- Dissolved oxygen probe
- Membrane-covered polarographic Clark probe
- Built-in temperature sensor
- PVC body <-> more rugged in use
- Ideal for measurements in the laboratory, in the field or in industry
- Small diameter (only 12 mm),
- Used for measurements in small samples (e.g. beakers in laboratories)
Dissolved oxygen probes comprise two precious-metal electrodes separated
by an electrolyte. Thus, the BOT4
probe has a platinum cathode soldered
in glass and a silver anode. These
two electrodes are immersed in a saline
electrolytic solution (surfactant
KCl). The probe is equipped with a
membrane (PTFE film) which is permeable to oxygen.This membrane separates the
electrodes and the saline electrolyte from the measurement environment. The
oxygen diffuses through the membrane until it reaches the electrolyte where it
is measured in dissolved form. The quantity of oxygen is proportional to the
solution partial pressure.
The measurement itself is performed by applying a potential between the two electrodes. On the cathode, the following reduction occurs:
+ 2H2O + 4e- ↔ 4OH-
While oxidization takes place on the anode:
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 of
sulphite-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 is
then possible to adjust the slope
either by placing the probe in ambient air and adjusting the value to 100%, or by immersing the probe in
water 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
water in mg/L at a given pressure and temperature). The type of calibration will be chosen according to the medium (gas or
liquid) in which the measurements will be performed.
The temperature and pressure
significantly influence the concentration of dissolved oxygen. This means it is
important to work at constant
temperature and pressure.
- Temperature compensation allowing work at temperatures between 25 and 35°C
- Faster response time 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.