Xylem Expert 800-900 - Manual (Page 19)

Manual
GB Manual Expert Log 800-900.doc
19
Actual value
If the Online function is activated by clicking Online, this field displays the current value of the
selected channel. Updating takes place every second. In online mode, the recording status and
memory status (in the status bar) as well as the battery capacity display are updated. It is likewise
possible to display the current height to the desired length specification, taking into account the water
level configuration settings.
Device type
The type of connected Data Logger is indicated under Device type:
- sealed gauge, air pressure compensated in each case (Expert Log 900)
- absolute (Expert Log 800), air pressure must be compensated separately (see Air
pressure- Compensation-module)
Conversion to
Recorded hydrostatic pressures can be converted into length values as per the water level
configuration settings. This conversion is carried out by means of the module Waterlevel-Converter.
Height of water above water level sensor (e):
- Linear measure (e) from the water level sensor to the
water surface. The height (e) is directly determined
from the hydrostatic pressure, the density of the
medium and acceleration due to gravity.
Depth to water (f):
- f = B - e = C + D -e
Height of water above sea level (g):
- g = A - f = A - (B - e) = A - (C + D - e)
Starting conditions at installation
Height of wellhead above sea level (A):
- During conversion to "Height of water above Sea
Level (g)", the height of the wellhead above sea level
must also be specified. Any other desired reference
point may also be used.
If the sea level, or the reference point selected
instead, is located above the well head, the value
must be entered with a negative sign.
Installation Depth (B):
- This value must be determined at sensor installation. It should correspond to the length from
the upper edge of the wellhead to the sensor-membrane. The membrane is identified by a
mark on the sensor.
Depth to water. (C):
- If this start condition is selected, the sensor measures the water height above the sensor (D)
at the start of the recording Write Configuration and uses the value entered here to
determine the installation depth of the water level sensor. (B).