10
MW190
Bench Meter
6. OPERATIONAL GUIDE
Plug the 12 VDC adapter into the power supply socket.
Connect the DO probe to the 7-pin connector. Make sure the probe sleeve is properly
inserted and tighten the threaded ring.
Turn the instrument on by pressing ON/OFF. All LCD tags are displayed and a beep is
heard while the instrument performs a self test.
y
After a few seconds “Cond” message appears on the LCD to inform the user that the
probe is in auto-conditioning (automatic polarization) mode.
y
When this message disappears, the probe is polarized and the instrument can be
calibrated.
y
If the probe is disconnected, the meter will display “----”.
PROBE POLARIZATION
The probe is under polarization with a fixed voltage of approximately 800 mV.
Probe polarization is essential for stable measurements with the same recurring degree
of accuracy.
With the probe properly polarized, oxygen is continually consumed when it passes
through the sensitive diaphragm and dissolves in the electrolyte solution contained in
the probe.
If polarization is interrupted, the electrolyte solution continues to be enriched with oxygen
until it reaches an equilibrium with the surrounding solution.
