line detector and micro-processing unit composed of two parts, which constitute as shown in Figure 1.
Detector works: sealed sensor gas path environment temperature changes cause sensing gas path air pressure changes, by a pressure sensor to detect changes in the level after the output signal, after filtering out the noise filter circuit, AD conversion circuit to analog information to digital, fed into the microcontroller (or microprocessor) for data operations, analysis and judgement, microcontroller (or microprocessor) after a certain algorithm processing, output temperature sensor status information to the output control circuit, fire alarm. Change the sensitivity setting to adjust the sensitivity level of the fire. Microcontroller (or microprocessor) timer (time interval can be selected) on fault detection circuit, control detection air pump, gas for sensing exert pressure, through the detection sensor gas path air pressure changes to determine whether the sensor has a gas leak, squeeze the phenomenon, realization detectors failure automatically display and automatic alarm.
3. the 2 main key technologies (1) micro-pressure sensing technology. Use of micro-pressure sensing technology to ensure the timely and accurate probe found that the fire, the implementation of early warning. (2) environmental temperature compensation technology. Detectors use ambient temperature compensation technology that can guarantee stable work in the detector detector effective working temperature range, avoid detector because of the ambient temperature changes appear false alarms, and ensures that the detector will always work in the sensor linear zone, there are enough dynamic range for fire detection. (3) gas automatic fault detection technology. Automatic detection probe tube blockage, leakage, realization detector fault auto show, auto alarm. 4 detector characteristics and main technical indicators (1) detector features sensitive element to gas medium delivery overheating or fire signal, does not require voltage (similar to fiber thermal detectors signal transmission through light), is the highest grade of intrinsically safe sensors, not receive electromagnetic interference signal, its reliability and stability are unparalleled in conventional detector; (2) linear differential fixed temperature detection, to fast and slow the overheating and fires can timely alerts; (3) automatic detection probe tube blockage, leakage, easy maintenance; (4) detector working voltage 18V ~ 36V; (5) probe static monitoring current less than 30mA; (6) fire current less than 40mA, fault current less than 20mA; (7) micro-treatment plant to provide the internal switch fire, fault output information, 0 ~ 20mA current and standard RS485 output, sounding tube allows the working temperature range is-40 ° c to + 150 ° c, micro-processing unit allows the working temperature range from-20 ° c ~ + 60 ℃; (8) the detection of pipe operating relative humidity up to 100%, the largest micro-processing plant in long-term operating relative humidity of 90% to 92%, short-term up to 100%; (9) sounding pipe length 20m ~ 100m; (10) micro-processing equipment, environment protection class IP65. 5 application notes 5. 1 main application range analog air tube line type heat detector is mainly used in road, rail and subway tunnel, multi-tiered underground and half open garage, ship transport deck, platform, airport lounge, garage for motor vehicles and machines, flammable gases, liquids, warehouses, drilling platforms,Painting workshop, oil tank, explosion-proof areas, chemical plants. 5. protection zone detection tube 2 settings (1) the application of road tunnels. For 1, 2 or 3 lane arch or circular tunnel, sounding pipes are always arranged in the middle of the tunnel (horizontal tolerances 0.5m), do not allow detecting tube side installation (normally), probe length 100m. For 1, 2 or 3 lane-topped tunnel, detection tubes suitable for placement in the middle of the tunnel (horizontal tolerances 0.5m), probe tube side installation allows distance: 2 lane, a minimum 0.5m; 3 lane, a minimum 1.0m, shown in Figure 2, the probe tube Max 100m. For more than three lanes-topped tunnel, at least install 2 probe tube, probe tube Max installation distance a = 10.0 m, b = 5.0m, shown in Figure 3, the probe tube Max 100m. (2) of the garage and similar areas. Probe tube Max 80m, allow spiral pipe laying, detection and detection tube a maximum allowable distance = 7.2m, sounding tube and the side walls of the maximum permissible distance b = 3.6m, shown in Figure 4. 5. the 3 probe tube installation requirements (1) probe tube laid should be based on both sides of the line of sight is not affected as the principle; (2) detection of pipe laying cannot only rely on copper tube below or above, consideration should be given to the minimum maintenance 0.5m distance; (3) tunnel sounding tube General laying in the tunnel as the principle; (4) detection tubes plastic holder (in high-temperature environment using metal fixation) laying directly on the ceiling, the tunnel if the cable carriers should not exceed 0.5m wide, can also be laying in the Bay below; (5) in the tunnel entrance, sounding tube terminal must remain with the tunnel portal; 25m distance (6) fixed support spacing as 0.8m; (7) each micro-processing unit allows only 1 root probe tube received, detecting tube can be a hard plastic tube or directly to the micro-processing unit. It connects two ways: first, from the tunnel to the side wall of the lateral part adopts copper tube probe tube, through the connector to connect the copper probe tube of plastic pipes, plastic wear protective casing will be laying next to micro-processing apparatus; Second, by detecting tube tunnel into the side wall of the lateral part adopts connector to a hard plastic wear protective casing downlead or smallpox