The focus of this project was to design and create a combinational smoke detector to sense different fire characteristics. Research was completed on the background of detectors and different thresholds of characteristic signatures from a fire that could be identified. Fire signatures identified for the detector were smoke, carbon monoxide and heat. Individual sensors that could recognize these signatures were used in the design of a smoke detector that could reduce the number of false alarms caused by nuisance sources by looking for a combination of signals to indicate alarm.

Smoke detectors are a vital commodity in every occupied building in the world. Smoke detectors help to detect and indicate a threat to nearby inhabitants in the event of a fire. Smoke detectors allow people to become aware of their surroundings and alert them to seek safety. It is extremely important that smoke detectors remain a reliable product around the world. There is little or no room at all when it comes to efficient fire detection and saving the lives of many civilians.

Smoke detectors have become common in households across the United States since the 1970’s when they were first recognized as being highly important in saving lives. Since the introduction of smoke detectors into homes, fire related deaths have dropped by nearly 50%.1 There are also new studies out that show 65% of fire deaths occur in homes that either don’t have a smoke detector or the smoke detector was not operating. This goes to show how important smoke detectors can be in saving lives.

Combinational Smoke Detector for Fire AlarmThe purpose of this project was to investigate, design, and create a way to detect a fire while reducing the number of false alarms that occur. This project focused on the characteristics fire signatures and how they could be used to detect only a fire. Research and interviews were completed to determine what the most common smoke characteristics were and how they could be detected.

It was determined that when detecting a fire with just the technology of smoke obscuration sensors it was very sensitive to false alarms. However, if smoke obscuration was measured in conjunction with signals caused by temperature and carbon monoxide then it may be possible to limit the number of false alarms.

Current technologies used in smoke detectors are: Ionization smoke detector, Photoelectric smoke detectors, Heat Detectors, Carbon Monoxide Sensors. There are also combinational heat and smoke detectors, as well as ionization and photoelectric detectors in one device. These detectors are advances from a single sensor detector, but there is still room for improvement. There is introductory technology where the use of multiple sensors in conjunction with each other is being made, however not many devices are currently available.

Research was conducted that found thresholds for each of these fire characteristics and then they were implemented into a design for a combinational smoke detector. The smoke detector was designed and fabricated for testing to see if indeed a combination of these three fire characteristics could decrease the number of false alarms.

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