VESDA VLI

Built for the Environments That Defeat Other Detectors

Aspirating smoke detection has a weakness in dirty air. The system works by continuously drawing air through a filter and into an optical chamber, which means it also continuously draws in whatever else is in that air.

In a mine, a conveyor gallery, a processing plant or a petrochemical facility, that means dust, lint, fibres and oil mist. Filters clog, optics get coated and sensitivity drifts. The detector ends up either in fault, or recalibrated to the point where it’s no longer doing its job. On many industrial sites, aspirating detection has been ruled out for exactly this reason.

The VLI is the answer to that specific problem. Xtralis describes it as an industry first early warning aspirating detector for industrial applications and harsh environments, and the air treatment is where the engineering sits.

Four Stages Before the Chamber

Air passes through four separate stages before it reaches the detection chamber.

The Intelligent Filter splits the air sample. A smaller, unfiltered portion passes through a set of ultrasonic flow sensors, while the larger portion passes through a HEPA filter. That dramatically reduces the contaminants reaching the aspirator and detection chamber, extending the detector’s life in harsh conditions. Filter loading is constantly monitored, so the detector maintains consistent sensitivity across its whole operating life, rather than degrading silently.

A lint trap captures fibrous particles, the material that defeats most filters in textile, timber and agricultural environments.

A sub sampling probe acts as an inertial separator. Larger dust particles are less likely to pass through it, so they’re exhausted out of the detector rather than reaching the chamber.

A secondary filter provides the final stage. A third filter inside the chamber assembly then creates a clean air barrier that protects the optical surfaces.

That combination is what allows absolute detection without recalibration. On an industrial site, that’s the difference between a system that stays trustworthy and one that gets adjusted until it isn’t.

IP66, and Why That Saves Money

The enclosure is rated IP66, giving complete protection against dust and against strong water jets from any direction.

That does something specific to the installed cost. In most industrial applications, and particularly in very harsh environments, it removes the need for an expensive external IP enclosure. The detector goes on the wall, rather than inside a purpose bought housing that then has to be sealed and maintained in its own right.

The external housing has a rubberised finish, and a steel support bracket makes mounting easy.

Two Models

Specify the VLI-885 where the detector needs to sit on an existing VESDAnet network alongside other VESDA detectors. The VLI-880 suits a standalone installation reporting through relays.

Both have five relays, rated 2 A at 30 VDC: one fire, one fault and three configurable, each set as latching or non latching. General purpose inputs and relays can be expanded, and optional remote displays are available, with or without seven extra relays.

Flow Monitoring

Airflow is monitored by four sets of ultrasonic flow sensors at the detector inlets, with air path monitoring across the network. By comparing those readings with the unfiltered path in the Intelligent Filter, the detector tracks how the filter is loading and adjusts to keep sensitivity consistent.

Clean Air Zero is a user initiated feature that draws clean air into the chamber and takes a reference reading of the background, which supports consistent absolute detection and guards against nuisance alarms. Referencing takes account of external environmental conditions, where the outside air itself is the source of a nuisance alarm.

Commissioning and Maintenance

AutoLearn Smoke and Flow reduces setup time and sets alarm and flow thresholds from the actual conditions on site. Xtralis recommends running it for at least 14 days. In a variable industrial atmosphere, that’s more valuable than in a controlled one, because nobody can predict from a drawing what normal looks like in a conveyor gallery.

The detector is modular, with field replaceable parts, so a fault is repaired in place rather than by removing the unit. A local USB configuration port and easy access cable terminations reduce time on site, and the pipe ports accept both imperial and metric pipe.

ASPIRE handles pipe network design, and Xtralis VSC and VSM4 cover configuration, commissioning and maintenance. The VLI is compatible with existing VESDA installations. All alarms, service and fault events are logged with time and date stamps, holding up to 18,000 events.

Where It’s Used

Mines and underground infrastructure. Conveyors and transfer points. Manufacturing and processing plants. Petrochemical facilities. Timber and joinery works. Textile production. Waste and recycling facilities. Grain handling and agricultural storage. Cement and quarry plant. Warehouses with dusty operations. Workshops and vehicle maintenance areas. Any space where an aspirating detector would once have been ruled out because of contamination.