Geosense VWLSS-200, Руководство по установке

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17
V1.7 January 2021
Geosense Calibration Sheets provide a NEGATIVE (
-
)
Calibration Factor value for Settlement Cells. The equations
REQUIRE a POSITIVE (+) Calibration Factor to produce a
NEGATIVE value representing Settlement.
5.2.2 Calculation of data for a self compensating, ‘ vented ’ system.
Settlement = {(CF * ∆ R) + (T
k
* ∆ T)} / SG
Δ R = R
c
– R
0
Δ T = T
c
– T
0
Where:
CF = Calibration Factor (from Calibration Sheet)
SG = Specific gravity of system liquid (1.037 kg/l)
R
0
= Initial site reading
R
C
= Current reading
T
K
= Thermal Factor (from Calibration Sheet)
T
0
= Initial Temperature
T
C
= Current Temperature
For example, using the non
-
vented equation:
Initial VW Readings R
0
after installation was 7905 Digits (Hz
2
/1000)
at sensor temperature T
0
of 17 °C
and Barometric pressure B
0
of 1012 mb
Current VW Reading R
C
is 7530 Digits
at sensor temperature T
C
of 15 °C
and Barometric pressure of 1025 mb
Calibration sheet shows
-
0.002324 m/Digit for CF
and
-
0.010512 m/(°C) for T
K
Δ R = R
C
– R
0
= 7530
-
7905 =
-
375 Digits
Δ T = T
C
– T
0
= 15
-
17 =
-
2
0
C
Δ B = B
C
– B
0
= 1012
-
1025 =
-
13 mb
Settlement = [{(0.002324 *
-
375) + (
-
0.010512 *
-
2)}
-
(0.0102 *
-
13)] / 1.037
= [{
-
0.8715 + 0.021 } + 0.1326 ] / 1.037
= 0.692 m
From the above sample calculation, it can be seen that generally the temperature effects
are small, which is commonly true for buried sensors. However, the effects upon the
liquid cannot be included in this compensation and where tubing is exposed the effects
can be more significant.
** If calculated settlements appear to be RISING, check the liquid level in the reservoir
and check the elevation of the reservoir in case it has settled. Also confirm that a positive
Calibration Factor has been used in the calculations.