Introduction to Sensor
Output Oxygen Sensor (SO-431)
Fast, Accurate Thermal Properties in One Minute
The SO-431 Oxygen Sensor provides a fast 15-second response for measuring O₂ in soil and atmospheric applications. It includes a temperature sensor for compensation and a built-in heater to prevent condensation on the Teflon membrane. It is suitable for laboratory experiments, indoor air monitoring, compost and mine-tailings monitoring, soil redox studies, and respiration measurements.
Specifications
Specifications
| Specification | Details |
|---|---|
| Input Voltage Requirement | 5.5 to 2.4 V DC |
| Current Draw | 0.6 mA (quiescent); 1.3 mA (active) |
| Input Voltage for Heater | 12 V DC continuous |
| Input Voltage for Thermistor | 2.5 V DC excitation |
| Heater Current Draw | 6.2 mA (74 mW power requirement at 12 V DC) |
| Thermistor Current Draw | 0.1 mA DC at 70 °C (maximum, with 2.5 V DC excitation) |
| Measurement Range | 0 to 30% O₂ |
| Output | SDI-12 |
| Measurement Repeatability | Less than 0.1% of mV output at 20.95% O₂ |
| Non-linearity | Less than 1% |
| Long-term Drift | 5% signal decline per year |
| Oxygen Consumption Rate | 0.1 μmol O₂/day at 20.95% O₂ and 23 °C |
| Response Time | 15 seconds |
| Operating Environment | -20 to 60 °C; 0 to 100% relative humidity (non-condensing); 60 to 140 kPa |
| Dimensions | 32 mm diameter × 68 mm length |
| Diffusion Head Dimensions | 32 mm diameter × 35 mm length, 125 mm mesh screen |
| Flow-Through Head Dimensions | 32 mm diameter × 91 mm length, 0.25-inch barbed nylon connectors |
| Mass | 175 g (with 5 m lead wire) |
| Cable Length | 5 m |
| Gas Influence | Unaffected by CO, CO₂, NO, NO₂, H₂S, H₂, and CH₄; approximately 1% effect from NH₃, HCl, and benzene |
| SO₂ Sensitivity | Sensitive to SO₂; signal responds similarly to O₂ |
| Warranty | 4 years against defects in materials and workmanship |
Features
Special Features
01
Gaseous Oxygen Measurement
Provides reliable measurement of gaseous oxygen in laboratories, soil, compost, mine tailings, and porous media.
02
Plug-and-Play Technology
Connects the SO-431 to a ZL6 data logger for automatic sensor recognition, metadata recording, and data collection.
03
Rugged & Durable Design
The tough polypropylene housing is designed for long-term deployment in porous media, including challenging acidic environments.
04
Diffusion Head for Porous Media
The integrated diffusion head creates a small air pocket around the sensor for reliable oxygen measurement in porous media.
Applications

