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Flue Gas Probes

General Information

ZIROX flue gas probes (SS28/SS31) are robust sensors which serve the λ-determination in large-scale firing plants as well as the measurement of oxygen partial pressure of furnace atmosphere.
The probes are calibration-, drift- and maintenance-free. During measurements in reducing atmosphere, a falsification of the gas composition caused by cooling of the measuring gas in a suction line does not occur. An integrated heater provides the working temperature. The use of high-quality components and materials guarantees high long-term stability.

Depending on the application, an SS28 (normal flue gas measurements, ) or an SS31 (reducing conditions or high gas velocity) is used.


  • Flue gas measurements in power plants
    (TÜV-Approval according to "TA Luft, 13. und 17. BImSchV", Federal Immission Control Ordinance)
  • Process gas measurements

Technical Data Oxygen Probe SS28H/SS31H

Length300...1800 mm
Diameter25 mm
Weight1...3.5 kg
Dimension clamp head75 x 80 x 60 mm
Clamps5 x Phönix MBK 2,5/E
Protection degreeIP52, IP65 on request
Power supply
24 V (DC oder AC)36 V (DC oder AC)
Heater resistance AC / DC
5 Ohm8 Ohm
Heating current AC / DC
5 A4.5 A
Heating power AC / DC
115 VA160 VA
Heater controlmax. cycle time at PWM 500 ms
Range-0.01...20.6 Vol.-% O2
Accuracy< 5 % rel. error
Working temperature700...800 °C


-2 m...-10 mV

Sensor voltage
(5.0 Vol.-%, 800 °C)
-33.1 mV
Thermocoupletype B (800 °C corresponds to 3.2 mV)
Flow measuring gasmax. 10 m/s
Reference gasambient air
Flow reference gas5...10 l/h
Clamp assignment:
(1) GroundAGND
(2) Sensor voltage-Uz
(3) Thermal voltage+Ut
(4) HeatingUH
(5) HeatingUH

Mounting recommendation:

  • stuffing box or cutting ring fitting


  • Test gas channel (for in-situ check of the probe)
  • Immersion sleeve (probe protection at gas flow > 10 m/s)


Note: You are not sure which device is required for your application?
Please complete our questionnaire and send it to infoziroxde.