Loop-Powered 4–20 mA Gas Detector for Oxygen, Toxic and Carbon Dioxide Monitoring

The Dynament FGD4 Safe Area Gas Detector is a compact fixed gas detection solution designed for continuous monitoring of oxygen, toxic gases and carbon dioxide in non-hazardous environments. The FGD4 operates from an 8–24 V DC power supply and provides a standard 4–20 mA output for direct integration with gas detection control panels, PLCs, DCS and other industrial monitoring systems.

Trias Automation is an Authorized Distributor and Channel Partner for DwyerOmega and its associated instrumentation brands, supplying Dynament gas detection solutions for industrial measurement and monitoring applications in India.

The FGD4 features a plug-in replaceable gas sensor, compact enclosure, low-voltage operation and industry-standard analogue output, making it suitable for applications where reliable fixed-point gas monitoring and straightforward maintenance are required.

Key Features

• Fixed gas detector for non-hazardous / safe-area applications

• 8–24 V DC operating supply

• Standard 4–20 mA analogue output

• 2-wire loop-powered configuration for most gas types

• Plug-in replaceable gas sensor

• Electrochemical sensing for oxygen and toxic gases

• NDIR infrared sensing for carbon dioxide

• Compact and lightweight construction

• Enclosure protection up to IP66

• Sensor protection up to IP65

• Optional weather guard for additional environmental protection

• Internal ZERO and SPAN calibration buttons

• Optional handheld configuration unit for calibration and setup

• Multiple gas types and measurement ranges available

• Suitable for integration with industrial gas monitoring and control systems

Gas Detection Options

The Dynament FGD4 is available in multiple configurations depending on the gas being monitored and the required measurement range.

GasSensor TechnologyAvailable Measurement RangesAmmonia (NH₃)Electrochemical0–100 ppm, 0–1000 ppmCarbon Monoxide (CO)Electrochemical0–50 ppm, 0–100 ppm, 0–500 ppm, 0–1000 ppmChlorine (Cl₂)Electrochemical0–20 ppmHydrogen (H₂)Electrochemical0–1000 ppmHydrogen Chloride (HCl)Electrochemical0–30 ppmHydrogen Cyanide (HCN)Electrochemical0–30 ppmHydrogen Sulphide (H₂S)Electrochemical0–50 ppm, 0–100 ppm, 0–200 ppmNitrogen Dioxide (NO₂)Electrochemical0–20 ppmNitric Oxide (NO)Electrochemical0–50 ppm, 0–100 ppmOxygen (O₂)Electrochemical0–21% Vol., 0–25% Vol.Sulphur Dioxide (SO₂)Electrochemical0–20 ppmVolatile Organic Compounds (VOC)Electrochemical0–20 ppmCarbon Dioxide (CO₂)NDIR Infrared0–500 ppm to 0–100% Vol.

CO₂ configurations are available from low-ppm measurement through percentage-level measurement, including 0–500 ppm, 0–1000 ppm, 0–2000 ppm, 0–5000 ppm, 0–10,000 ppm, 0–2%, 0–5% and 0–100% volume.

Technical Specifications

Product: Dynament FGD4 Safe Area Gas Detector
Application: Fixed gas detection in non-hazardous environments
Gas types: Oxygen, toxic gases and CO₂
Sensor technology: Electrochemical / NDIR Infrared
Supply voltage: 8–24 V DC
Analogue output: 4–20 mA
Output resolution: 10 bit
Power consumption: Maximum 5 W
Internal protection: 1 A antisurge Nanofuse
Enclosure: Bayblend ABS / Polycarbonate blend
Enclosure protection: IP66
Sensor protection: IP65
Cable entry: 20 mm or ½" NPT
Dimensions: 122 × 122 × 75 mm
Detector weight: Approximately 500 g excluding weather guard
Weather guard weight: Approximately 225 g
Operating pressure: Atmospheric pressure ±10%
Typical operating temperature: -20 to +50°C, depending on sensor
Storage temperature: +10 to +20°C
Oxygen humidity: 0–95% RH, non-condensing
Toxic gas humidity: Typically 15–90% RH, non-condensing
Infrared sensor humidity: 0–95% RH, non-condensing

Specifications can vary depending on the selected gas sensor and range.

4–20 mA Gas Detection for Industrial Control Systems

The FGD4 is designed around the widely used 4–20 mA industrial analogue signal, allowing gas concentration measurements to be transmitted to a remote control or monitoring system.

The detector can be integrated with:

• PLC systems

• DCS systems

• Gas detection control panels

• Building management systems

• Industrial alarm systems

• Data acquisition systems

• Process monitoring systems

For most configurations, the FGD4 uses a 2-wire 4–20 mA current loop. The CO₂ version uses NDIR infrared sensing and requires an additional power connection.

Sensor Technology

Electrochemical Gas Sensors

Electrochemical sensors are used for gases including oxygen and various toxic gases. Depending on the selected configuration, the FGD4 can monitor gases such as:

• Oxygen

• Carbon monoxide

• Hydrogen sulphide

• Ammonia

• Chlorine

• Nitrogen dioxide

• Sulphur dioxide

• Hydrogen chloride

• Hydrogen cyanide

• Nitric oxide

NDIR Infrared CO₂ Detection

For carbon dioxide measurement, the FGD4 uses Non-Dispersive Infrared (NDIR) technology. Multiple CO₂ measurement ranges are available, from low ppm concentrations through high percentage-volume concentrations.

Calibration and Maintenance

The FGD4 provides straightforward calibration through internal ZERO and SPAN controls. Calibration can be performed using an appropriate calibration gas corresponding to the detector configuration.

An optional plug-in handheld configuration unit can also be used for detector setup and calibration with an appropriate test gas concentration.

The plug-in sensor design allows the gas sensor to be replaced without replacing the complete detector assembly, helping simplify maintenance and reduce downtime.

Typical Applications

The Dynament FGD4 can be used for fixed gas monitoring in a wide range of non-hazardous industrial and commercial environments, including:

• Water and wastewater treatment plants

• Food processing facilities

• Food storage areas

• Underground car parks

• Swimming pools

• Hospitals and medical facilities

• Boiler rooms

• Industrial utility areas

• Gas monitoring systems

• Process monitoring applications

• HVAC and ventilation monitoring

• Industrial safety monitoring

Dynament specifically identifies applications including water treatment, food processing and storage, underground car parks, swimming pools and medical facilities.

FGD4 Safe Area Gas Detector – Why Choose the FGD4?

The FGD4 combines a compact fixed detector design with flexible gas selection, multiple measurement ranges and a standard 4–20 mA output. The plug-in sensor arrangement also simplifies sensor replacement and routine maintenance.

Its 8–24 V DC supply, industrial 4–20 mA interface and range of electrochemical and infrared sensing options make it suitable for integration into existing industrial control and gas monitoring systems.

Authorized Distributor and Channel Partner in India

Trias Automation is an Authorized Distributor and Channel Partner for DwyerOmega, providing genuine instrumentation and gas detection products for industrial applications.

We can assist with:

• Gas type and measurement range selection

• Product configuration and model selection

• Technical datasheets and documentation

• Quotation and commercial support

• Application-based product selection

• Replacement sensor selection

• Technical assistance for integration

Contact Trias Automation for pricing, availability and technical assistance for the Dynament FGD4 Safe Area Gas Detector.