Precision Water Level Instrument
Unidata Manual 6293 - Precision Water Level Instruments Issue 2.1
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cable, turn the pulley to engage the index beads into the holes in the float
pulley groove.
5.3 Setting the Instrument Water Level
To do this:
1. Remove the front cover of the instrument.
2. Set the battery switch (number 8) to the ON position.
3. Use the buttons to set the LCD display to read the approximate water level
value.
4. Turn the float pulley to simulate an increase in water level. Confirm that the
LCD increases. If it changes in the wrong direction change the position of
switches 1 and 2.
5. Rock the pulley a little to disturb the water surface. The display should move
up and down and settle on the same level (±1mm) each time. If it doesn’t, the
float system is not moving freely. The float, line or counterweight may be
rubbing on an obstruction or the instrument pulley may have on its shaft.
6. Use the buttons to adjust the display to the exact value.
The water level that you set should be referred to a site datum. This datum
should originate from a fixed point that will not change during the period of the
measuring project.
The value displayed should be set high enough so that changes in the water level
do not cause it to fall below zero. If the pulley shaft is rotated back past the zero
(00000) reading, the display and the data logger will “wrap around” to 65535.
For instance, if you are measuring a bore with water level 20 metres down; set
the display to 20 metres (20000). When the water level rises, the reading will
change to 19999. When the water level falls, the reading will change to 20001.
