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Zirconia Oxygen Sensor System

The Zirconia Oxygen Sensor System offers a complete solution, removing the need for customers to develop their own electronics. Frequently used in combustion control systems, burning coal, oil, gas and biomass and in oxygen generation systems.

The Zirconia Oxygen Sensor System consists of SST’s fast response (<4s T90) zirconium dioxide (ZrO₂) screw fit sensor in conjunction with the OXY-LC oxygen sensor interface board.

The system employs a well proven, zirconium dioxide element at its heart and, due to its innovative design, does not require a reference gas. This, along with its rugged stainless steel construction means the sensor can be used in extreme temperatures and aggressive environments.

These oxygen sensors use a unique closed loop measurement system. While the sensor continuously measures the oxygen level, a heartbeat signal is also generated, providing an immediate warning of any failures.

The sensor is housed in a short probe with an M18x1.5mm thread, making installation quick and easy. The oxygen sensor can operate in temperatures ranging from -100°C to 250°C and has a lifetime of up to 10 years (depending on the application).

When connected to the OXY-LC interface board, the zirconia oxygen sensor can measure oxygen concentrations of 0.1% to 25% and 0.1% to 100%.

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Part Numbering Guide


Supply voltage
    R485 output variant 8-28Vdc
    Analogue output variants 20-28Vdc
Supply Current 600mA max. at 24Vdc
1.2A max. at 12Vdc
Digital Output RS485 (Modbus RTU)
Analogue Output 4-20mA; load 600Ω max
or 0-10V; load 10kΩ min
Pump impedance at 700⁰C¹
Permissible gas temperature -100 to 250⁰C
Gas flow rate² 0-10m/s
Operating pressure limits³ 260-1260mbar absolute
Mounting thread M18x1.5


Oxygen range (analogue output) 0.1-25% O₂ br>
or 0.1-100% O₂
Oxygen range (Modbus RTU) 0.1-100%
Accuracy after calibration 0.5% O₂
Output resolution 0.01% O₂
Response time
Initial warm up time (until stable output) 5-10 mins
Output inactive start up delay (heater warm up):
    From OFF to ON mode: 60s
    From standby to ON mode (RS485 only): 20s


Sensor Layout


Interface Board Layout


¹The constant current source used in the pump circuit should be designed to drive a load of up to 6kΩ.
²With baffle fitted to shield the sensor from direct cooling and pollution by the flue gas; refer to Screwfit Zirconia Oxygen Sensor Datasheet for fitment details.
³Sensor and interface for correct barometric pressure compensation.



Pin RS485 Analogue
1 Sensor heater + (1) Sensor heater + (1)
2 Sensor heater 0Vdc (2) Sensor heater 0Vdc (2)
3 Sensor pump Sensor pump
4 Sensor common Sensor common
5 Sensor sense Sensor sense
6 8-28Vdc 20-28Vdc
7 0Vdc 0Vdc
8 RS485 A (+) 4-20mA or 0-10Vdc
9 RS485 B (-) Calibrate IN/PWM OUT


  • Zirconium dioxide technology
  • Interface electronics included
  • Integral heating element
  • Variety of probe mounting positions available; 28mm, 45mm & 55mm
  • M18x1.5 screw mounting
  • All stainless steel construction both internally and externally


  • Long life
  • No reference gas required creating the ability to measure a wide oxygen range
  • Non-depleting technology
  • Linear output signal
  • No need for temperature stabilisation
  • Can be used in high pressure and temperature environments
  • Simple recalibration if/when required
  • Full technical and application support available
  • This field is for validation purposes and should be left unchanged.