Hanna Instruments HI 9914 - Manual (Page 16)

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CONDUCTIVITY PROBE MAINTENANCE
Preparation
Make sure that the protective sleeve is on the probe shaft and is intact.
Storage
Conductivity probes should be stored dry. If they are not to be used for a
while, clean and dry them thoroughly before storing them in a dry place.
Periodic maintenance
Inspect the probe and the cable. The cable used for the connection to the
controller must be intact. There must be no points of broken insulation on
the cable or cracks on the probe sleeve. If any cracks are present, replace
the probe and cable.
The connector must be clean and dry.
Cleaning procedure
Soak the probe in HI 7061 General Cleaning Solution for 1 hour.
If the probe has been left in highly concentrated fertilizer solution and
does not seem to have become clean, repeat the cleaning procedure. The
pins can also be cleaned with a cloth. The cloth has to be made of a soft
and nonabrasive material and does not scratch the pins.
Note: After performing a the cleaning procedure, rinse the probe thor-
oughly with distilled or tap water. Dry the probe and recalibrate
the controller.
Troubleshooting
• If the controller does not respond properly or constantly reads zero or
a value close to it:
- Check the probe and cable for cracks and replace it if needed.
• If the controller display shows 1. :
- The cable may be shorted or the probe broken. Replace it if needed.
• If the response seems sluggish:
- Follow the above cleaning procedure.
• If there are anomalies such as fluctuating numbers:
- Ensure that the probe has been properly mounted and constantly lies
in a well filled with solution.
Troubleshooting
Evaluate the electrode performance based on the following:
• Noise (readings fluctuate up and down) could be due to clogged/dirty
junction:
- Dry Membrane/Junction: soak in HI 70300 Storage Solution overnight.
Check that the installation has been done to create a well to maintain
the electrode bulb constantly moist.
• Low Slope:
- Check the electrode for cracks in the glass stem or bulb (replace the
electrode if cracks are found).
- Make sure that cable and connections are neither damaged nor lying
in a pool of water or solution.
• Slow Response/Excessive Drift:
- Soak the tip in HI 7061 Solution for 30 minutes, rinse thoroughly with
distilled water and then recalibrate the meter.
Note: It is always recommended to keep at least one spare electrode
handy. When anomalies are not resolved with a simple mainte-
nance, change the electrode (and recalibrate the controller) to see
if the problem is solved.