KROHNE SMARTSENS PH 8320 EN - Manual (Page 22)

4
OPERATION
22
SMARTSENS PH 8320
www.krohne.com 11/2013 - 4002543902 - MA SMARTSENS PH 8320 R02 en
4.2 Troubleshooting
Problem Possible cause Remedy
The pH sensor
does not deliver a
signal.
Mechanical damage of the
glass, e.g. small cracks.
This will shortcut the ion
exchange and deliver a pH
7 reading.
Exchange sensor.
Open circuit Check the cable wiring of the sensor cable on the junction box.
Otherwise connect the sensor to the primary master e.g.
PACTware
TM FTD/DTM or to the HART ® handheld to exclude a sensor
damage.
The pH sensor
delivers an
unstable signal.
The diaphragm in the
reference half cell does
not provide good contact
to the process medium
due to drying up or
coatings.
• Clean the diaphragm with hot soap or acid using a soft tissue
(details on page 24).
• Submerge sensor in water and increase the temperature to
+50...+60°C / +122...+140°F.
• Submerge sensor in 3 molar KCl solution at ambient temperature.
The decrease in temperature will cause the reference half cell to
suck in KCl solution through the diaphragm and regenerate the
diaphragms functionality.
High pH value Air bubble in the sensor
tip (no inner buffer
solution)
Protect the sensor tip with a protection cap as descriped on page 12.
Hold the sensor into a vertical position and help by rapid movements
of the wrist to shake the liquid down. Remove the protection cap and
check if there is still an air bubble inside the sensor tip. If necessary,
repeat this procedure one more time.
.book Page 22 Monday, November 18, 2013 10:42 AM