Oxygen Measurement Applications
- Oxygen measurements in protective gases
- Exhaust gas measurements in large-scale engines
- Control optimization in small combustion plants
- Furnace gas measurements in heat treatment equipment
- Optimization of incineration plants
- Monitoring of industrial processes under protective or inert gas atmosphere
Technical Data Miniature Probe SS27/MS27
| Installation length |
65 mm (incl. M18x1.5), 75 mm (DN40KF) |
| Diameter |
10 mm |
| Weight |
0.5 kg |
| Dimension clamp head |
64 x 58 x 36 mm |
| Protection degree |
IP42, others on request |
| Power supply |
24 V DC |
| Power consumption |
17 W |
| Warm-up |
approx. 5 min |
| Sensor voltage (raw signal) |
0…200 mV (0…300 mV on request) |
| Range (SS27) |
15 ppm…20.6 Vol.-% O2 (0…200 mV) 0.13ppm…20.6 Vol.-% (0…300 mV) |
| Accuracy |
< 5 % rel. error |
| Measuring gas temperature |
max. 300 °C |
| Probe working temperature |
700 °C |
| Surrounding conditions probe head |
max. 50 °C, rel. humidity < 80 % |
| Offset |
approx. -2…-8 mV (compensable) |
| Output signal |
4-20 mA (0-5 V, 0-10 V on request) |
Plug Assignments
| (1) Analog output |
+ IA |
| (2) Analog output |
GND IA |
| (3) Power supply |
GND VB |
| (4) Power supply |
+ 24 V VB |
| (5) Relay |
RDY |
Calculation of Oxygen Concentration
The oxygen partial pressure is calculated by the
NERNST equation.
ϕ(O₂) = 20.64 * e^(-46.42 U/T)
- ϕ(O₂): oxygen concentration in Vol.-%
- U: cell voltage in mV
- T: cell temperature in K (700 °C = 973.15 K)
- 20.64: oxygen concentration in ambient air at 50% relative humidity
Translation of the Output Signal (Range 0…200mV)
| Current output 4-20 mA |
1 mA ≙ 12.5 mV cell voltage |
| Voltage output 0-5 V |
1 V ≙ 40 mV cell voltage |
| Voltage output 0-10 V |
1 V ≙ 20 mV cell voltage |
Example for 0…200 mV range:
At a current of 5.5 mA ((5.5-4)mA × 12.5 mV = 18.75 mV) an oxygen concentration ϕ(O₂) = 8.43 Vol.-% results.
.