Method for detecting fire with light section image to sense smoke

A system for detecting fire by smoke-emission analysis, comprising:

• a plurality of infrared radiation arrays mounted in an area to be protected against fire and operative to generate discrete infrared light beams passing across the area and being interceptable by smoke particles emitted upon development of a fire condition;
• a plurality of detectors mounted in the area at a distance from the infrared radiation array and each operative to detect a respective discrete infrared beam and to generate a respective video signal in response to detecting, the generated video signals representing attenuation of the discrete infrared beams by smoke particles;
• a computer operative to process the video signals to determine at least a possibility of a fire condition in the area and to generate an alarm in response to the processing of the video signals in response to determining the fire condition in:
• a first fire recognition mode, wherein each of the processed signals is compared to an alarm threshold and enables the alarm upon exceeding the alarm threshold,
• a second fire recognition mode, wherein each processed signal is sequentially compared to the alarm threshold and a turning threshold to determine tendency corresponding to the fire condition in the monitored area, the processor enabling the alarm only if a respective processed signal exceeds the turning threshold, and
• a third fire recognition mode, wherein the alarm is enabled if all of the processed signals exceed the turning threshold.

A system for detecting fire by smoke-emission analysis, comprising:

• a plurality of radiation arrays mounted in an area to be protected against fire and operative to generate a plurality of discrete light beams passing across the area and being interceptable by smoke particles emitted upon development of a fire condition;
• a plurality of detectors mounted in the area at a distance from the infrared radiation arrays and each operative to detect a respective discrete light beam and to generate a respective video signal in response to detecting of the light beam, the generated video signals representing attenuation of the discrete light beams by smoke particles, each light beam being characterized by a respective intensity reduced upon penetration through smoke articles in accordance with the following formula
• Iλ=Iλ0exp(−KL),
• wherein Iλ is the detected light bam, Iλ0 is the intensity of the radiated light beam, L is the average run length of the light beam, and K is the extinction coefficient and is a function of the diameter of the smoke particles and their density;
• a processor operative to process the video signals to determine at least a possibility of a fire condition in the space and to generate an alarm in response to the processing of the video signals in response to determining the fire condition.

A system for detecting fire by smoke emission analysis, comprising:

• a plurality of radiation arrays mounted in an area to be protected against fire and operative to generate a plurality of discrete light beams passing across the area and being interceptable by smoke particles emitted upon development of a fire condition;
• a plurality of detectors mounted in the area at a distance from the infrared radiation arrays and each operative to detect a respective discrete light beam and to generate a respective video signal in response to detecting, the generated video signals representing attenuation of the discrete light beams by smoke particles;
• a processor operative to process the video signals to determine at least a possibility of a fire condition in the space and to generate an alarm in response to the processing of the video signals in response to determining the fire condition, the processor being a computer operable in a first fire recognition mode, wherein each of the processed signals is compared to an alarm threshold and enables the alarm upon exceeding the alarm threshold;
• a second fire recognition mode, wherein each processed signal is sequentially compared to the alarm threshold and a turning threshold to determine tendency corresponding to the fire condition in the monitored area, the processor enabling the alarm only if a respective processed signal exceeds the turning threshold;
• and a third fire recognition mode, wherein the alarm is enabled if all of the processed signals exceed the turning threshold.