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11. TROUBLE SHOOTING
Faulty readings may show up as unstable, fluctuating readings, sudden large changes of readings
or readings of 9999 on dataloggers, unrelated to physical phenomena. The first task should be to
see if the fault lies with the readout device. If a datalogger is in use, try reading the sensors with
a portable GK-403, GK-404, or GK-405 Readout box.
11.1 Unstable Readings
Unstable readings with dataloggers may be caused by electrical noise from nearby power lines or
electrical equipment. Remove such equipment, if possible, or read the sensors when the power is
switched off.
Fluctuating readings may also be the result of air bubbles in the liquid lines or of plugged vent
lines. Follow the procedures outlined in Section 6 and Section 7.
11.2 Reading of 9999
These will show up on dataloggers if the reading is overrange. This can happen if the electrical
leads are shorted or open. Check the resistance between the black and red conductors. The
resistance should be 180 ohms
±
10 ohms plus five ohms for every 100 meters (328 feet) of lead
wire. If the resistance is substantially different from these values check for loose connections in
the terminal box and for visible signs of cable damage.
11.3 Sudden or Large Changes in Readings
Large or sudden changes in readings may be caused by leakage of liquid from the liquid lines.
Check the reservoir sight tube. If leakage is detected and there are more than one sensor
connected to the reservoir turn off each sensor valve at the base of the reservoir one by one until
the leaking sensor is found. If preferred this sensor can be left isolated from the system so that it
will not to disrupt the others.
