Method and a system for improving alarm reliability of smoke fire detector

A method for improving the alarm reliability of smoke fire detectors, which is applied to smoke detectors with dual spectrum or bidirectional scattering design, the method comprising the following steps:

• S1, setting updated background thresholds, alarm thresholds and an aerosol type threshold;
• wherein the updated background thresholds mentioned include updated long-period background thresholds of an optical detection path A and an optical detection path B, which are respectively marked as ThAL and ThBL, and updated short-period background thresholds, which are respectively marked as ThAL and ThBL;
• wherein the alarm thresholds mentioned include a fire smoke alarm threshold Th1Fire and an interfering substance alarm threshold Th2Fire;
• and wherein the aerosol type threshold mentioned includes a scatter light power ratio threshold Thr for identifying aerosol types;
• S2, initializing a background value of the smoke detector;
• S3, regularly updating a detection value;
• S4, regularly updating a long-period background value;
• S5, updating a short-period background value according to a threshold method;
• Judge judging whether the absolute differences between real-time detection values VA and VB of the two optical detection paths and respective short-period background values BAS and BBS are greater than the corresponding updated short-period background thresholds ThAS and ThBS;
• and if so, proceeding to Step S6;
• Otherwiseotherwise, update updating the short-period background values BAS and BBS, and returning to Step S3;
• S6, identifying an aerosol type;
• calculating the scatter light power ratio a of an aerosol, and judge judging whether a is less than Thr or not;
• if yes, identifying the aerosol type as fire smoke, proceeding to Step S7;
• otherwise, identifying the aerosol type as an interfering substance, proceed to Step S8;
• S7, Giving giving an alarm of fire smoke alarm;
• judging whether the difference between the real-time detection value VA of the optical detection path A and the updated long-period background threshold ThAL is greater than the fire smoke alarm threshold Th1Fire;
• if yes, continue continuing to judge whether the real-time detection value VB of the optical detection path B is greater than the updated long-period background threshold ThBL;
• and if also yes, giving an alarm;
• otherwise, proceeding to Step S8;
• and
• S8, Giving giving an alarm of interfering substances;
• judging whether the difference between the real-time detection value VA of the optical detection path A and the updated long-period threshold ThAL is greater than the interfering substance alarm threshold Th2Fire, if yes, giving an alarm.