Data Sheet

Operating principle

A galvanic dissolved oxygen probe consists of a Polytetrauoroethylene membrane, an

anode bathed in an electrolyte and a cathode. Oxygen molecules defuse through the

probes membrane at a constant rate (without the membrane the reaction happens to

quickly). Once the oxygen molecules have crossed the membrane they are reduced

at the cathode and a small voltage is produced. If no oxygen molecules are present, the

probe will output 0 mV. As the oxygen increases so does the mV output from the probe.

Each probe will output a different voltage in the presence of oxygen. The only thing that

is constant is that 0mV = 0 Oxygen. (A galvanic dissolved oxygen probe can also be used

to detect the Oxygen content in gases).

The Atlas Scientic

™

EZO

™

Dissolved Oxygen circuit works with:

Slow response, requires external power, expensive.

Requires external power, output in μA.

Requires no external power, output in mV.

Optical probe

Polar Graphic probe

Galvanic probe

Electrolyte

Cathode (Pure silver rod)

Membrane

Anode (Zinc)

Flow Dependence

Time (sec)

90%

60%

5 10 15 20 25 300

Dissolved Oxygen

Stagnant water

Oxygen being

consumed by probe

20%

One of the drawbacks from using a galvanic

probe is that it consumes a VERY small amount

of the oxygen it reads. Therefore, a small amount

of water movement is necessary to take accurate

readings. Approximately 60 ml/min.