VESDA
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In firefighting a VESDA™ (Very Early Smoke Detection Apparatus) is a brand of aspirated smoke detector which is capable of detecting the microscopic particles of combustion also known as smoke. Generally aspirating smoke detectors work by drawing air in through a network of small-bore pipes laid out above or below a ceiling in parallel runs covering a protected area. Small holes are drilled into each pipe to form a matrix of holes (sampling points), providing an even distribution across the pipe network. The air sample is drawn past a sensitive optical device (in the case of VESDA™ a robust solid state laser) tuned to detect the extremely small particles of combustion. A VESDA™ detector may be used to trigger automatic fire responses, such as a gaseous fire suppression system, in high value, or mission critical areas such as archives or computer server rooms.
VESDA™ detectors provide multiple levels of alarm threshold - Alert, Action, Fire 1 and Fire 2. Thresholds may be set at levels across a very wide range of smoke levels. This allows the earliest possible notification of a developing fire allowing intervention before a fire develops beyond the smouldering stage - allowing increased time for evacuation, or the implementation of Emergency Response or Business Continuity Plans. Fire thresholds may be used to notify local or municipal emergency responders and ultimately to discharge fire suppression systems.
VESDA™ very rarely causes false alarms, however it can be configured to be so sensitive that it may require temporary changes to alarm thresholds when smoke from bonfires, barbequeues, kilns or other outdoor fires drifts near the building or when smoke machines are used in the building. Alternatively VESDA™ detectors offer a referencing capability where a reference detector allows the influence of widespread smoke to be eliminated while maintaining absolute sensitivity in the areas where it is required.
VESDA™ is a registered trademark of Vision Fire & Security Pty Ltd.
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