The SO-220 has a fast response time of 14 seconds and is designed for use in soil applications. It comes with a thermocouple wire to correct for temperature changes and a restive heater to raise the temperature of the membrane approximately two degrees above ambient temperature to keep condensation from occurring on the Teflon membrane and blocking the diffusion path of the sensor. Typical applications include measurement of O2 in laboratory experiments, monitoring gaseous O2 in indoor environments for climate control, monitoring of O2 levels in compost piles and mine sailings, monitoring redox potential in soils, and determination of respiration rates through measurement of O2 consumption in sealed chambers or measurement of O2 gradients in soil/porous media.
Soil Oxygen Concentration
Quasi-continuous measurements of bulk soil oxygen concentration in managed and natural ecosystems.
Measurement Range 0 to 100 % O2 Sensitivity (at sea level, 101.3 kPa) 12-13 mV in 21 % O2, 0.6 mV per % O2, 6 µV per 0.01 % O2 Response Time (time required to read 90 % of saturated response) 14 seconds Output at 0 % O2 2 % of output at 20.95 % O2 or 0.2 ± 0.1 mV Measurement Repeatability Less than 0.1 % of mV output at 20.95 % O2 Non-linearity Less than 1 % Signal Decrease per Year 6.3 % per year (0.8 mV per year) Oxygen Consumption Rate 2.2 µmol O2 per day at 20.95 % O2 and 23 C Operating Environment -20 to 60 C, 0 to 100 % relative humidity (non-condensing), 60 to 140 kPa Input Voltage Requirement 12 V DC continuous (for heater), 2.5 V DC excitation (for thermistor Heater Current Drain 6.2 mA (74 mW power requirement when powered with 12 V DC source) Thermistor Current Drain 0.1 mA DC at 70 C (maximum, assuming input excitation of 2.5 V DC) Dimensions 32 mm diameter, 68 mm length Mass 175 g (with 5 m of lead wire) Cable 5 m of six conductor, shielded, twisted-pair wire Warranty 4 years against defects in materials and workmanship