ATI
Q46C2 2Electode Conductivity System
Part 10
– System Maintenance
54
O&M Manual
Rev-H (6/19)
10.4 Cleaning the Sensor
Keep the sensor as clean as possible for optimum measurement accuracy. Frequency of cleaning
depends upon the process solution. Note that residue from calibration or cleaning solutions, and
even skin contact, can leave trace elements on the sensor that may affect the conductivity
measurement. This is especially true for extremely low conductivity applications. Whenever
cleaning or calibration is performed, make sure that all potential contaminants are removed from
the sensor before replacing it into the process.
NOTE:
Mechanical cleaning of the electrode surfaces may harm measurement quality. Do NOT
use wire brushes, sandpaper or the like to clean any conductivity electrode.
Wipe the inner electrode rod and the outer electrode tube (both inner and outer surfaces) with a
clean soft cloth or soft bristle brush. Then wash with warm soapy water. Rinse with tap water to
completely remove soap, then final rinse with distilled or de-ionized water.
If necessary, soak the sensor for several minutes in the mild soap solution. Soak for a few minutes,
then rinse the sensor thoroughly with clean tap water, and then rinse again with distilled or de-
ionized water.
NOTE
: De-ionized water will not remove soap.
After cleaning the sensor, check measurement and re-calibrate the sensor if necessary.
10.5 Sensor Testing
The first step in resolving any measurement problem is to determine whether the trouble lies in the
sensor or the transmitter. Since measurement problems can often be traced to foulants coating
the electrodes, cleaning the sensor using the method outlined in Section 10.4 should always be the
first step in any troubleshooting.
If the sensor cannot be calibrated after cleaning, perform the following test. A multimeter will be
needed.
1. Disconnect the sensor from the transmitter or junction box.
2. Using a multimeter, measure the resistance across the red and black wires of the sensor cable.
It should appear open (no shor
ts). If a short exists, then cut off 6” from the end of the sensor
cable. Strip the sensor wires and perform the test again. If a short still exists, contact factory.
3. Using a multimeter, verify continuity from the red wire to the outer (tube) electrode). Then verify
continuity from the black wire to the inner (rod) electrode. If continuity does not exist, contact
factory.
4.
Verify that the sensor’s temperature element (Pt1000 RTD) is functioning properly by
measuring the resistance between the sensor’s blue and white
wires. The nominal resistance
value at 25 ºC is 1097 ohms. Use the following table as a guide to the approximate resistance
value:
