4220 Flow Meter
Section 5 Options and Accessories
5-22
probe. Use only 2-mil membranes with D.O. probes
connected to Isco flow meters.
Figure 5-6 D.O. Parameter Module
You must use the Isco 270 D.O. Module box between the probe
and flow meter; this extends the distance between the probe and
the flow meter to 1,000 feet.
5.10.6 Calibrating the D.O.
Probe with a Flow
Meter
Prepare the probe as described above if this has not already been
done (fill the probe cavity with electrolyte and seat the mem-
brane).
Table 5-4 D.O. Probe SpecificationsCathode Gold
Anode Silver
Membrane FEP Teflon; 2 mil standard
Electrolyte Half-saturated KCl (Potassium Chloride)
Temp. Range 0° to +45° C
Polarizing Voltage 0.8 Volts (Nominal)
Probe Current in Air at 30° C 19 microamps (nominal)
Probe Current in Nitrogen at 30° C 0.15 microamps or less
Connection 12 ft. (3.2 m) cable with 5-pin male M/S connec-
tor
Response Time Typical response for dissolved oxygen, using
supplied membranes, is 90% in 20 seconds.
Response at low dissolved oxygen levels is typ-
ically 90% in 60 seconds.