High sensitivity smoke detectors

A diagrammatic representation of the Vesda aspiring smoke detection system.So-called ‘aspiring’ smoke detection devices are air sampling smoke detectors that are designed to provide the earliest warning of a potential fire and so to provide enhanced safety in diverse applications. Vesda aspiring smoke detectors reliably measure extremely low concentrations of smoke. They are used in warehousing, telecommunications and electrical facilities, mining, cold storage, manufacturing plants and power stations, as well as the healthcare and commercial sectors. The system is especially well suited to applications where unobtrusive detection is required, in art galleries, for example, modern offices and heritage buildings.

It also carries approval for use in hazardous areas (Factory Mutual Class 1 Div 2) where air quality is poor or temperatures are extreme. Duncan Boyes, chairman of the Centa Group  which specialises in fire protection, notes, “An important feature of this fire detection system is that it allows time to investigate a potential fire and to intervene if necessary, so that damage, downtime and costs caused by a fire can be avoided. The early warning alarm also gives sufficient time for the building to be evacuated.

“The multiple warning levels of the system can be used to trigger different responses at different stages of a fire, from controlling air conditioning, to suppression release.”

The system encompasses a network of pipes with small sampling holes in them, as well as capillary sampling tubes. It operates by continually drawing air into the pipe network via a high efficiency aspirator. Samples of the air are then passed through a dual stage filter before entering the calibrated detection chamber where the air is exposed to a laser light. If smoke is present, light is scattered within the detection chamber and this is instantly identified by the highly sensitive receiver system. The signal is then processed and presented graphically on a monitor.

The detectors can be linked to a fire alarm control panel, a software management system or a building management system via relays or a high level interface, so that the appropriate responses are triggered according to the indicated stage of a fire. The Vesda air sampling smoke detection system is distributed, installed and supported throughout Southern Africa by the Centa Group.

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