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Installation
3.4 Offset correction for non horizontal installations
Transducer
5cm
m
Middle of cup
by storing the installation angle directly inside the installed T8
through the tensioLINK interface.
The middle of the cup is regarded to be the measuring level. The
correction is largest for a vertical water column (at 0
the cosine of the installation angle, as shown on the table below. In
an absolutely horizontal position the offset is zero.
Example: A 5 cm vertical column of water below the pressure
sensor will create an 0.5 kPa offset. This means that when the soil
water tension is 0 kPa the sensor will indicate -0.5 kPa.
Table showing the offset correction when a 5 cm column of water is
tilted at various angles:
Angle to vertical line
Offset correction in [kPa]
Angle to vertical line
Offset correction in [kPa]
The offset is entered as + in your logger if you regard the soil water
tension to be negative (0 ... -85 kPa).
The pressure transducer is calibrated without
a cup. Thus, no compensation is required for
horizontal installations.
If a T8 is installed in a non horizontal
position, the vertical water column draws on
the pressure sensor and causes an offset
shift.
Compensate the offset:
by calculation,
by entering the installation angle in the
Infield7 for spot readings,
in the configuration of a data logger by
setting an offset,
0°
10°
+0,5
+0,49
45°
60°
+0,35
+0,25
22/58
o
) and varies as
15°
20°
+0,48
+0,47
70°
75°
+0,17
+0,13
25°
30°
+0,45
+0,43
80°
90°
+0,09
0
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