SO-220: Fast Response Thermocouple Reference Oxygen Sensor

The SO-220 has a fast response time of 14 seconds and is designed for use in soil applications.

  • Product Name:Fast Response Thermocouple Reference Oxygen Sensor
  • Item No.:SO-220
  • Manufacturers:Apogee
  • Country of Origin:USA

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.

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