FGD-4100 Explosion Proof Fixed Combustible Gas Detector 316L Housing 100%LEL Catalytic Sensor

FGD-4100 Explosion Proof Fixed Combustible Gas Detector

The FGD-4100 is a fixed combustible gas detector for continuous 0-100% LEL monitoring in process areas, tank farms, compressor rooms and boiler houses. The upgrade was driven by three complaints about earlier catalytic detectors: readings that slid between calibrations, slow response in confined spaces, and aluminium housings that corroded in coastal and chemical plant atmospheres.

Higher Accuracy Than Previous Generation

• Accuracy improved from plus or minus 5% FS to plus or minus 2% FS through a matched catalytic bead pair and a temperature compensated bridge circuit.
• Zero drift held below 1% FS per month, which keeps the detector inside alarm set points without weekly zero adjustment.
• Built-in temperature compensation across -40 to 70 degrees Celsius prevents the low reading bias that catalytic sensors show in cold weather.
• Sensor poison resistance against silicone vapour and sulphide compounds is improved, protecting accuracy in areas where general purpose catalytic beads lose sensitivity.

Improved Detector Performance

• Response time improved from 25 seconds to T90 below 10 seconds, giving faster alarm initiation in enclosed spaces.
• Non intrusive magnetic key calibration, so the housing stays sealed during routine bump tests and calibration.
• OLED display showing live concentration, sensor life and fault codes, which shortens troubleshooting to a single site visit.
• 4-20 mA output with two alarm relays and optional RS485 Modbus, allowing direct connection to gas controllers, PLC and SCADA.
• Dedicated fault relay distinguishes a genuine fault from a gas alarm, avoiding unnecessary plant shutdowns.

Upgraded Materials and Construction

• 316L stainless steel housing replaces the previous die cast aluminium body, giving full resistance to salt spray, hydrogen sulphide and acidic process atmospheres.
• Stainless steel sensor housing and sintered flame arrestor resist clogging from dust and oil mist, keeping response time stable over the service life.
• IP66 sealing with two M20 cable entries keeps moisture out during washdown and monsoon conditions.
• Marine grade mounting bracket and stainless fasteners prevent the galvanic corrosion that seizes aluminium brackets after one season outdoors.

Technical Specifications

Typical Applications

• Oil and gas tank farms, loading gantries and pump stations
• Natural gas pressure regulating stations and boiler rooms
• Chemical and petrochemical process areas
• Wastewater treatment digester and sludge areas
• Coastal terminals and marine engine rooms

Calibration and Maintenance

Sensor cartridges are field replaceable without removing the housing from the bracket. A calibration cup, flow regulator and gas cylinders are available as an accessory kit. Recommended bump test interval is one month, with full calibration every six months in clean service and every three months in dirty or poisoned service.

Ordering and Support

Each detector is supplied with a calibration certificate, sensor cartridge, weatherproof sunshade, mounting bracket and operation manual. Optional items include a calibration cup, duct mounting kit, remote display and HART or Modbus gateway. Our technical team supports configuration, bump testing schedules and spare sensor supply.

Contact our sales team for a quotation, datasheet or sample evaluation unit.