11
Trouble Shooting
Erratic Readings
Erratic readings can be caused by a damaged transmitter, damaged cable, poor connec-
tions or improper operation of readout equipment. In most cases, erratic readings are
due to moisture getting into the system. Assuming that the readout equipment is
working correctly, the first thing to check is the connection. Look for moisture between
contacts or a loose or broken wire. If the connection appears OK, pull the transmitter
up a known distance while monitoring its output. If the transmitter responds approxi-
mately as it should, but the reading is still erratic, most likely the cable is damaged. If
the transmitter does not respond approximately as it should, it is most likely that the
sensor is damaged. In either case, consult the factory.
Erratic and erroneous readings can also occur due to improper grounding. See Ground-
ing Issues, next page.
Oscillating Readings Over Time
If, after time, your transmitter is functioning normally but your data is showing a cyclic
effect in the absence of water level changes, you are probably seeing barometric
changes. The amount is usually .5 to 1.5 feet of water. This can be caused by a
plugged vent tube in the cable or actual water level changes in the aquifer itself in
response to barometric pressure changes. This effect can occur in tight formations
where the transmitter will immediately pick up barometric changes but the aquifer will
not. If you think you are having this type of problem you will have to record the
barometric pressure as well as the water level pressure and compensate the data. If it
appears that the vent tube is plugged, consult the factory.
If a desiccant tube is not installed in line with the cable, water may have condensed in
your vent tube causing it to plug. After you are finished installing the desiccant tube
you can test the vent tube by applying a small amount of pressure to the end of the
desiccant tube and seeing if this affects the transmitter reading.
Zero Readings When Pressurized
Continuous zero readings are caused by an open circuit which usually indicates broken
cable, a bad connection, or possibly a damaged transmitter. Check the connector to see
if a wire has become loose, or if the cable has been cut. If neither of these appears to
cause the problem, the transmitter needs factory repair.
