OMS 420 Ex

OMS 420 Ex

O2 & COe in-situ monitoring system for use in hazardous area zone 2

The O2 and COe monitor is dedicated for continuous combustion optimisation at:

  • various industrial furnaces/ovens/boilers, with hazard of explosive atmosphere
  • petroleum refinery plants  • petrochemical plants
  • gas separation, blast furnace, coke oven or other syngas plants
  • Hazardous area designation of use: Zone 2 or Class 1, Div 2, Gr A/B/C/D
  • Special IP 65 pressurized cabinet and z-purge controller, complying to II 3G Ex pz II T3 Gc
  • Easy and fast, on site replaceable detector head with sensors (O2 & COe)
  • Integrated control unit with backlit display, operating key pad, dual galvanic isolated 4 … 20 mA output and digital output RS 485 (Modbus RTU)
  • Stainless steel SS316Ti flange 4″ ANSI-150Ibs with flow guidance probe tubes, from 11.81“ up to 78.81“ length
  • Unique hot solid electrolyte sensor for combustible COe-measurement without need for sample dilution with air as required for catalytic bead sensors (Pellistors) (Option)
  • Unique blow-back system for dusty flue gases (Option)
  • Integrated auto-calibration for accurate measurements (Option)
  • Dust tight and water proof enclosure, with optional ATEX heater for very low ambient air temperatures or optional ATEX Vortec cooler for high ambient temperatures
O2 0 … 25 % (zirconium dioxide)
COe 0 … 1,000 ppm (hot solid electrolyte)
Temperature up to 1,832°F (1,000 ° C)
Pressure 361 inH2O to 441 inH2O (900 to 1.100 mbar)
Flow Velocity min. 1 m/sec to max. 30 m/sec


Warm up time minimum 30 minutes
Ex classification Ex II 3G Ex pz II T3 Gc
Response time < 10 seconds
Flange flange 4″ ANSI-150 lbs, stainless steel 1.316Ti
Probe tube length 11.81″ to 78.81″ (300 mm to 2,000 mm), Inconel steel
Interfaces Dual, analog output 4 … 20 mA, isolated, max. load 500R, RS 485
digital interface (Modbus RTU), DIN-rail RS 485/Profibus converter
Calibration manual or automatic (user free settable)
1 point (offset) or 2 points (offset and span)
Power supply 100…240 Vac / 47…63 Hz / 100 W or 300 W with cabinet heater
Compressed air 87 … 116 psi (6…8 bar), free of dust, oil and water (DP -4°F (-20°C) or less)
Ambient conditions 41°F … 113°F (+5 °C … +45 °C) (149°F (+65 °C) with ATEX Vortec cooler)
-49°F … 113°F (-45°C … +45 °C) with cabinet heater
Dimensions 25.58″ x 19.68″ x 13.77″ (650 x 500 x 350 mm) (H x W x D)
Protection IP 65
Weight 55lbs. (25 kg)

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