- Dissolved oxygen probe
- Membrane-covered polarographic Clark probe
- PVC body <-> more rugged in use
- Varied use: in the laboratory, in the field or in industry
Dissolved oxygen probes comprise two precious-metal electrodes separatedby an electrolyte. Thus, the BO23 probehas a platinum cathode soldered inglass and a silver anode. These twoelectrodes are immersed in a salineelectrolytic solution (surfactantKCl). The probe is equipped with amembrane (PTFE film) which is permeable to oxygen.This membrane separates theelectrodes and the saline electrolyte from the measurement environment. Theoxygen diffuses through the membrane until it reaches the electrolyte where itis measured in dissolved form. The quantity of oxygen is proportional to the solutionpartial pressure.
The measurement itself is performed by applyinga potential between the two electrodes. On the cathode, the following reductionoccurs:
O2 + 2H2O + 4e- ↔ 4OH-
While oxidization takes place on the anode:
4Ag + Cl- ↔ 4AgCl + 4e-
The current produced is directly proportional to the dissolved oxygen concentration.
Calibration of the oxygen probe usually involves two phases. First, the probe is immersed in a solution ofsulphite-enriched water in which the oxygen content is 0 mg/L. This allows you to adjust the instrument's offset. The probe is then rinsed. It isthen possible to adjust the slope eitherby placing the probe in ambient air and adjusting the value to 100%, or by immersing the probe inwater with strong agitation and adjusting the value, this time expressed in mg/L,according to Mortimer's table (which defines the solubility of oxygen in waterin mg/L at a given pressure and temperature). The type of calibration will be chosen according to the medium (gas orliquid) in which the measurements will be performed.
The temperature and pressuresignificantly influence the concentration of dissolved oxygen. This means it isimportant to work at constanttemperature and pressure.
- Faster response time than an optical sensor
- Consumes less energy than an optical sensor
- 5-pole DIN plug for adaptation to your instruments.
For further technical details, please read the sales brochure on the electrodes and/or contact us.