WDG-V Blowback

THERMOX Model  WDG-V Combustion Analyzer

The WDG-V Blowback offers a complete solution for combustion process control and safety in coal fired power boilers and high particulate applications. Its direct-mounted, close-coupled extractive design allows for fast continuous measurement of oxygen (O2), combustibles (CO+H2) and methane (CH4), and the Blowback option efficiently cleans the sample probe and filter from an integrated enclosure.

The WDG-V Blowback is designed with measurement redundancy and onboard diagnostics that assess the health of the analyzer and validate the proper combustion measurements, providing low probability of undetected analyzer faults. Communication through Modbus RTU or Fast Ethernet enables remote communication for diagnostics, calibration, verification, error notification and remote performance monitoring for maintenance LANs or asset management systems (AMS).

The Blowback option also prevents condensation within the sample line by preheating the air prior to blowback.  Blow back can be automated or manually triggered via an existing AMEVision, and maintenance can be performed on the analyzer without removing it from the process flange.

  • Integral unit with single air and power connections with no heated sample line required
  • Heated accumulator to prevent condensation during blow back
  • Configurable blow back automation for regular time intervals or low flow levels
  • Predictive diagnostics with proactive alarms, data management and digital communications
  • Measurements of O2, Combustibles and Hydrocarbon in one unit
  • Specifications +

    Principle of operation (O2) Zirconium oxide for net oxygen measurement and catalytic detectors for both combustibles and methane           
    Output range (O2) Oxygen: From 0-1% to 0-100%

    Combustibles: From 0-2,000 ppm to 0-10,000 ppm or from 0-1% to 0-5%
    Methane: 0-5%

    Accuracy (O2)

    Oxygen: ±0.75% of measured value or ±0.05%, whichever is greater
    Combustibles: ±2% of full scale output range
    Methane: ±5% of full scale output range

    Response Oxygen: 90% of a step change in <6 seconds (using calibration gas)
    Combustibles & Methane: 90% of a step change in <20 seconds (using calibration gas)    
    Drift  <0.1% of cell output per month; <0.005% O2 per month with 2% O2 applied
    Aspirator air requirements

    ≈ 3 scfh (1.4 L/min) at 80 to 100 psig (5.63 to 7.04 kg/cm2)

    Max. flue gas temperature/

    probe type / lengths

    704°C (1300°F) / 316 SS / 910 to 2440 mm (36 to 96in.)

    1024°C (1875°F) / 310 SS / 910 to 2440 mm (36 to 96in.)

    Max. sample dewpoint 150°F (300°C)

    Five dry contact alarms. One service alarm, one data valid alarm. Remaining alarms can be set to oxygen, combustibles, and methane

    Contact rating

    0.5 A, 30V max., non-inductive load, DC or AC 10W max

    Diagnostics  Watchdog timer and service alarm (trouble alarm). Cell resistance measurement. Individual I/O control. Cell/detector end-of-life warning

    RS-485, 2 wire Modbus RTU Interface (57.6 KBaud)

    Analog output 

    Three isolated linear current outputs for O2, combustibles, methane. 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 

    Sample pressure  ±10 in. water gauge 
    Flow sensor 

    Blocked flow sensor for measuring flow in the sample loop. Alarm set to 45% of nominal flow 

    Sensor enclosure 

    Hinged IP65 (NEMA 4X), weather-resistant, stainless steel. Floor-mount versions also available

    Environment  Ambient temperature: -25° to 65°C (-13 to 149°F)

    Relative humidity: 10 to 90%, non-condensing

    Power requirements

    115 VAC, ±10%, 47 to 63 Hz, 950 VA max
    230 VAC, ±10%, 47 to 63 Hz, 950 VA max 


    Calibrate or verify calibration. Store last 10 calibration data. Selectable calibration gas run time and process recovery time. Timed automatic calibration with optional remote calibration unit

    Calibration gas requirements

    Use calibration gases @ 10 psig, 3.0 SCFH. Use certified mixtures only
    O2 span gas: Instrument air or from 1.0 to 100% O2, balance N2 (typically, 2% O2, balance N2)
    O2 and combustibles zero gas: 2% O2 or from 0.1 to 10% O2, balance N2
    Combustibles span gas (WDG-VC and WDG-VCM only): 60 to 80% of the selected combustibles recorder output range in equal mixtures of CO + H2, 3 to 4% O2, balance N2
    CH4 span gas (WDG-VM, WDG-VCM only): 2% CH4, 8 to 10% O2, balance N2
    For example, using a 2000 ppm combustibles range, span with a mix of 800 ppm CO, 800 ppm H2, 3 to 4% O2, balance N2

    Remote calibration unit (RCU)  Requires a separate air line for Blowback
    Probe  Max. probe length of 6 to 8 feet

    Filter options are dependent upon probe length and particulate loading of application

    System compliance 

    EMC compliance: 2014/30/EU
    Safety compliance (LVD): 2014/35/EU
    Designed for general purpose

  • Documents +

  • Certifications +

    Designed for general purpose environments