Photoelectric smoke detectors (including aspirating detectors) generally use relative scales to measure smoke. On the one hand, the relative measurement can compensate the pollution of the detection chamber, and it also has a certain inhibitory effect on the background value smoke, but it is undeniable that the relative measurement method will Compensating for the slowly rising smoke, resulting in a false report of the fire, so the relevant standards, there is a requirement for the addition of the smoke sensor, the compensation speed can not exceed the speed of the smoke rise, for the general smoke sensor, due to the low sensitivity, when the alarm The fire is in a rapid rise phase, and the problem is not big. However, for very early fire alarms, because the sensitivity is very high, in the early stage of the fire, the smoke rises very slowly, and the relative measurement is easy to compensate the smoke, resulting in a false report of the fire, so the European standard It is stipulated that the compensation learning time of the early-stage fire detector should not be less than 24 hours. Due to the slower compensation, the problem of contamination of the detection chamber can be eliminated. The background smoke suppression effect is limited, and the smoke under the average value is also compensated. In order to better capture the smoke generated by the fire, speed up the fire alarm response time. Absolute metering can be used. Absolute metering requirements for the detection chamber are very high, and the technology is very complicated. Only industry leaders such as Aikelis can do it. After years of research and testing, Ruishi has invented an algorithm that can achieve absolute metering of smoke in a common detection chamber (general smoke detector), which solves the problem of relative metering and eliminates the effects of dust, water vapor and PM10 . It also has a great inhibitory effect on PM2.5 . After testing in the case of highly contaminated PM2.5 ( 180ug/ cubic), the alarm threshold can be set at 0.0125% m/obs , and the sensitivity is more than 10 times that of the very early fire. , greatly improved the ability of early detection of fire.