Model WDG-IV Series Analyzers

The THERMOX Model WDG-IV analyzers measure oxygen, combustibles and methane in natural gas-fired applications.


The THERMOX Model WDG-IV analyzers measure oxygen, combustibles and methane in natural gas-fired applications. They are ideal for gas-fired power boilers or for boilers using natural gas during start-up and shutdown. With these analyzers, you can monitor oxygen and combustibles for maximum fuel efficiency. Available with Series 2000 controller. This analyzer has a close-coupled extractive design for fast response in a wide range of flue gas applications up to 3000°F (1648°C).


  • Weatherproof, stainless steel sensor enclosure
  • Zirconium oxide oxygen cell
  • Catalytic Combustibles detector for 0-2000 ppm
  • Catalytic Methane detector for 0-5%
  • Class I, Div. 2 or Class I, Div. 1 option
  • Two isolated current outputs
  • Four alarms
  • Diagnostics
  • RS-485
  • HART option available
  • UL Listed


WDG-IV Series Combustion Analyzers
Principle of Operation (O2) Zirconium oxide for net oxygen measurement and dual catalytic detectors for both combustibles and methane.
Output Range (O2) Oxygen: From 0-1 to 0-100%
Accuracy (O2) ±0.75% of measured value or ±0.05%, whichever is greater
Combustibles: ±2% of full scale output range
Response Oxygen: 90% of a step change < 30 seconds
Aspirator Air Requirements 10-20 SCFH (4.7 to 9.4 L/min) Typical at 15 to 100 psig
Analog Output Two 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 Two independent oxygen alarms each high or low selectable
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 Watchdog timer and service alarms. Twenty-entry event log.
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 ±10 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.: -20°C to 71°C
Relative Humidity: 10% to 90%, non-condensing
Enclosure Lift-off NEMA 3R, weather resistant, stainless steel.
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, 1.53 SCFH (0.7 L/min.)

O2 Span Gas: Air or from 1.0% to 100% O2, balance N2
O2 Zero Gas: 2% or from 1.0% to 10% O2, balance N2


WDG-IV flue gas oxygen analyzer
WDG-IVC / 0 TO 500 PPM