Intrinsically Safe Gas Detectors FGD3 Series

Carbon Dioxide Gas Detector

(using infrared sensor technology)

Intrinsically Safe Carbon Dioxide Gas Detector


  • Standard ranges available are 0-2%, 0-5% or 0-100% volume Carbon Dioxide, CO2.
  • Plug-in, separately certified infrared Ex d sensor.
  • Suitable for use in Zones 1 and 2 hazardous areas.
  • Three wire connection.
  • 8 to 24 volt dc operation (also requires an additional supply of 5.8 to 7.5 volts dc to power the sensor).
  • Industry standard 4 to 20mA output.
  • Digital display
  • Single operator calibration.
  • Marine version available.
  • Optional weather guard available.


The FGD 3 Infrared Carbon Dioxide Gas Detector incorporates the latest generation of compact sensors incorporating infrared technology for the accurate detection of Carbon Dioxide concentrations over various ranges up to 100% volume. The detectors use the industry standard 4-20mA current loop to convey the gas levels detected to a control unit. This means that under zero gas conditions 4mA is drawn from the supply, and under full scale gas conditions 20mA is drawn from the supply. The current varies linearly for gas levels between zero and full scale. The detector heads use a three-wire connection. While the loop current supplies the power required by the detector head electronics within the detector head, a second supply must be provided to power the infrared sensor and its associated circuitry.

Marine Version

A marine version of the FGD3 is also available. This version is housed in a cast aluminium enclosure to provide higher RFI immunity where high power portable radios are used in the close confines of a vessel. The enclosure is plated and painted in order to withstand the harsh salt spray environment of the marine industry. The digital display is fitted with a sliding stainless steel front cover which remains over the display window when not being viewed thereby maintaining the RFI shielding properties of the enclosure during normal operation.

FGD3 Weatherguard

An optional weather guard is available for installations exposed to the atmosphere or contaminants and is also suitable for use in other areas where hosing down takes place. The weather guard reduces the possibility of water or other contaminants entering into the gas sensor thereby improving the overall reliability of the gas detector in harsh environments.The weather guard is attached with tamperproof screws to ensure that it is not inadvertently removed.

FGD3-IR Series Data Sheet

Hazardous Area Certification Data

Certificate Number - BAS 01ATEX2300
II 2 G Ex ia IIC T4 Gb (-20 deg. C <Ta< +60 deg. C)
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FGD3 Carbon Dioxide Detectors - Order Codes

Stock No. Description
SS412-2% FGD3 Carbon Dioxide Gas Detector - (4-20mA Output) - Range 0-2% volume
SS412-5% FGD3 Carbon Dioxide Gas Detector - (4-20mA Output) - Range 0-5% volume
SS412-100% FGD3 Carbon Dioxide Gas Detector - (4-20mA Output) - Range 0-100% volume
SS412-M-2% FGD3 Carbon Dioxide Gas Detector - Marine Version - (4-20mA Output) - Range 0-2% volume
SS412-M-5% FGD3 Carbon Dioxide Gas Detector - Marine Version - (4-20mA Output) - Range 0-5% volume
SS412-M-100% FGD3 Carbon Dioxide Gas Detector - Marine Version - (4-20mA Output) - Range 0-100% volume
SS475 FGD3 Series Protective Weather Guard
SS429 FGD3 Series Collector Cone
SS374 FGD3 Series Swivel Mounting Bracket
SS375 FGD3 Series Ceiling Mounting Bracket

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