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General Information

The main part of the Q-probe SS20 is a potentiometric solid electrolyte cell (zirconia sensor). Because of several oxygen concentrations at the electrodes (ambient air at reference electrode), a voltage is reached which is proportional to the logarithm of the oxygen concentrations. The designation Q-probe points out that the quotient of partial pressures of the reactive furnace gases (only gases reacting with oxygen) can be calculated from the probe signal. Water vapour and hydrogen or H2O+CO2 and H2+CO in the water gas equilibrium shall serve as an example. The Q-probe is calibration-, drift- and maintenance-free. Falsifications of the gas composition do not occur. In suction lines, however, the cooling of the measuring gas may cause them. The use of high-quality components and materials guarantees high long-term stability.


The Q-probe serves the monitoring of protective gases or the controlling of partial oxidation processes (redox-quotient, oxidation character KO) in heat treatment applications for metallic materials. The probe is also used in nitriding or nitrocarburizing applications. By combining the signals of a Q-probe and a QE-probe, the nitriding character KN or carburizing character KC can be adjusted and controlled as well as, if necessary, the carburizing character Kc considering the unburnt gas compound.

Technical Data Q-Probe SS20.BQ

Length300...1800 mm
Diameter25 mm
Weight1...3.5 kg
Dimensions clamp head75 x 80 x 60 mm
Clamps3 x Phönix MBK 2.5/E
Protection degreeIP52, IP 65 on request
Range0...1500 mV
Accuracy< 5 % rel. error
Working temperature500...1100 °C
Thermocoupletype B
(800 °C corresponds to 3.2 mV)
Reference gasambient air
Reference gas flow5...10 l/h
Clamp assignment: 
(1) GroundAGND
(2) Sensor voltage-Vz
(3) Thermal voltage+Vt


Mounting recommendation:


  • stuffing box or cutting ring fitting


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