Evoqua Wallace & Tiernan Depolox 3 plus, Manual

Page: 126 / 157

WT.050.560.001.UA.IM.0714 111
Depolox
®
3 plus ReSIDUAl ANAlYZeR
eVoQUA W3T140188
4.4.2 Maintenance of the Membrane Probes
NOTE: Do not touch the membrane or reference electrode.
Before unscrewing the membrane cap, remove the elastomer seal to allow air
into the vent hole. Unscrew the membrane cap, clean the reference electrode
with distilled water and then dry with a clean paper towel. Cover the vent hole
with the elastomer seal. Refill the cap with new electrolyte (refer to paragraph
2.3, Membrane Sensor). If the signal is still low or unstable, it may be neces-
sary to replace the cap with a new one (refer to Section 6 - Spare Parts List).
After this procedure, the probe requires a run-in time of about one to two
hours before recalibration.
4.4.3 Troubleshooting
The following troubleshooting table is provided for determining and correcting
most common troubles.
Table 4.4 - Troubleshooting - Membrane Sensor Kit
FAULT CONDITION POSSIBLE CAUSE CORRECTIVE ACTION
Insufficient flow of measuring
water free runoff prevented; back
pressure too high check for free drain or return
dirt in cell clean measuring cell
air bubbles check sample water take-off
screen in water inlet blocked clean
inlet valve closed open valve
Air bubbles leaking O-rings replace O-rings
incorrect fittings check and if necessary tighten or
replace
DIS Electrode current too low electrolyte exhausted perform sensor maintenance
membrane defective replace membrane cap
DIS Span cannot be adjusted
measuring cell gives insufficient
current perform sensor maintenance
The minimum current difference
between un-chlorinated and
chlorinated water with 1 mg/l
residual DIS must be at least >2µA.
If the difference is smaller, carry out
maintenance.
Strong fluctuations in display,
though chlorine concentration
is constant sample water flow too low check; if necessary, clean inlet
electrolyte exhausted perform sensor maintenance