Eblast - Hochiki New Sensors

Technology Guide High Performance Optical Chamber Typically photoelectric smoke sensors/detectors have been more sensitive to smoke emitted by smoldering fires and less sensitive to smoke emitted from flaming fires (see fig 5 on page 2). Generally if the sensitivity to the flaming fire is improved, the sensitivity to the smoldering fire would become very high, significantly increasing the possibility of unwanted alarms. Unwanted Alarms False alarms cost the Australian tax payer over $100 million in 2019. FRNSW alone, responded to approximately 48,000 calls with 97% being unwanted. Around 38% of all FRNSW calls are from Automatic Fire Alarms (AFA). AFA systems are a crucial component in fire detection for buildings and are designed to alert occupants and initiate quick responses by state brigades in the case of fires. AFA systems are required under building legislation, as prescribed by the National Construction Code, and are administered by Local Government Authorities. Chamber Design To produce a stable smoke sensor/detector with the minimum of unwanted alarms the sensitivity to smoke produced in smoldering fires should be reduced rather than increased. To overcome this problem Hochiki undertook a major research project to examine the key parameters of light scattering principles. Hochiki’s research found that redesigning the internal optical angle and chamber structure within the photoelectric smoke sensor/ detector, the chamber design could minimise the difference in sensitivity to smoke particles produced by flaming and smoldering fires. By honing this angle Hochiki developed the High Performance optical chamber that would be more equally responsive to all smoke types: Smoke Detection Principles When a light source (incident light) hits a smoke particle it is deflected and becomes scattered light, generally known as “backscatter”. The angle at which this light is scattered is known as the Scattering Angle. ALN-ASN/ ACC-ASN Current angle of internal optics results in a consistent response to each test fire SLV-AS Current angle of internal optics results in a consistent response to each test fire As theScattering Angle Increases the relative sensitivity of the smoke sensor/detector to the type of fire is reduced, allowing the sensor to give a flatter response across the different test fires (see fig 4 on page 2). The amount of “backscatter” is dependant on particle size and colour of smoke: The above diagram represents the intensity and scattering angle for kerosene smoke particles, the test for flaming fires producing black smoke. Note the low intensity The above diagram represents the intensity and scattering angle for paper smoke particles, the test for smouldering fires producing white smoke. Note the higher intensity and wider angle. fig 1 fig 2 fig 3 Technology uide High Performance Optical Chamber Typically photoelectric smoke sensors/detectors have been more sensitive to smoke emitted by smoldering fires and less sensitive to smoke emitted from flaming fires (see fig 5 on page 2). Generally if the sensitivity to the flaming fire is improved, the sensitivity to the smoldering fire would become very high, significantly increasing the possibility of unwanted alarms. Unwanted Alarms False alarms cost the Australian tax payer over $100 million in 2019. FRNSW alone, responded to approximately 48,000 calls with 97% being unwanted. Around 38% of all FRNSW calls are from Automatic Fire Alarms (AFA). AFA systems are a crucial component in fire detection for buildings and are designed to alert occupants and initiate quick responses by state brigades in the case of fires. AFA systems are required under building legislation, as prescribed by the National Construction Code, and are administered by Local Government Authorities. Chamber Design To produce a stable smoke sensor/detector with the minimum of unwanted alarms the sensitivity to smoke produced in smoldering fires should be reduced rather than increased. To overcome this problem Hochiki undertook a major research project to examine the key parameters of light scattering principles. Hochiki’s research found that redesigning the internal optical angle and chamber structure within the photoelectric smoke sensor/ detector, the chamber design could minimise the difference in sensitivity to smoke particles produced by flaming and smoldering fires. By honing this angle Hochiki developed the High Performance optical chamber that would be more equally responsive to all smoke types: Smoke Detection Principles When a light source (incident light) hits a smoke particle it is deflected and becomes scattered light, generally known as “backscatter”. The angle at which this light is scattered is known as the Scattering Angle. ALN-ASN/ ACC-ASN Current angle of internal optics results in a consistent response to each test fire SLV-AS Current angle of internal optics results in a consistent response to each test fire As theScattering Angle Increases the relative sensitivity of the smoke senso /detector to the type of fire is reduced, allowing the sensor t give a flat er r sponse across the different test fir s (see fig 4 on page 2). The amount of “backscatter” is dependant on particle size and colour of smoke: The above diagram represents the intensity and scatterin ngl for kerosene smoke particles, the test for flaming fires producing black smoke. Note the low intensity The above diagram represents the intensity and scatter n angle for pap r smoke particles, the test for smouldering fires roducing white smoke. N te the high r intensity and wider angl fig 1 fig 2 fig 3 ec l y G i e High Performance Optical Chamb r Typically photoelectric smoke sensors/detectors have been more sensitive to smoke emitted by smoldering fires and less sensitive to smoke emitted from flaming fires (see fig 5 on page 2). Generally if the sensitivity to the flaming fire is improved, the sensitivity to the smoldering fire would become very high, significantly increasing the possibility of unwanted alarms. Unwanted Alarms False alarms cost the Australian tax payer over $100 million in 2019. FRNSW alone, responded to approximately 48,000 calls with 97% being unwanted. Around 38% of all FRNSW calls are from Automatic Fire Alarms (AFA). AFA systems are a crucial component in fire detection for buildings and are designed to alert occupants and initiate quick responses by state brigades in the case of fires. AFA systems are required under building legislation, as prescribed by the National Construction Code, and are administered by Local Government Authorities. Chamber Design To produce a stable smoke sensor/detector with the minimum of unwanted alarms the sensitivity to smoke produced in smoldering fires should be reduced rather than increased. To overcome this problem Hochiki undertook a major research project to examine the key parameters of light scattering principles. Hochiki’s research found that redesigning the internal optical angle and chamber structure within the photoelectric smoke sensor/ detector, the chamber design could minimise the difference in sensitivity to smoke particles produced by flaming and smoldering fires. By honing this angle Hochiki developed the High Performance optical chamber that would be more equally responsive to all smoke types: Smoke Detection Principles When a light source (incident light) hits a smoke particle it is deflected and becomes scattered light, generally known as “backscatter”. The angle at which this light is scattered is known as the Scattering Angle. ALN-ASN/ ACC-ASN Current angle of internal optics results in a consistent response to each test fire SLV-AS Current angle of internal optics results in a consistent response to each test fire As theScattering Angle Increases the relative sensitivity of the smoke sensor/detector to the type of fire is reduced, allowing the sensor t give a flatter response across the different test fir s (see fig 4 on page 2). The amount of “backscatter” is dependant on particle size and colour of smoke: The above diagram represents the intensity and scattering ngl for kerosene smoke particles, the test for flaming fires producing black smoke. Note the low intensity The above diagram represents the intensity and scatterin angle for pap r smoke particles, the test for smouldering fires roducing white smoke. N te the high r intensity and wider angl . fig 1 fig 2 fig 3