True Duct Smoke Detectors with Relay Output and Analogue Output, VSD-series

Duct Smoke Detectors VSD-series

The true duct smoke detector VSD-series has been developed from a proven design using modern devices to provide effective and reliable detection of smoke in ventilation systems.

Detection of smoke for true duct smoke detector VSD-series is achieved by monitoring a carefully controlled infrared beam (IR-detection, obscuration) within a perforated tube which is inserted into the ductwork. This method senses smoke directly within the duct, eliminating the problems associated with conventional detectors mounted in sampling boxes.

Circuitry incorporated in the design of the true duct smoke detector controls the infrared beam continuously. This ensures that the true duct smoke detector response will remain constant throughout operation of the system.

sensing probe for duct smoke detector VSD-series

External influences including background pollution, airborne dust and low level electrical interference frequently found in commercial and industrial applications,
a common source of problems with some other types of true duct smoke detectors, are selectively filtered by the electronics thereby providing the highest sensitivity to smoke combined with effective rejection of short term disturbances that would otherwise give a false alarm.


The true duct smoke detector is equipped with a reset botton outside the enclosure.

reset button for duct smoke detector VSD-series


The true duct smoke detectors features variable sensitivity and an advanced signal damping circuit which can be bypassed for testing purposes.

  • Outputs
  • - Relay SPDT 1A@24Vdc, 120 Vac
    - Analogue 2-10 Vdc

  • Relay output for closing fan/damper motor
  • Damped output or undamped output
  • The analogue output signal 2-10 Vdc can transmit
    smoke or service alarm (dirt level) to BEMS system
  • Manual reset or auto reset
  • Power supply 24 Vac/dc
  • pcb for duct smoke detector VSD-series

  • Analogue output status levels
  • < 2 Vdc = Sensor fault
    < 3-7 Vdc = Normal operation
    < 7-9 Vdc = Optics require cleaning
    > 9,5 Vdc = Smoke alarm

    compensation ovk for duct smoke detector VSD-series


    The standard probe lenghts are 300 mm and 600 mm for the true duct smoke detectors.

    The true duct smoke detector is simple to clean and does not need to be removed from the duct work when cleaning is required.

    An LED bargraph visually indicates the smoke density and service state of the optical duct smoke detectors (VSD 302 and VSD 602 only) and this signal is available as an analogue output to communicate with a building automation system.


    4 different true duct smoke detectors types in VSD-series

    VSD 301
    True duct smoke detector, 300 mm probe length

    VSD 601
    True duct smoke detector, 600 mm probe length

    VSD 302
    True duct smoke detector, 300 mm probe length, with LED bargraph display

    VSD 602
    True duct smoke detector, 600 mm probe length, with LED bargraph display

    VSD 301 is standard type and supplied at no minimum quantities.

    VSD 601, VSD 302 and VSD 602 are supplied on request
    at minimum 10 pcs.


Download datasheet

Technical data sheet True Duct Smoke Detectors with Relay Output and Analogue Output, VSD-series.pdf


Download CE declaration of conformity

CE declaration of conformity True Duct Smoke Detector, VSD-series.pdf


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