FGD-4400 Fixed Oxygen Deficiency Detector Zirconia Sensor Inconel Probe 0-25% Volume

FGD-4400 Fixed Oxygen Deficiency Detector

The FGD-4400 measures oxygen from 0 to 25% volume in confined spaces, inert gas blanketing systems, furnaces and flue ducts. It is intended where electrochemical oxygen cells fail: hot sample streams, high sulphur atmospheres and applications that run continuously for years without cartridge changes. The upgrade focuses on accuracy in the critical 19 to 21% band, faster response and a probe built to survive heat and corrosion.

Higher Accuracy Than Previous Generation

• Accuracy improved from plus or minus 0.3% vol to plus or minus 0.1% vol, which matters when the alarm threshold sits at 19.5% vol.
• Resolution of 0.01% vol allows detection of small oxygen ingress in nitrogen blanketed tanks.
• Zirconia measurement is inherently stable, with no electrolyte depletion and no drift from lead or acid consumption.
• Single point calibration in ambient air is sufficient, so no certified standard gas cylinder is needed on site.

Improved Detector Performance

• Response time T90 below 6 seconds, roughly four times faster than the previous electrochemical version, giving earlier warning in confined space entry.
• Heating to operating temperature in about 3 minutes, so the detector is ready soon after power up.
• Continuous self-diagnosis of heater circuit, thermocouple and electrode impedance, with a fault relay for control room visibility.
• 4-20 mA plus RS485 Modbus, with two configurable relays for alarm and fault.
• No consumable electrolyte, so maintenance is limited to periodic calibration checks rather than cell replacement.

Upgraded Materials and Construction

• Inconel 600 probe sheath replaces the 316 stainless steel sheath used previously, resisting oxidation and thermal cycling up to 700 degrees Celsius at the probe tip.
• 316L stainless steel flange and housing with graphite gasket for hot duct mounting.
• Alumina ceramic insulator and stainless protection tube prevent thermal shock cracking.
• IP66 transmitter housing placed away from the hot zone keeps electronics within their rated ambient range.

Technical Specifications

Typical Applications

• Nitrogen blanketing and inert gas systems in chemical plants
• Boiler flue gas and combustion efficiency monitoring
• Furnace and kiln atmosphere control
• Confined space entry monitoring in pits and vessels
• Cryogenic and food packaging nitrogen flush lines

Installation and Calibration

The probe mounts through a standard flange or threaded boss, with the transmitter remote mounted up to 10 m away using a shielded cable. Calibration is a single point check in ambient air, recommended every three months. A sintered filter and protection tube kit are available as spares.

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.