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The CM-420 Combustion Monitor provides a 7" touchscreen interface to monitor the oxygen percentage in a stack.

A 4-20mA output, Modbus TCP or Modbus RTU connection allows this measurement to be shared with a PLC, SCADA or building management system.

The CM-420 Combustion Monitor can be used whenever an onboard means of oxygen monitoring is required. The CM-420 Combustion Monitor is also perfect for fully metered oxygen trim applications when the 4-20mA output is connected to a PLC.

The NXCESO2 sensor used is a wide-band lambda sensor with a zirconium dioxide dual cell, with integrated heater and pump control. Probes are available in 216mm (8.5”) or 407mm (16”) insertion depths. Stack temperature is also provided by the integrated type-K thermocouple, allowing measurement up to 426°C (800°F). The sensor is self-calibrating and is designed to be maintained without having to be removed from the stack.


  • 7” touchscreen interface
  • Scalable 4-20mA output to represent oxygen
  • percentage
  • Optional 4-20mA input to measure inlet
  • air temperature, to allow for net stack
  • temperature display
  • Additional 4-20mA input for auxiliary use
  • (opacity, humidity, steam flow, etc.)
  • Digital input for initiating oxygen sensor
  • calibration
  • Four programmable relay outputs to monitor
  • oxygen, stack or auxiliary input levels
  • Modbus TCP and Modbus RTU (RS233 or
  • RS485) servers
  • IP66/NEMA4X rated
  • UL508A Enclosed Industrial Control Pane