Tech Note 439 Detail

Oxygen Gas Sensor Theory & Care

Affected Products:

PS-2126 PASPORT Oxygen Gas Sensor
CI-6562 Oxygen Gas Sensor

Problem/Symptom:
Oxygen Gas Sensor Theory & Care

PASCO Solution:

Theory of Operation

The oxygen probe is a galvanic fuel cell with a gas-permeable Teflon membrane at one end. Any gas that is in contact with the sensor membrane will diffuse through the membrane and dissolve in a thin layer of weak acetic acid gel electrolyte. Oxygen reduces at the gold cathode and lead oxydizes at the anode.

At the cathode:

O2 + 2H2O + 4e- => 4 OH-

At the anode:

2Pb + 4OH- => 2 PbO + 2H2O + 4e-

The flow of electrons from the anode to the sensing cathode via an external electronic circuit is directly proportional to the amount of oxygen in the gas phase and varies linearly with the partial pressure of the oxygen in the gas stream. The electrolyte conducts the ionic current, generated by the migrating OH- groups.

Specifications (Max 250)

  • Range: 0-100% Oxygen
  • Response 90%: 15 s (23 °C)
  • Humidity: 5 -95% (non-condensing)
  • Temperature Dependence: < 3% from 15 - 40 C
  • Stability: 1% over 8 hours of full scale at constant temperature, pressure and humidity
  • Expected Life: 3-5 years @ 20.9 % oxygen (900,000 Oxygen% hours)
  • Manufacturer Warranty: 2 years
  • Interferences: < 2% of full scale for the following concentrations of gases
    • 5% Halothane
    • 5% Isoflurane
    • 5% Enflurane
    • 6% Sevoflurane
    • 10% CO2
    • 15% Desflurane
    • 70% Helium
    • 75% Nitrous Oxide

Specifications (Obsolete Analytical Industries Probe)

  • Range: 0-100% Oxygen
  • Expected Life: 24 - 42 months (electrolyte attacked by by acidic gases (CO2, SO2, H2S, etc.) )
  • Response 90%: 6 sec
  • Signal Output: 8.5-13 mV
  • Manufacturer Warranty: 12 months

Storage

  • Place the red oxygen-restricting tape over the oxygen sensor.
  • Store at room temperature or in the refrigerator (not freezer) with the sensing surface pointed down. (Optimal storage temperature is 5 - 25 C. Maximum storage temperature -15 C to 50 C.)

Creation Date: 09/12/2003
Last Modified: 10/2/2003
Mod Summary: