| Current methods of fire detection in the most | | | | because the threshold concentration of smoke, on the |
| commonly used are two broad categories, namely, | | | | photoelectric type is to change the current intensity of |
| temperature detection and smoke detection. Smoke | | | | light scattering light. In addition to the intensity of |
| detection is conducive to early detection of fire, and | | | | photocurrent and the concentration of smoke, but also |
| this "early" is the core of the pursuit of fire prevention, | | | | by the luminous efficiency of LED, the drive current |
| so Fire Monitoring System, use smoke detectors | | | | strength, and optical receiver photoelectric conversion |
| majority. Smoke detectors are divided into ionic and | | | | efficiency of the tube, even with the LED and receiving |
| photoelectric type two categories. Early widely used | | | | control the direction of the launch and receive surface |
| mostly to ionic, photoelectric type, use less. One | | | | distribution function and the LED and receiver tube |
| reason seems to comparison, ion is more sensitive in | | | | installation has great relationship. In short, the impact of |
| the "early smoldering smoke" (smoke particle size | | | | too many factors, but also the necessary precision in |
| smaller). Only in respect sensitivity of this point, can be | | | | the context of most of them can not be ignored. The |
| resolved from the sensitivity setting, it is not keen on | | | | ion type, the smoke into, its direct effect is to change |
| the early people ion type smoke detector main reason. | | | | the gate voltage, while the gate voltage is the voltage |
| In fact, people in the radioactive sources ionic worry | | | | from the ion chamber and ion chamber of the |
| has always been there, but because ionic Probe The | | | | mechanical structure and the decision of radioactive |
| calibration technique is easy to grasp, to achieve a | | | | sources. As the partial pressure ratio can be |
| very easy product sensitivity is easy to maintain | | | | mechanical parts geometry precision, and accuracy of |
| consistency. The photoelectric-type probe, was initially | | | | the sources match made sufficiently accurate (as |
| Environment And stray light interference, when the light | | | | compared with the optical control type is easier). |
| source and photo on the tube and light maze solution, | | | | Threshold concentration of smoke in the simulation, you |
| the interference problem is basically solved. More | | | | can simply set the control by the voltage ion chamber, |
| troubled by the current general factory calibration | | | | to achieve sufficient accuracy of the simulation. ? |
| technique, compared with ionization smoke detector | | | | From the above mentioned simulation of the |
| calibration, the calibration of photoelectric detectors, | | | | relationship with the smoke can be seen, ion calibration |
| relatively more difficult, if improper methods, the | | | | can be done very simply. Calibration, the ion chamber |
| sensitivity of the product are often scattered yield is | | | | at the top with only required analog voltage. The |
| also affected. Therefore, many manufacturers are still | | | | photoelectric emission drive current If can, LED |
| abandoned development and production of | | | | light-emitting efficiency and intensity distribution of the |
| photoelectric and ionic. ? | | | | direction of the surface, the photoelectric conversion |
| As economic development, the rapid growth of social | | | | efficiency of photoelectric tubes and receive direction, |
| wealth, fire prevention more attention. This makes the | | | | each light and other optical properties of the maze to |
| rapid growth of the number of detectors used, ion | | | | achieve sufficient accuracy consistency , and the two |
| probe reprocessing of radioactive sources have | | | | pipe installation precision and optical properties of an |
| become a major concern by people Environmental | | | | ideal, you can not calibrate. If the optical output signal |
| protection Potential problems. Therefore, when the | | | | for the function of various factors as variables, known |
| photoelectric type smoke sensor quality assurance, | | | | from the differential theory: the differential output signal |
| and the price quite, people will be more willing to use | | | | (error) will be a function of the variable, and by the |
| photoelectric smoke detector. So the situation is | | | | individual variable differential (error) of, on the whole , |
| forcing ionic dominance and give out photoelectric | | | | the error is much greater than when a single variable. If |
| sensor. In particular, the future development of analog | | | | only one or two good control, then after a |
| Fire Alarm Technology to replace the volume of alarm | | | | comprehensive tobacco scattering, the uncertainty of |
| switch technology or "quasi" (pseudo) analog detection | | | | the individual electrical simulation of compensation can |
| technology, is the general trend. Sensitivity and | | | | be taken to reach the sensitivity required. However, in |
| consistency required to produce the optical line sensor, | | | | practice, usually there are many aspects of device |
| increasing the rate of qualified products, to master the | | | | performance and technology on the discreteness, and |
| production of the last pass - high-precision calibration | | | | they are all significantly affect the sensitivity of the |
| technology has become a problem to be solved. | | | | detector, which is difficult to simulate by way of |
| As a calibration photoelectric system, which is different | | | | electrical compensation. So the simulation is more |
| from the ionic calibration system where the threshold | | | | difficult. |
| on the concentration of smoke in its simulation. This is | | | | |