Operating Instructions

27Operating Instructions VisiFerm
™
mA Sensors
TROUBLESHOOTINGMAINTENANCE
Figure 15: Effect of a product calibration (CP6) on an existing standard calibration
function based on the Zero Point Calibration (CP 1) and the Air Calibration (CIP 2).
NOTE: The product calibration is possible for DO values
in the range of 2 to 55 %-vol (20 – 550 mbar pO2).
A product calibration is performed as follows:
1) Connect one of the VisiFerm mA sensor with the power supply,
e.g. Sensor Power Cable M12 Ref 355288 (see figure 6) and
install a Wireless Converter BT Ref 242333
2) Select the desired sensor from the sensor list
3) Go to «Process Settings»
4) Click «Start» to start the product calibration wizard
5) Follow the instruction on the screen
NOTE: Alternatively, the product calibration may be
performed with a field device on side the measuring point.
7. 5 Cleaning
This chapter outlines a manual cleaning procedure for the care
and maintenance of optical dissolved oxygen (ODO) sensors
including a procedure for the cleaning the sensing membrane in
particular.
Cleaning the Sensor
Carry out the cleaning procedure as follows:
1) Remove sensor from the measuring setup
2) Check if the ODO Cap is mounted firmly on the shaft
3) Soak a dust-free cloth or tissue paper with water and wipe the
wetted parts with it. Thoroughly rinse the wetted parts and
the sensing membrane with deionised water afterwards
4) Dry the wetted parts with a clean dust-free cloth or tissue
and store the sensor in dry and dark conditions (ODO Caps
are light-sensitive)
5) If the sensing-membrane on the front of the cap is
contaminated with oil, grease or other organic matter, soak
a clean dust-free cloth with isopropyl alcohol. Rinse residual
isopropyl alcohol immediately from the membrane with
deionised water and gently wipe over the membrane
6) After cleaning always perform a new calibration before
carrying out measurements. (See chapter 7.3 in the
corresponding Operating Instruction Manual)
ATTENTION: Cleaning, assembly and maintenance
should be performed by personnel trained in such
work. Do not use any abrasive tissues or cleaning
materials and do not use any cleaning chemicals other
than described above. Before removing the sensor
from the measuring setup, always make sure that the
setup is pressure-less, cold and that no process me-
dium can be accidentally spilled. When removing and
cleaning the sensor, it is recommended to wear safety
glasses and protective gloves.
8 Troubleshooting
8.1 Sensor Self-Diagnostic
VisiFerm mA sensors provide a self-diagnostic functionality to
detect and identify the most common sensor malfunctions. Both
interfaces, analog 4-20 mA or digital HART, may provide warning
and error messages. The analog 4–20 mA interface can be con-
figured according to the NAMUR recommendations to indicate
an abnormal event (See chapter 5.2.3). Use ArcAir for monitoring
the sensor status and for troubleshooting. The following types of
messages are provided by the self-diagnosis function.
8.1.1 Warnings
Warning Cause / Solution
DO reading below The oxygen reading is too low
lower limit (DO < 0%-sat). Make a new zero-point
calibration (Chapter 7.3.3)
DO reading above The oxygen reading is too high
upper limit (DO > 300 %-sat). Make a new calibration
in oxygen saturated medium. (See
chapter 7.3.2). If not successful, replace
the sensor cap
DO reading unstable If continuously happening, use a new
cap or check the process regulation.
If the problem still appears, call our
Technical Support
T reading below The temperature is below the user defined
lower limit measurement temperature range. If the
process temperature is outside this range,
the sensor will not perform DO readings
T reading above The temperature is above the user
upper limit defined measurement temperature range.
If the process temperature is outside this
range, the sensor will not perform DO
readings