THERMOX Model WDG-V Combustion Analyzer

The reliable identification of low combustion oxygen in a fired heater or boiler has always been critical to the effectiveness of the Burner Management System for proper control and safety.


Prevention is so Easy… Living Through a Disaster Isn’t

The reliable identification of low combustion oxygen in a fired heater or boiler has always been critical to the effectiveness of the Burner Management System for proper control and safety.

Low emission burners and aggressive firing control points to achieve increased efficiency and emission reductions have driven the industry to tighter control measures. But tighter control measures also hold a greater potential for combustion events. Reducing the risk of a combustion event has become a priority and has led to the implementation of Safety Instrumented Systems (SIS). This additional layer of safety is added to the Basic Process Control System.

The Model WDG-V Combustion Analyzer has been designed to provide an additional layer of safety with the measurement of excess O2, Combustibles and Methane and by using these measurements to ensure the safe operation of the Burner Management System.


  • Precise control of low O2 setpoints with confidence
  • CO detection for control interlocks and safety shutdown
  • Predictive diagnostics
  • SIL 2 Capable for SIS implementation of IEC 16508/61511

AMEVision Display Unit

The AMEVision Display Unit enables the convenience of site calibration and communication with the analyzer via MODBUS RTU, TCP/IP Fast Ethernet via RJ45, USB port, and 4.2″ VGA display.


  • End of life prediction of cell and combustibles detectors
  • Stability Indicator during the calibration process
  • Trend data logging
  • Cell enclosure and electronics temperature monitoring



Principle of Operation (O2) Zirconium oxide for net oxygen measurement and dual hot-wire catalytic detectors for both combustibles and methane.
Output Range (O2) Oxygen: From 0-1 to 0-100%
Combustibles: 0-1000 PPM with Overrange 0-2,000 PPM to 0-10,000 PPM, 0-2 to 0-5%
Hydrocarbon: 0-5%
Accuracy (O2) ±0.75% of measured value or ±0.05%, whichever is greater
Combustibles: ±2% of full scale output range
Hydrocarbon: ±5% of full scale output range
Response Oxygen: 90% of a step change < 11 seconds with Flame Arrestors
Combustibles & Hydrocarbon: 90% of a step change < 20 seconds with Flame Arrestors
Aspirator Air Requirements 3 SCFH Typical at 3 to 6 psig, Instrument air or Nitrogen
Analog Output Three isolated linear current outputs for O2, combustibles and hydrocarbon. Each output can be 4-20 mA, 0-20 mA, 20-4 mA or 20-0 mA and is fully scalable. NAMUR Configurable. Hold or track during calibration. Max. load 1200 Ω
Alarms Set relays to energize or de-energize on alarm
Contact Rating 0.5A, 30V, 10VA max. non-inductive load, AC or DC
Digital Communication 2 wire MODBUS RTU, 57.6 KBaud
Configuration MODBUS RTU, AMETEK configuration software, or AMEVision HMI
Diagnostics Low Sample Flow, Cell & Detector age tracking, Cell resistance, Calibration required, Analog current verification
Calibration Calibrate or verify calibration. Stored calibration and verification data. Selectable calibration gas run time and process recovery time. Timed automatic calibration with optional Remote Calibration Unit.
Sample Pressure ±6 in. water gauge
Max. Sample Dewpoint 392°F (200°C)
Max. Flue Gas Temp. / Probe Type / Lengths 1300°F (704°C) / 316 SS / 36” – 108”(91 cm – 274 cm)
1875°F (1024°C) / 310 SS / 36” – 108”(91 cm – 274 cm)
3000°F (1648°C) / Hexoloy® / 24” – 72” (60 cm – 182 cm)
Environment Ambient Temp.: -25°C to 65°C
Relative Humidity: 5% to 95%, non-condensing
Enclosure Hinged IP65 (NEMA 4X), weather resistant, stainless steel, explosion-proof, purged, and floor mount versions available.
UL Class I, Div II, Gp B, C, D or ATEX Zone 2, T3 with Purge
Power Requirements 115 VAC, ±10%, 47-63 Hz, 740 VA max.; 230 VAC, ±10%, 47-63 Hz, 740 VA max.
Calibration Gas Requirements Use calibration gases @ 10 psig, 1.5 SCFH (0.7 L/min.)

O2 Span Gas: Air or from 1.0% to 100% O2, balance N2
O2, Comb. & CH4 Zero Gases: From 0.1 to 10% O2, balance N2
Comb. Span Gas: 60 to 80% (PPM ranges) or 40% to 60% (% ranges) of the selected comb. recorder output range in certified equal mixtures of CO + H2, 3-4% O2, balance N2
Hydrocarbon Span Gas: 2% CH4, 8% to 10% O2, balance N2