Aspirating smoke detector

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An aspirating smoke detector (ASD ) is a system used in active fire protection, which consists of a central detection unit that draws air through the pipeline to detect smoke. The sampling chamber is based on a nephelometer that detects the presence of smoke particles suspended in the air by detecting light dispersed in the chamber. ASD can usually detect smoke before it is visible to the naked eye.

In most cases aspirating smoke detectors require a fan unit to pull air samples from a protected area through a pipeline, as well as for Wagner, ProSeries Safe Fire Detection and ASD Xtralis systems.

Video Aspirating smoke detector

History

In 1970, the Commonwealth Scientific and Industrial Research Organization (CSIRO) used a nephelometer to conduct research on forest fires. Furthermore, the Australian Postmaster-General Department involves CSIRO to investigate technologies that may prevent service disruption due to fire. After selecting a sample site to conduct the research, CSIRO suggested that the nephelometer should be used as a benchmark for APO fire tests. It is installed to monitor the level of smoke in the air passage behind the mechanical ventilation system, utilizing the output display of the recorder diagram.

At the end of several weeks of testing, it was found that no commercially available fire detection technology was suitable to prevent damage to telephone equipment. One technology that is really promising is the nephelometer itself.

In 1979, Xtralis, then IEI Pty Ltd., produced and sold the air sampling equipment they call VESDA (Very Early Smoke Detection Apparatus). The company redesigned the detector in 1982 to provide lower reliability, features, size and cost for the export market. The ASD system has gained popularity because of their ability to sense smoke long before the catastrophic incident.

Maps Aspirating smoke detector

Design

The ASD design corrects the deficiencies of conventional smoke detectors by using a sampling pipe with multiple holes. Air samples are captured and filtered, removing any contaminants or dust to avoid false alarms and then processed by a highly sensitive and centralized laser detection unit. If smoke is detected, system alarms are triggered, and signals are then processed through a centralized monitoring station within a few seconds.

Unlike passive smoke detection systems, including spot detectors, ASD systems actively draw smoke to detectors through drill holes in piped systems that run across protected areas. Additionally, the ASD system combines integrity monitoring to ensure a warning is raised at any time ASD's ability to detect smoke is interrupted. This does not occur in passive devices that are generally only electrically monitored without the ability to determine if smoke can actually reach the detection element.

The ASD system combines more than one alarm level. This allows the ASD system to provide early warning of an event, which prompts an investigation at the earliest early stage of fire when it is easily overcome. Other alarm levels can be configured to provide fire alarm input to the fire system as well as release the suppressor system. The sensitivity of ASD alarms can be configured and can be programmed to levels ranging from thousands of times more sensitive than conventional detectors, to much less sensitive. The detector works best in non-volatile environments. They can also be used in computer cabinets to alert users to overheated computer cables or individual computer components.

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Installation and placement

ASD is suitable for environments where highly sensitive smoke detection capabilities are required. This keeps them fit in clean rooms; areas containing goods easily damaged by fire, such as tobacco, electronic chambers and liquids and highly combustible gases. Often, a normal point detector will recognize the danger of being too late, because the smoke often does not reach the ceiling fast enough to allow the fire to be detected in a timely manner.

Because they can be easily hidden, pipelines fit in environments where point detectors can be considered aesthetically pleasing, such as offices, apartments and hotel rooms. This factor also makes them suitable in locations where point detectors can be easily damaged, such as in correctional facilities.

Although high sensitivity ASDs they can be used in dusty or dirty environments during the correct design, installation and maintenance process are followed. Most ASD products can accommodate a wide range of environments and applications - from enclosed spaces and open to the cleanest or dirtiest environments, including telecommunications, control rooms, sewage treatment, mining, and more.

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See also

• Carbon monoxide detector
• Hot detector
• Smoke detector

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References

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External links

• Detect smoke in the air channel
• Three Wavelength Integrating

Source of the article : Wikipedia