Posted in | Oxygen Sensors

Zirconia Oxygen Sensor System with a Temperature Range of -100 °C – 250 °C

The Zirconia Oxygen Sensor System offers a complete solution, preventing the need for customers to produce their own electronics. This sensor system is regularly used in combustion control systems, burning coal, gas, oil and biomass and in oxygen generation systems.

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

Because of its innovative design, this system does not require a reference gas, and it uses a well-established zirconium dioxide element at its heart. This, along with its rugged stainless steel construction points out that the sensor can be used in aggressive environments and extreme temperatures.

A unique closed loop measurement system is used by these oxygen sensors. A heartbeat signal is also generated as the sensor continuously measures the oxygen level, and this signal provides an instant warning of any failures.

The sensor is housed in a short probe with an M18x1.5 mm thread, bringing about effortless and quick installation. The oxygen sensor is capable of working in temperatures ranging from -100 °C to 250 °C and has a lifetime of up to 10 years (based on the application).

The zirconia oxygen sensor measures oxygen concentrations of 0.1% to 25% and 0.1% to 100% when it is connected to the OXY-LC interface board.

Part Numbering Guide


Technical Specifications

Supply voltage  
  R485 output variant 8-28Vdc
  Analogue output variants 20-28Vdc
Supply Current 600 mA max. at 24Vdc
1.2A max. at 12 Vdc
Digital Output RS485 (Modbus RTU)
Analogue Output 4-20 mA; load 600 Ω max
or 0-10 V; load 10 kΩ min
Pump impedance at 700 °C¹ <6 kΩ
Permissible gas temperature -100 to 250 °C
Gas flow rate² 0-10 m/s
Operating pressure limits³ 260-1260 mbar absolute
Mounting thread M18x1.5

¹ The constant current source used in the pump circuit should be designed to drive a load of up to 6kΩ.
² With 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.
³ Sensor and interface for correct barometric pressure compensation.

Outline Drawings

Sensor Layout

Interface Board Layout

Output Values

Oxygen range (analogue output) 0.1-25% O2
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 <4s
Initial warm up time (until stable output) 5-10 mins
Output inactive start up delay (heater warm up):  
  From OFF to ON mode: 60 s
  From standby to ON mode (RS485 only): 20 s


Electrical Interface

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


Features and Benefits


The key features of the Zirconia Oxygen Sensor System are as follows:

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


The main benefits of the Zirconia Oxygen Sensor System are as follows:

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

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