10
4.2 Correction for Settlement or Heave of the Reservoir Terminal
Periodic level surveys should be made of the elevation of the concrete pad on which the reservoir
terminal is located. Any measured settlement of the reservoir should be subtracted from the
calculated sensor elevations.
4.3 Corrections for Temperature
Temperature effects on liquid volume (liquid density) and on the expansion and contraction of
the liquid confines can be quite complex and in some ways self-canceling. Liquid lines in fills
are generally well insulated so that temperature effects tend to be insignificant. Systems exposed
to the atmosphere and to sunlight may suffer from rapidly changing temperatures at different
parts of the system causing significant fluctuation of the readings. In such cases, precautions may
be necessary to obtain readings at times of maximum temperature stability.
Temperature effects on the sensor can be corrected for but are usually quite insignificant
especially if the sensor is buried.
The elevation (E
T
) corrected for temperature is given by:
E
T
= E
0
– [(R
1
– R
0
) G + (T
1
– T
0
) K] +
∆
E
RES
Equation 2 - Elevation, corrected for temperature
Where;
T
0
is the initial temperature.
T
1
is the current temperature.
K is the temperature correction factor included on the calibration report.
Please note:
The calibration report shown in Figure 6 was developed using a simple manometer
and is good only over a range of three meters (ten feet) height differential between reservoir and
sensor. If this range is exceeded by the initial setup, or by large amounts of settlement, then there
are two options:
1) Continue to use the calibration report shown in Figure 6.
2) Use the second calibration report, supplied with the equipment, which was developed by
calibrating the pressure sensor over a wider range
.
